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2018-08-20Merge tag 'trace-v4.19' of ↵Linus Torvalds1-30/+5
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: - Restructure of lockdep and latency tracers This is the biggest change. Joel Fernandes restructured the hooks from irqs and preemption disabling and enabling. He got rid of a lot of the preprocessor #ifdef mess that they caused. He turned both lockdep and the latency tracers to use trace events inserted in the preempt/irqs disabling paths. But unfortunately, these started to cause issues in corner cases. Thus, parts of the code was reverted back to where lockdep and the latency tracers just get called directly (without using the trace events). But because the original change cleaned up the code very nicely we kept that, as well as the trace events for preempt and irqs disabling, but they are limited to not being called in NMIs. - Have trace events use SRCU for "rcu idle" calls. This was required for the preempt/irqs off trace events. But it also had to not allow them to be called in NMI context. Waiting till Paul makes an NMI safe SRCU API. - New notrace SRCU API to allow trace events to use SRCU. - Addition of mcount-nop option support - SPDX headers replacing GPL templates. - Various other fixes and clean ups. - Some fixes are marked for stable, but were not fully tested before the merge window opened. * tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits) tracing: Fix SPDX format headers to use C++ style comments tracing: Add SPDX License format tags to tracing files tracing: Add SPDX License format to bpf_trace.c blktrace: Add SPDX License format header s390/ftrace: Add -mfentry and -mnop-mcount support tracing: Add -mcount-nop option support tracing: Avoid calling cc-option -mrecord-mcount for every Makefile tracing: Handle CC_FLAGS_FTRACE more accurately Uprobe: Additional argument arch_uprobe to uprobe_write_opcode() Uprobes: Simplify uprobe_register() body tracepoints: Free early tracepoints after RCU is initialized uprobes: Use synchronize_rcu() not synchronize_sched() tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister() ftrace: Remove unused pointer ftrace_swapper_pid tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage" tracing/irqsoff: Handle preempt_count for different configs tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage" tracing: irqsoff: Account for additional preempt_disable trace: Use rcu_dereference_raw for hooks from trace-event subsystem tracing/kprobes: Fix within_notrace_func() to check only notrace functions ...
2018-08-15Merge tag 'drm-next-2018-08-15' of git://anongit.freedesktop.org/drm/drmLinus Torvalds3-85/+264
Pull drm updates from Dave Airlie: "This is the main drm pull request for 4.19. Rob has some new hardware support for new qualcomm hw that I'll send along separately. This has the display part of it, the remaining pull is for the acceleration engine. This also contains a wound-wait/wait-die mutex rework, Peter has acked it for merging via my tree. Otherwise mostly the usual level of activity. Summary: core: - Wound-wait/wait-die mutex rework - Add writeback connector type - Add "content type" property for HDMI - Move GEM bo to drm_framebuffer - Initial gpu scheduler documentation - GPU scheduler fixes for dying processes - Console deferred fbcon takeover support - Displayport support for CEC tunneling over AUX panel: - otm8009a panel driver fixes - Innolux TV123WAM and G070Y2-L01 panel driver - Ilitek ILI9881c panel driver - Rocktech RK070ER9427 LCD - EDT ETM0700G0EDH6 and EDT ETM0700G0BDH6 - DLC DLC0700YZG-1 - BOE HV070WSA-100 - newhaven, nhd-4.3-480272ef-atxl LCD - DataImage SCF0700C48GGU18 - Sharp LQ035Q7DB03 - p079zca: Refactor to support multiple panels tinydrm: - ILI9341 display panel New driver: - vkms - virtual kms driver to testing. i915: - Icelake: Display enablement DSI support IRQ support Powerwell support - GPU reset fixes and improvements - Full ppgtt support refactoring - PSR fixes and improvements - Execlist improvments - GuC related fixes amdgpu: - Initial amdgpu documentation - JPEG engine support on VCN - CIK uses powerplay by default - Move to using core PCIE functionality for gens/lanes - DC/Powerplay interface rework - Stutter mode support for RV - Vega12 Powerplay updates - GFXOFF fixes - GPUVM fault debugging - Vega12 GFXOFF - DC improvements - DC i2c/aux changes - UVD 7.2 fixes - Powerplay fixes for Polaris12, CZ/ST - command submission bo_list fixes amdkfd: - Raven support - Power management fixes udl: - Cleanups and fixes nouveau: - misc fixes and cleanups. msm: - DPU1 support display controller in sdm845 - GPU coredump support. vmwgfx: - Atomic modesetting validation fixes - Support for multisample surfaces armada: - Atomic modesetting support completed. exynos: - IPPv2 fixes - Move g2d to component framework - Suspend/resume support cleanups - Driver cleanups imx: - CSI configuration improvements - Driver cleanups - Use atomic suspend/resume helpers - ipu-v3 V4L2 XRGB32/XBGR32 support pl111: - Add Nomadik LCDC variant v3d: - GPU scheduler jobs management sun4i: - R40 display engine support - TCON TOP driver mediatek: - MT2712 SoC support rockchip: - vop fixes omapdrm: - Workaround for DRA7 errata i932 - Fix mm_list locking mali-dp: - Writeback implementation PM improvements - Internal error reporting debugfs tilcdc: - Single fix for deferred probing hdlcd: - Teardown fixes tda998x: - Converted to a bridge driver. etnaviv: - Misc fixes" * tag 'drm-next-2018-08-15' of git://anongit.freedesktop.org/drm/drm: (1506 commits) drm/amdgpu/sriov: give 8s for recover vram under RUNTIME drm/scheduler: fix param documentation drm/i2c: tda998x: correct PLL divider calculation drm/i2c: tda998x: get rid of private fill_modes function drm/i2c: tda998x: move mode_valid() to bridge drm/i2c: tda998x: register bridge outside of component helper drm/i2c: tda998x: cleanup from previous changes drm/i2c: tda998x: allocate tda998x_priv inside tda998x_create() drm/i2c: tda998x: convert to bridge driver drm/scheduler: fix timeout worker setup for out of order job completions drm/amd/display: display connected to dp-1 does not light up drm/amd/display: update clk for various HDMI color depths drm/amd/display: program display clock on cache match drm/amd/display: Add NULL check for enabling dp ss drm/amd/display: add vbios table check for enabling dp ss drm/amd/display: Don't share clk source between DP and HDMI drm/amd/display: Fix DP HBR2 Eye Diagram Pattern on Carrizo drm/amd/display: Use calculated disp_clk_khz value for dce110 drm/amd/display: Implement custom degamma lut on dcn drm/amd/display: Destroy aux_engines only once ...
2018-08-13Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds1-1/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Thomas Gleixner: "A large update to RCU: Preparatory work for consolidating the RCU flavors: - Introduce grace-period sequence numbers to the RCU-bh, RCU-preempt, and RCU-sched flavors, replacing the old ->gpnum and ->completed pair of fields. This change allows lockless code to obtain the complete grace-period state with a single READ_ONCE(), which is needed to maintain tolerable lock contention during the upcoming consolidation of the three RCU flavors. Note that grace-period sequence numbers are already used by rcu_barrier(), expedited RCU grace periods, and SRCU, and are thus already heavily used and well-tested. Joel Fernandes contributed a number of excellent fixes and improvements. - Clean up some grace-period-reporting loose ends, including improving the handling of quiescent states from offline CPUs and fixing some false-positive WARN_ON_ONCE() invocations. (Strictly speaking, the WARN_ON_ONCE() invocations were quite correct, but their invariants were (harmlessly) violated by the earlier sloppy handling of quiescent states from offline CPUs.) In addition, improve grace-period forward-progress guarantees so as to allow removal of fail-safe checks that required otherwise needless lock acquisitions. Finally, add more diagnostics to help debug the upcoming consolidation of the RCU-bh, RCU-preempt, and RCU-sched flavors. The rest: - SRCU updates - Updates to rcutorture and associated scripting. - The usual pile of miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (118 commits) rcutorture: Fix rcu_barrier successes counter rcutorture: Add support to detect if boost kthread prio is too low rcutorture: Use monotonic timestamp for stall detection rcutorture: Make boost test more robust rcutorture: Disable RT throttling for boost tests rcutorture: Emphasize testing of single reader protection type rcutorture: Handle extended read-side critical sections rcutorture: Make rcu_torture_timer() use rcu_torture_one_read() rcutorture: Use per-CPU random state for rcu_torture_timer() rcutorture: Use atomic increment for n_rcu_torture_timers rcutorture: Extract common code from rcu_torture_reader() rcuperf: Remove unused torturing_tasks() function rcu: Remove rcutorture test version and sequence number rcutorture: Change units of onoff_interval to jiffies rcu: Assign higher prio to RCU threads if rcutorture is built-in rculist: Improve documentation for list_for_each_entry_from_rcu() srcu: Add grace-period number to rcutorture statistics printout rcu: Print stall-warning NMI dyntick state in hexadecimal MAINTAINERS: Update RCU, SRCU, and TORTURE-TEST entries rcu: Make rcu_seq_diff() more exact ...
2018-08-10tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and ↵Steven Rostedt (VMware)1-12/+2
unify their usage" Joel Fernandes created a nice patch that cleaned up the duplicate hooks used by lockdep and irqsoff latency tracer. It made both use tracepoints. But it caused lockdep to trigger several false positives. We have not figured out why yet, but removing lockdep from using the trace event hooks and just call its helper functions directly (like it use to), makes the problem go away. This is a partial revert of the clean up patch c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage") that adds direct calls for lockdep, but also keeps most of the clean up done to get rid of the horrible preprocessor if statements. Link: http://lkml.kernel.org/r/20180806155058.5ee875f4@gandalf.local.home Cc: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Fixes: c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-07-31tracing: Centralize preemptirq tracepoints and unify their usageJoel Fernandes (Google)1-21/+14
This patch detaches the preemptirq tracepoints from the tracers and keeps it separate. Advantages: * Lockdep and irqsoff event can now run in parallel since they no longer have their own calls. * This unifies the usecase of adding hooks to an irqsoff and irqson event, and a preemptoff and preempton event. 3 users of the events exist: - Lockdep - irqsoff and preemptoff tracers - irqs and preempt trace events The unification cleans up several ifdefs and makes the code in preempt tracer and irqsoff tracers simpler. It gets rid of all the horrific ifdeferry around PROVE_LOCKING and makes configuration of the different users of the tracepoints more easy and understandable. It also gets rid of the time_* function calls from the lockdep hooks used to call into the preemptirq tracer which is not needed anymore. The negative delta in lines of code in this patch is quite large too. In the patch we introduce a new CONFIG option PREEMPTIRQ_TRACEPOINTS as a single point for registering probes onto the tracepoints. With this, the web of config options for preempt/irq toggle tracepoints and its users becomes: PREEMPT_TRACER PREEMPTIRQ_EVENTS IRQSOFF_TRACER PROVE_LOCKING | | \ | | \ (selects) / \ \ (selects) / TRACE_PREEMPT_TOGGLE ----> TRACE_IRQFLAGS \ / \ (depends on) / PREEMPTIRQ_TRACEPOINTS Other than the performance tests mentioned in the previous patch, I also ran the locking API test suite. I verified that all tests cases are passing. I also injected issues by not registering lockdep probes onto the tracepoints and I see failures to confirm that the probes are indeed working. This series + lockdep probes not registered (just to inject errors): [ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok | [ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok | [ 0.000000] sirq-safe-A => hirqs-on/12:FAILED|FAILED| ok | [ 0.000000] sirq-safe-A => hirqs-on/21:FAILED|FAILED| ok | [ 0.000000] hard-safe-A + irqs-on/12:FAILED|FAILED| ok | [ 0.000000] soft-safe-A + irqs-on/12:FAILED|FAILED| ok | [ 0.000000] hard-safe-A + irqs-on/21:FAILED|FAILED| ok | [ 0.000000] soft-safe-A + irqs-on/21:FAILED|FAILED| ok | [ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok | [ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok | With this series + lockdep probes registered, all locking tests pass: [ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok | [ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok | [ 0.000000] sirq-safe-A => hirqs-on/12: ok | ok | ok | [ 0.000000] sirq-safe-A => hirqs-on/21: ok | ok | ok | [ 0.000000] hard-safe-A + irqs-on/12: ok | ok | ok | [ 0.000000] soft-safe-A + irqs-on/12: ok | ok | ok | [ 0.000000] hard-safe-A + irqs-on/21: ok | ok | ok | [ 0.000000] soft-safe-A + irqs-on/21: ok | ok | ok | [ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok | [ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok | Link: http://lkml.kernel.org/r/20180730222423.196630-4-joel@joelfernandes.org Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-07-30lockdep: Use this_cpu_ptr instead of get_cpu_var statsJoel Fernandes (Google)1-9/+1
get_cpu_var disables preemption which has the potential to call into the preemption disable trace points causing some complications. There's also no need to disable preemption in uses of get_lock_stats anyway since preempt is already disabled. So lets simplify the code. Link: http://lkml.kernel.org/r/20180730222423.196630-2-joel@joelfernandes.org Suggested-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-07-25locking/rtmutex: Allow specifying a subclass for nested lockingPeter Rosin1-4/+25
Needed for annotating rt_mutex locks. Tested-by: John Sperbeck <jsperbeck@google.com> Signed-off-by: Peter Rosin <peda@axentia.se> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Deepa Dinamani <deepadinamani@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Chang <dpf@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: Wolfram Sang <wsa@the-dreams.de> Link: http://lkml.kernel.org/r/20180720083914.1950-2-peda@axentia.se Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-17Merge branch 'for-mingo' of ↵Ingo Molnar1-1/+4
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu Pull RCU updates from Paul E. McKenney: - An optimization and a fix for RCU expedited grace periods, with the fix being from Boqun Feng. - Miscellaneous fixes, including a lockdep-annotation fix from Boqun Feng. - SRCU updates. - Updates to rcutorture and associated scripting. - Introduce grace-period sequence numbers to the RCU-bh, RCU-preempt, and RCU-sched flavors, replacing the old ->gpnum and ->completed pair of fields. This change allows lockless code to obtain the complete grace-period state with a single READ_ONCE(), which is needed to maintain tolerable lock contention during the upcoming consolidation of the three RCU flavors. Note that grace-period sequence numbers are already used by rcu_barrier(), expedited RCU grace periods, and SRCU, and are thus already heavily used and well-tested. Joel Fernandes contributed a number of excellent fixes and improvements. - Clean up some grace-period-reporting loose ends, including improving the handling of quiescent states from offline CPUs and fixing some false-positive WARN_ON_ONCE() invocations. (Strictly speaking, the WARN_ON_ONCE() invocations were quite correct, but their invariants were (harmlessly) violated by the earlier sloppy handling of quiescent states from offline CPUs.) In addition, improve grace-period forward-progress guarantees so as to allow removal of fail-safe checks that required otherwise needless lock acquisitions. Finally, add more diagnostics to help debug the upcoming consolidation of the RCU-bh, RCU-preempt, and RCU-sched flavors. - Additional miscellaneous fixes, including those contributed by Byungchul Park, Mauro Carvalho Chehab, Joe Perches, Joel Fernandes, Steven Rostedt, Andrea Parri, and Neil Brown. - Additional torture-test changes, including several contributed by Arnd Bergmann and Joel Fernandes. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-06Merge branch 'vmwgfx-next' of git://people.freedesktop.org/~thomash/linux ↵Dave Airlie3-85/+264
into drm-next A patchset worked out together with Peter Zijlstra. Ingo is OK with taking it through the DRM tree: This is a small fallout from a work to allow batching WW mutex locks and unlocks. Our Wound-Wait mutexes actually don't use the Wound-Wait algorithm but the Wait-Die algorithm. One could perhaps rename those mutexes tree-wide to "Wait-Die mutexes" or "Deadlock Avoidance mutexes". Another approach suggested here is to implement also the "Wound-Wait" algorithm as a per-WW-class choice, as it has advantages in some cases. See for example http://www.mathcs.emory.edu/~cheung/Courses/554/Syllabus/8-recv+serial/deadlock-compare.html Now Wound-Wait is a preemptive algorithm, and the preemption is implemented using a lazy scheme: If a wounded transaction is about to go to sleep on a contended WW mutex, we return -EDEADLK. That is sufficient for deadlock prevention. Since with WW mutexes we also require the aborted transaction to sleep waiting to lock the WW mutex it was aborted on, this choice also provides a suitable WW mutex to sleep on. If we were to return -EDEADLK on the first WW mutex lock after the transaction was wounded whether the WW mutex was contended or not, the transaction might frequently be restarted without a wait, which is far from optimal. Note also that with the lazy preemption scheme, contrary to Wait-Die there will be no rollbacks on lock contention of locks held by a transaction that has completed its locking sequence. The modeset locks are then changed from Wait-Die to Wound-Wait since the typical locking pattern of those locks very well matches the criterion for a substantial reduction in the number of rollbacks. For reservation objects, the benefit is more unclear at this point and they remain using Wait-Die. Signed-off-by: Dave Airlie <airlied@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180703105339.4461-1-thellstrom@vmware.com
2018-07-03locking: Implement an algorithm choice for Wound-Wait mutexesThomas Hellstrom3-19/+150
The current Wound-Wait mutex algorithm is actually not Wound-Wait but Wait-Die. Implement also Wound-Wait as a per-ww-class choice. Wound-Wait is, contrary to Wait-Die a preemptive algorithm and is known to generate fewer backoffs. Testing reveals that this is true if the number of simultaneous contending transactions is small. As the number of simultaneous contending threads increases, Wait-Wound becomes inferior to Wait-Die in terms of elapsed time. Possibly due to the larger number of held locks of sleeping transactions. Update documentation and callers. Timings using git://people.freedesktop.org/~thomash/ww_mutex_test tag patch-18-06-15 Each thread runs 100000 batches of lock / unlock 800 ww mutexes randomly chosen out of 100000. Four core Intel x86_64: Algorithm #threads Rollbacks time Wound-Wait 4 ~100 ~17s. Wait-Die 4 ~150000 ~19s. Wound-Wait 16 ~360000 ~109s. Wait-Die 16 ~450000 ~82s. Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Gustavo Padovan <gustavo@padovan.org> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Sean Paul <seanpaul@chromium.org> Cc: David Airlie <airlied@linux.ie> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linux-doc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Co-authored-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-07-03locking: WW mutex cleanupPeter Ziljstra1-77/+125
Make the WW mutex code more readable by adding comments, splitting up functions and pointing out that we're actually using the Wait-Die algorithm. Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Gustavo Padovan <gustavo@padovan.org> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Sean Paul <seanpaul@chromium.org> Cc: David Airlie <airlied@linux.ie> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linux-doc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Co-authored-by: Thomas Hellstrom <thellstrom@vmware.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-06-25torture: Keep old-school dmesg formatPaul E. McKenney1-0/+3
This commit adds "#define pr_fmt(fmt) fmt" to the torture-test files in order to keep the current dmesg format. Once Joe's commits have hit mainline, these definitions will be changed in order to automatically generate the dmesg line prefix that the scripts expect. This will have the beneficial side-effect of allowing printk() formats to be used more widely and of shortening some pr_*() lines. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Joe Perches <joe@perches.com>
2018-06-25torture: Make online/offline messages appear only for verbose=2Paul E. McKenney1-1/+1
Some bugs reproduce quickly only at high CPU-hotplug rates, so the rcutorture TREE03 scenario now has only 200 milliseconds spacing between CPU-hotplug operations. At this rate, the torture-test pair of console messages per operation becomes a bit voluminous. This commit therefore converts the torture-test set of "verbose" kernel-boot arguments from bool to int, and prints the extra console messages only when verbose=2. The default is still verbose=1. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-06-24Merge branch 'locking-urgent-for-linus' of ↵Linus Torvalds2-6/+7
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Thomas Gleixner: "A set of fixes and updates for the locking code: - Prevent lockdep from updating irq state within its own code and thereby confusing itself. - Buid fix for older GCCs which mistreat anonymous unions - Add a missing lockdep annotation in down_read_non_onwer() which causes up_read_non_owner() to emit a lockdep splat - Remove the custom alpha dec_and_lock() implementation which is incorrect in terms of ordering and use the generic one. The remaining two commits are not strictly fixes. They provide irqsave variants of atomic_dec_and_lock() and refcount_dec_and_lock(). These are required to merge the relevant updates and cleanups into different maintainer trees for 4.19, so routing them into mainline without actual users is the sanest approach. They should have been in -rc1, but last weekend I took the liberty to just avoid computers in order to regain some mental sanity" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/qspinlock: Fix build for anonymous union in older GCC compilers locking/lockdep: Do not record IRQ state within lockdep code locking/rwsem: Fix up_read_non_owner() warning with DEBUG_RWSEMS locking/refcounts: Implement refcount_dec_and_lock_irqsave() atomic: Add irqsave variant of atomic_dec_and_lock() alpha: Remove custom dec_and_lock() implementation
2018-06-21locking/lockdep: Do not record IRQ state within lockdep codeSteven Rostedt (VMware)1-6/+6
While debugging where things were going wrong with mapping enabling/disabling interrupts with the lockdep state and actual real enabling and disabling interrupts, I had to silent the IRQ disabling/enabling in debug_check_no_locks_freed() because it was always showing up as it was called before the splat was. Use raw_local_irq_save/restore() for not only debug_check_no_locks_freed() but for all internal lockdep functions, as they hide useful information about where interrupts were used incorrectly last. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Link: https://lkml.kernel.org/lkml/20180404140630.3f4f4c7a@gandalf.local.home Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-20locking/rwsem: Fix up_read_non_owner() warning with DEBUG_RWSEMSWaiman Long1-0/+1
It was found that the use of up_read_non_owner() in NFS was causing the following warning when DEBUG_RWSEMS was configured. DEBUG_LOCKS_WARN_ON(sem->owner != ((struct task_struct *)(1UL << 0))) Looking into the rwsem.c file, it was discovered that the corresponding down_read_non_owner() function was not setting the owner field properly. This is fixed now, and the warning should be gone. Fixes: 5149cbac4235 ("locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Gavin Schenk <g.schenk@eckelmann.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: linux-nfs@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1527168398-4291-1-git-send-email-longman@redhat.com
2018-06-12treewide: kzalloc() -> kcalloc()Kees Cook1-2/+4
The kzalloc() function has a 2-factor argument form, kcalloc(). This patch replaces cases of: kzalloc(a * b, gfp) with: kcalloc(a * b, gfp) as well as handling cases of: kzalloc(a * b * c, gfp) with: kzalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kzalloc_array(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kzalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kzalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kzalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kzalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(u8) * COUNT + COUNT , ...) | kzalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kzalloc( - sizeof(char) * COUNT + COUNT , ...) | kzalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kzalloc + kcalloc ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kzalloc + kcalloc ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kzalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kzalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kzalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kzalloc(C1 * C2 * C3, ...) | kzalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kzalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kzalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kzalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kzalloc(sizeof(THING) * C2, ...) | kzalloc(sizeof(TYPE) * C2, ...) | kzalloc(C1 * C2 * C3, ...) | kzalloc(C1 * C2, ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kzalloc + kcalloc ( - (E1) * E2 + E1, E2 , ...) | - kzalloc + kcalloc ( - (E1) * (E2) + E1, E2 , ...) | - kzalloc + kcalloc ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12treewide: kmalloc() -> kmalloc_array()Kees Cook1-2/+6
The kmalloc() function has a 2-factor argument form, kmalloc_array(). This patch replaces cases of: kmalloc(a * b, gfp) with: kmalloc_array(a * b, gfp) as well as handling cases of: kmalloc(a * b * c, gfp) with: kmalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kmalloc_array(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kmalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The tools/ directory was manually excluded, since it has its own implementation of kmalloc(). The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kmalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kmalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kmalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(char) * COUNT + COUNT , ...) | kmalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kmalloc + kmalloc_array ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kmalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kmalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kmalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kmalloc(C1 * C2 * C3, ...) | kmalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kmalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kmalloc(sizeof(THING) * C2, ...) | kmalloc(sizeof(TYPE) * C2, ...) | kmalloc(C1 * C2 * C3, ...) | kmalloc(C1 * C2, ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - (E1) * E2 + E1, E2 , ...) | - kmalloc + kmalloc_array ( - (E1) * (E2) + E1, E2 , ...) | - kmalloc + kmalloc_array ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-04Merge branch 'locking-core-for-linus' of ↵Linus Torvalds7-236/+177
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - Lots of tidying up changes all across the map for Linux's formal memory/locking-model tooling, by Alan Stern, Akira Yokosawa, Andrea Parri, Paul E. McKenney and SeongJae Park. Notable changes beyond an overall update in the tooling itself is the tidying up of spin_is_locked() semantics, which spills over into the kernel proper as well. - qspinlock improvements: the locking algorithm now guarantees forward progress whereas the previous implementation in mainline could starve threads indefinitely in cmpxchg() loops. Also other related cleanups to the qspinlock code (Will Deacon) - misc smaller improvements, cleanups and fixes all across the locking subsystem * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits) locking/rwsem: Simplify the is-owner-spinnable checks tools/memory-model: Add reference for 'Simplifying ARM concurrency' tools/memory-model: Update ASPLOS information MAINTAINERS, tools/memory-model: Update e-mail address for Andrea Parri tools/memory-model: Fix coding style in 'lock.cat' tools/memory-model: Remove out-of-date comments and code from lock.cat tools/memory-model: Improve mixed-access checking in lock.cat tools/memory-model: Improve comments in lock.cat tools/memory-model: Remove duplicated code from lock.cat tools/memory-model: Flag "cumulativity" and "propagation" tests tools/memory-model: Add model support for spin_is_locked() tools/memory-model: Add scripts to test memory model tools/memory-model: Fix coding style in 'linux-kernel.def' tools/memory-model: Model 'smp_store_mb()' tools/memory-order: Update the cheat-sheet to show that smp_mb__after_atomic() orders later RMW operations tools/memory-order: Improve key for SELF and SV tools/memory-model: Fix cheat sheet typo tools/memory-model: Update required version of herdtools7 tools/memory-model: Redefine rb in terms of rcu-fence tools/memory-model: Rename link and rcu-path to rcu-link and rb ...
2018-06-04Merge branch 'hch.procfs' of ↵Linus Torvalds1-42/+3
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull procfs updates from Al Viro: "Christoph's proc_create_... cleanups series" * 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (44 commits) xfs, proc: hide unused xfs procfs helpers isdn/gigaset: add back gigaset_procinfo assignment proc: update SIZEOF_PDE_INLINE_NAME for the new pde fields tty: replace ->proc_fops with ->proc_show ide: replace ->proc_fops with ->proc_show ide: remove ide_driver_proc_write isdn: replace ->proc_fops with ->proc_show atm: switch to proc_create_seq_private atm: simplify procfs code bluetooth: switch to proc_create_seq_data netfilter/x_tables: switch to proc_create_seq_private netfilter/xt_hashlimit: switch to proc_create_{seq,single}_data neigh: switch to proc_create_seq_data hostap: switch to proc_create_{seq,single}_data bonding: switch to proc_create_seq_data rtc/proc: switch to proc_create_single_data drbd: switch to proc_create_single resource: switch to proc_create_seq_data staging/rtl8192u: simplify procfs code jfs: simplify procfs code ...
2018-05-25locking/rwsem: Simplify the is-owner-spinnable checksOleg Nesterov1-12/+13
Add the trivial owner_on_cpu() helper for rwsem_can_spin_on_owner() and rwsem_spin_on_owner(), it also allows to make rwsem_can_spin_on_owner() a bit more clear. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jan Kara <jack@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Theodore Y. Ts'o <tytso@mit.edu> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180518165534.GA22348@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-25Merge branch 'linus' into locking/core, to pick up fixesIngo Molnar3-21/+30
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-16locking/percpu-rwsem: Annotate rwsem ownership transfer by setting ↵Waiman Long1-0/+2
RWSEM_OWNER_UNKNOWN The filesystem freezing code needs to transfer ownership of a rwsem embedded in a percpu-rwsem from the task that does the freezing to another one that does the thawing by calling percpu_rwsem_release() after freezing and percpu_rwsem_acquire() before thawing. However, the new rwsem debug code runs afoul with this scheme by warning that the task that releases the rwsem isn't the one that acquires it, as reported by Amir Goldstein: DEBUG_LOCKS_WARN_ON(sem->owner != get_current()) WARNING: CPU: 1 PID: 1401 at /home/amir/build/src/linux/kernel/locking/rwsem.c:133 up_write+0x59/0x79 Call Trace: percpu_up_write+0x1f/0x28 thaw_super_locked+0xdf/0x120 do_vfs_ioctl+0x270/0x5f1 ksys_ioctl+0x52/0x71 __x64_sys_ioctl+0x16/0x19 do_syscall_64+0x5d/0x167 entry_SYSCALL_64_after_hwframe+0x49/0xbe To work properly with the rwsem debug code, we need to annotate that the rwsem ownership is unknown during the tranfer period until a brave soul comes forward to acquire the ownership. During that period, optimistic spinning will be disabled. Reported-by: Amir Goldstein <amir73il@gmail.com> Tested-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jan Kara <jack@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Theodore Y. Ts'o <tytso@mit.edu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-fsdevel@vger.kernel.org Link: http://lkml.kernel.org/r/1526420991-21213-3-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-16locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flagWaiman Long3-21/+28
There are use cases where a rwsem can be acquired by one task, but released by another task. In thess cases, optimistic spinning may need to be disabled. One example will be the filesystem freeze/thaw code where the task that freezes the filesystem will acquire a write lock on a rwsem and then un-owns it before returning to userspace. Later on, another task will come along, acquire the ownership, thaw the filesystem and release the rwsem. Bit 0 of the owner field was used to designate that it is a reader owned rwsem. It is now repurposed to mean that the owner of the rwsem is not known. If only bit 0 is set, the rwsem is reader owned. If bit 0 and other bits are set, it is writer owned with an unknown owner. One such value for the latter case is (-1L). So we can set owner to 1 for reader-owned, -1 for writer-owned. The owner is unknown in both cases. To handle transfer of rwsem ownership, the higher level code should set the owner field to -1 to indicate a write-locked rwsem with unknown owner. Optimistic spinning will be disabled in this case. Once the higher level code figures who the new owner is, it can then set the owner field accordingly. Tested-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jan Kara <jack@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Theodore Y. Ts'o <tytso@mit.edu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-fsdevel@vger.kernel.org Link: http://lkml.kernel.org/r/1526420991-21213-2-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-16proc: introduce proc_create_single{,_data}Christoph Hellwig1-15/+1
Variants of proc_create{,_data} that directly take a seq_file show callback and drastically reduces the boilerplate code in the callers. All trivial callers converted over. Signed-off-by: Christoph Hellwig <hch@lst.de>
2018-05-16proc: introduce proc_create_seq{,_data}Christoph Hellwig1-27/+2
Variants of proc_create{,_data} that directly take a struct seq_operations argument and drastically reduces the boilerplate code in the callers. All trivial callers converted over. Signed-off-by: Christoph Hellwig <hch@lst.de>
2018-05-14locking/lockdep: Move sanity check to inside lockdep_print_held_locks()Tetsuo Handa1-16/+13
Calling lockdep_print_held_locks() on a running thread is considered unsafe. Since all callers should follow that rule and the sanity check is not heavy, this patch moves the sanity check to inside lockdep_print_held_locks(). As a side effect of this patch, the number of locks held by running threads will be printed as well. This change will be preferable when we want to know which threads might be relevant to a problem but are unable to print any clues because that thread is running. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1523011279-8206-2-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14locking/lockdep: Use for_each_process_thread() for debug_show_all_locks()Tetsuo Handa1-35/+8
debug_show_all_locks() tries to grab the tasklist_lock for two seconds, but calling while_each_thread() without tasklist_lock held is not safe. See the following commit for more information: 4449a51a7c281602 ("vm_is_stack: use for_each_thread() rather then buggy while_each_thread()") Change debug_show_all_locks() from "do_each_thread()/while_each_thread() with possibility of missing tasklist_lock" to "for_each_process_thread() with RCU", and add a call to touch_all_softlockup_watchdogs() like show_state_filter() does. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1523011279-8206-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-04locking/mutex: Optimize __mutex_trylock_fast()Peter Zijlstra1-1/+2
Use try_cmpxchg to avoid the pointless TEST instruction.. And add the (missing) atomic_long_try_cmpxchg*() wrappery. On x86_64 this gives: 0000000000000710 <mutex_lock>: 0000000000000710 <mutex_lock>: 710: 65 48 8b 14 25 00 00 mov %gs:0x0,%rdx 710: 65 48 8b 14 25 00 00 mov %gs:0x0,%rdx 717: 00 00 717: 00 00 715: R_X86_64_32S current_task 715: R_X86_64_32S current_task 719: 31 c0 xor %eax,%eax 719: 31 c0 xor %eax,%eax 71b: f0 48 0f b1 17 lock cmpxchg %rdx,(%rdi) 71b: f0 48 0f b1 17 lock cmpxchg %rdx,(%rdi) 720: 48 85 c0 test %rax,%rax 720: 75 02 jne 724 <mutex_lock+0x14> 723: 75 02 jne 727 <mutex_lock+0x17> 722: f3 c3 repz retq 725: f3 c3 repz retq 724: eb da jmp 700 <__mutex_lock_slowpath> 727: eb d7 jmp 700 <__mutex_lock_slowpath> 726: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 729: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) 72d: 00 00 00 On ARM64 this gives: 000000000000638 <mutex_lock>: 0000000000000638 <mutex_lock>: 638: d5384101 mrs x1, sp_el0 638: d5384101 mrs x1, sp_el0 63c: d2800002 mov x2, #0x0 63c: d2800002 mov x2, #0x0 640: f9800011 prfm pstl1strm, [x0] 640: f9800011 prfm pstl1strm, [x0] 644: c85ffc03 ldaxr x3, [x0] 644: c85ffc03 ldaxr x3, [x0] 648: ca020064 eor x4, x3, x2 648: ca020064 eor x4, x3, x2 64c: b5000064 cbnz x4, 658 <mutex_lock+0x20> 64c: b5000064 cbnz x4, 658 <mutex_lock+0x20> 650: c8047c01 stxr w4, x1, [x0] 650: c8047c01 stxr w4, x1, [x0] 654: 35ffff84 cbnz w4, 644 <mutex_lock+0xc> 654: 35ffff84 cbnz w4, 644 <mutex_lock+0xc> 658: b40000c3 cbz x3, 670 <mutex_lock+0x38> 658: b5000043 cbnz x3, 660 <mutex_lock+0x28> 65c: a9bf7bfd stp x29, x30, [sp,#-16]! 65c: d65f03c0 ret 660: 910003fd mov x29, sp 660: a9bf7bfd stp x29, x30, [sp,#-16]! 664: 97ffffef bl 620 <__mutex_lock_slowpath> 664: 910003fd mov x29, sp 668: a8c17bfd ldp x29, x30, [sp],#16 668: 97ffffee bl 620 <__mutex_lock_slowpath> 66c: d65f03c0 ret 66c: a8c17bfd ldp x29, x30, [sp],#16 670: d65f03c0 ret 670: d65f03c0 ret Reported-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Remove duplicate clear_pending() function from PV codeWill Deacon1-5/+0
The native clear_pending() function is identical to the PV version, so the latter can simply be removed. This fixes the build for systems with >= 16K CPUs using the PV lock implementation. Reported-by: Waiman Long <longman@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/20180427101619.GB21705@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Add stat tracking for pending vs. slowpathWaiman Long3-12/+18
Currently, the qspinlock_stat code tracks only statistical counts in the PV qspinlock code. However, it may also be useful to track the number of locking operations done via the pending code vs. the MCS lock queue slowpath for the non-PV case. The qspinlock stat code is modified to do that. The stat counter pv_lock_slowpath is renamed to lock_slowpath so that it can be used by both the PV and non-PV cases. Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1524738868-31318-14-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Use try_cmpxchg() instead of cmpxchg() when lockingWill Deacon1-10/+9
When reaching the head of an uncontended queue on the qspinlock slow-path, using a try_cmpxchg() instead of a cmpxchg() operation to transition the lock work to _Q_LOCKED_VAL generates slightly better code for x86 and pretty much identical code for arm64. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-13-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb()Will Deacon1-16/+17
The qspinlock slowpath must ensure that the MCS node is fully initialised before it can be reached by another other CPU. This is currently enforced by using a RELEASE operation when updating the tail and also when linking the node into the waitqueue, since the control dependency off xchg_tail is insufficient to enforce sufficient ordering, see: 95bcade33a8a ("locking/qspinlock: Ensure node is initialised before updating prev->next") Back-to-back RELEASE operations may be expensive on some architectures, particularly those that implement them using fences under the hood. We can replace the two RELEASE operations with a single smp_wmb() fence and use RELAXED operations for the subsequent publishing of the node. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-12-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Use smp_cond_load_relaxed() to wait for next nodeWill Deacon1-4/+2
When a locker reaches the head of the queue and takes the lock, a concurrent locker may enqueue and force the lock holder to spin whilst its node->next field is initialised. Rather than open-code a READ_ONCE/cpu_relax() loop, this can be implemented using smp_cond_load_relaxed() instead. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-10-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/mcs: Use smp_cond_load_acquire() in MCS spin loopJason Low1-4/+6
For qspinlocks on ARM64, we would like to use WFE instead of purely spinning. Qspinlocks internally have lock contenders spin on an MCS lock. Update arch_mcs_spin_lock_contended() such that it uses the new smp_cond_load_acquire() so that ARM64 can also override this spin loop with its own implementation using WFE. On x86, this can also be cheaper than spinning on smp_load_acquire(). Signed-off-by: Jason Low <jason.low2@hp.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-9-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Use atomic_cond_read_acquire()Will Deacon1-6/+6
Rather than dig into the counter field of the atomic_t inside the qspinlock structure so that we can call smp_cond_load_acquire(), use atomic_cond_read_acquire() instead, which operates on the atomic_t directly. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-8-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Kill cmpxchg() loop when claiming lock from head of queueWill Deacon1-11/+8
When a queued locker reaches the head of the queue, it claims the lock by setting _Q_LOCKED_VAL in the lockword. If there isn't contention, it must also clear the tail as part of this operation so that subsequent lockers can avoid taking the slowpath altogether. Currently this is expressed as a cmpxchg() loop that practically only runs up to two iterations. This is confusing to the reader and unhelpful to the compiler. Rewrite the cmpxchg() loop without the loop, so that a failed cmpxchg() implies that there is contention and we just need to write to _Q_LOCKED_VAL without considering the rest of the lockword. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-7-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Remove unbounded cmpxchg() loop from locking slowpathWill Deacon2-49/+58
The qspinlock locking slowpath utilises a "pending" bit as a simple form of an embedded test-and-set lock that can avoid the overhead of explicit queuing in cases where the lock is held but uncontended. This bit is managed using a cmpxchg() loop which tries to transition the uncontended lock word from (0,0,0) -> (0,0,1) or (0,0,1) -> (0,1,1). Unfortunately, the cmpxchg() loop is unbounded and lockers can be starved indefinitely if the lock word is seen to oscillate between unlocked (0,0,0) and locked (0,0,1). This could happen if concurrent lockers are able to take the lock in the cmpxchg() loop without queuing and pass it around amongst themselves. This patch fixes the problem by unconditionally setting _Q_PENDING_VAL using atomic_fetch_or, and then inspecting the old value to see whether we need to spin on the current lock owner, or whether we now effectively hold the lock. The tricky scenario is when concurrent lockers end up queuing on the lock and the lock becomes available, causing us to see a lockword of (n,0,0). With pending now set, simply queuing could lead to deadlock as the head of the queue may not have observed the pending flag being cleared. Conversely, if the head of the queue did observe pending being cleared, then it could transition the lock from (n,0,0) -> (0,0,1) meaning that any attempt to "undo" our setting of the pending bit could race with a concurrent locker trying to set it. We handle this race by preserving the pending bit when taking the lock after reaching the head of the queue and leaving the tail entry intact if we saw pending set, because we know that the tail is going to be updated shortly. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-6-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Bound spinning on pending->locked transition in slowpathWill Deacon1-3/+17
If a locker taking the qspinlock slowpath reads a lock value indicating that only the pending bit is set, then it will spin whilst the concurrent pending->locked transition takes effect. Unfortunately, there is no guarantee that such a transition will ever be observed since concurrent lockers could continuously set pending and hand over the lock amongst themselves, leading to starvation. Whilst this would probably resolve in practice, it means that it is not possible to prove liveness properties about the lock and means that lock acquisition time is unbounded. Rather than removing the pending->locked spinning from the slowpath altogether (which has been shown to heavily penalise a 2-threaded locking stress test on x86), this patch replaces the explicit spinning with a call to atomic_cond_read_relaxed and allows the architecture to provide a bound on the number of spins. For architectures that can respond to changes in cacheline state in their smp_cond_load implementation, it should be sufficient to use the default bound of 1. Suggested-by: Waiman Long <longman@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-4-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-27locking/qspinlock: Merge 'struct __qspinlock' into 'struct qspinlock'Will Deacon2-66/+14
'struct __qspinlock' provides a handy union of fields so that subcomponents of the lockword can be accessed by name, without having to manage shifts and masks explicitly and take endianness into account. This is useful in qspinlock.h and also potentially in arch headers, so move the 'struct __qspinlock' into 'struct qspinlock' and kill the extra definition. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Acked-by: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-3-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-31locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatchesWaiman Long2-1/+11
For a rwsem, locking can either be exclusive or shared. The corresponding exclusive or shared unlock must be used. Otherwise, the protected data structures may get corrupted or the lock may be in an inconsistent state. In order to detect such anomaly, a new configuration option DEBUG_RWSEMS is added which can be enabled to look for such mismatches and print warnings that that happens. Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1522445280-7767-2-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-31Merge branch 'linus' into locking/core, to pick up fixesIngo Molnar1-7/+30
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-29lockdep: Make the lock debug output more usefulTetsuo Handa1-2/+2
The lock debug output in print_lock() has a few shortcomings: - It prints the hlock->acquire_ip field in %px and %pS format. That's redundant information. - It lacks information about the lock object itself. The lock class is not helpful to identify a particular instance of a lock. Change the output so it prints: - hlock->instance to allow identification of a particular lock instance. - only the %pS format of hlock->ip_acquire which is sufficient to decode the actual code line with faddr2line. The resulting output is: 3 locks held by a.out/31106: #0: 00000000b0f753ba (&mm->mmap_sem){++++}, at: copy_process.part.41+0x10d5/0x1fe0 #1: 00000000ef64d539 (&mm->mmap_sem/1){+.+.}, at: copy_process.part.41+0x10fe/0x1fe0 #2: 00000000b41a282e (&mapping->i_mmap_rwsem){++++}, at: copy_process.part.41+0x12f2/0x1fe0 [ tglx: Massaged changelog ] Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: linux-mm@kvack.org Cc: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/201803271941.GBE57310.tVSOJLQOFFOHFM@I-love.SAKURA.ne.jp
2018-03-28locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()Peter Zijlstra2-7/+7
In -RT task_blocks_on_rt_mutex() may return with -EAGAIN due to (->pi_blocked_on == PI_WAKEUP_INPROGRESS) before it added itself as a waiter. In such a case remove_waiter() must not be called because without a waiter it will trigger the BUG_ON() statement. This was initially reported by Yimin Deng. Thomas Gleixner fixed it then with an explicit check for waiters before calling remove_waiter(). Instead of an explicit NULL check before calling rt_mutex_top_waiter() make the function return NULL if there are no waiters. With that fixed the now pointless NULL check is removed from rt_mutex_slowlock(). Reported-and-debugged-by: Yimin Deng <yimin11.deng@gmail.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/CAAh1qt=DCL9aUXNxanP5BKtiPp3m+qj4yB+gDohhXPVFCxWwzg@mail.gmail.com Link: https://lkml.kernel.org/r/20180327121438.sss7hxg3crqy4ecd@linutronix.de
2018-03-20locking/mutex: Improve documentationMatthew Wilcox1-7/+30
On Wed, Mar 14, 2018 at 01:56:31PM -0700, Andrew Morton wrote: > My memory is weak and our documentation is awful. What does > mutex_lock_killable() actually do and how does it differ from > mutex_lock_interruptible()? Add kernel-doc for mutex_lock_killable() and mutex_lock_io(). Reword the kernel-doc for mutex_lock_interruptible(). Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: cl@linux.com Cc: tj@kernel.org Link: http://lkml.kernel.org/r/20180315115812.GA9949@bombadil.infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-12Merge tag 'v4.16-rc5' into locking/core, to pick up fixesIngo Molnar1-2/+3
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-09rtmutex: Make rt_mutex_futex_unlock() safe for irq-off callsitesBoqun Feng1-2/+3
When running rcutorture with TREE03 config, CONFIG_PROVE_LOCKING=y, and kernel cmdline argument "rcutorture.gp_exp=1", lockdep reports a HARDIRQ-safe->HARDIRQ-unsafe deadlock: ================================ WARNING: inconsistent lock state 4.16.0-rc4+ #1 Not tainted -------------------------------- inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. takes: __schedule+0xbe/0xaf0 {IN-HARDIRQ-W} state was registered at: _raw_spin_lock+0x2a/0x40 scheduler_tick+0x47/0xf0 ... other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rq->lock); <Interrupt> lock(&rq->lock); *** DEADLOCK *** 1 lock held by rcu_torture_rea/724: rcu_torture_read_lock+0x0/0x70 stack backtrace: CPU: 2 PID: 724 Comm: rcu_torture_rea Not tainted 4.16.0-rc4+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014 Call Trace: lock_acquire+0x90/0x200 ? __schedule+0xbe/0xaf0 _raw_spin_lock+0x2a/0x40 ? __schedule+0xbe/0xaf0 __schedule+0xbe/0xaf0 preempt_schedule_irq+0x2f/0x60 retint_kernel+0x1b/0x2d RIP: 0010:rcu_read_unlock_special+0x0/0x680 ? rcu_torture_read_unlock+0x60/0x60 __rcu_read_unlock+0x64/0x70 rcu_torture_read_unlock+0x17/0x60 rcu_torture_reader+0x275/0x450 ? rcutorture_booster_init+0x110/0x110 ? rcu_torture_stall+0x230/0x230 ? kthread+0x10e/0x130 kthread+0x10e/0x130 ? kthread_create_worker_on_cpu+0x70/0x70 ? call_usermodehelper_exec_async+0x11a/0x150 ret_from_fork+0x3a/0x50 This happens with the following even sequence: preempt_schedule_irq(); local_irq_enable(); __schedule(): local_irq_disable(); // irq off ... rcu_note_context_switch(): rcu_note_preempt_context_switch(): rcu_read_unlock_special(): local_irq_save(flags); ... raw_spin_unlock_irqrestore(...,flags); // irq remains off rt_mutex_futex_unlock(): raw_spin_lock_irq(); ... raw_spin_unlock_irq(); // accidentally set irq on <return to __schedule()> rq_lock(): raw_spin_lock(); // acquiring rq->lock with irq on which means rq->lock becomes a HARDIRQ-unsafe lock, which can cause deadlocks in scheduler code. This problem was introduced by commit 02a7c234e540 ("rcu: Suppress lockdep false-positive ->boost_mtx complaints"). That brought the user of rt_mutex_futex_unlock() with irq off. To fix this, replace the *lock_irq() in rt_mutex_futex_unlock() with *lock_irq{save,restore}() to make it safe to call rt_mutex_futex_unlock() with irq off. Fixes: 02a7c234e540 ("rcu: Suppress lockdep false-positive ->boost_mtx complaints") Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/20180309065630.8283-1-boqun.feng@gmail.com
2018-02-28locking/lockdep: Show unadorned pointersBorislav Petkov1-12/+12
Show unadorned pointers in lockdep reports - lockdep is a debugging facility and hashing pointers there doesn't make a whole lotta sense. Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20180226134926.23069-1-bp@alien8.de
2018-02-13locking/qspinlock: Ensure node->count is updated before initialising nodeWill Deacon1-0/+8
When queuing on the qspinlock, the count field for the current CPU's head node is incremented. This needn't be atomic because locking in e.g. IRQ context is balanced and so an IRQ will return with node->count as it found it. However, the compiler could in theory reorder the initialisation of node[idx] before the increment of the head node->count, causing an IRQ to overwrite the initialised node and potentially corrupt the lock state. Avoid the potential for this harmful compiler reordering by placing a barrier() between the increment of the head node->count and the subsequent node initialisation. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1518528177-19169-3-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-13locking/qspinlock: Ensure node is initialised before updating prev->nextWill Deacon1-6/+7
When a locker ends up queuing on the qspinlock locking slowpath, we initialise the relevant mcs node and publish it indirectly by updating the tail portion of the lock word using xchg_tail. If we find that there was a pre-existing locker in the queue, we subsequently update their ->next field to point at our node so that we are notified when it's our turn to take the lock. This can be roughly illustrated as follows: /* Initialise the fields in node and encode a pointer to node in tail */ tail = initialise_node(node); /* * Exchange tail into the lockword using an atomic read-modify-write * operation with release semantics */ old = xchg_tail(lock, tail); /* If there was a pre-existing waiter ... */ if (old & _Q_TAIL_MASK) { prev = decode_tail(old); smp_read_barrier_depends(); /* ... then update their ->next field to point to node. WRITE_ONCE(prev->next, node); } The conditional update of prev->next therefore relies on the address dependency from the result of xchg_tail ensuring order against the prior initialisation of node. However, since the release semantics of the xchg_tail operation apply only to the write portion of the RmW, then this ordering is not guaranteed and it is possible for the CPU to return old before the writes to node have been published, consequently allowing us to point prev->next to an uninitialised node. This patch fixes the problem by making the update of prev->next a RELEASE operation, which also removes the reliance on dependency ordering. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1518528177-19169-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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