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2021-06-18sched: Introduce task_is_running()Peter Zijlstra1-1/+1
Replace a bunch of 'p->state == TASK_RUNNING' with a new helper: task_is_running(p). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210611082838.222401495@infradead.org
2021-05-18locking/lockdep: Correct calling tracepointsLeo Yan1-2/+2
The commit eb1f00237aca ("lockdep,trace: Expose tracepoints") reverses tracepoints for lock_contended() and lock_acquired(), thus the ftrace log shows the wrong locking sequence that "acquired" event is prior to "contended" event: <idle>-0 [001] d.s3 20803.501685: lock_acquire: 0000000008b91ab4 &sg_policy->update_lock <idle>-0 [001] d.s3 20803.501686: lock_acquired: 0000000008b91ab4 &sg_policy->update_lock <idle>-0 [001] d.s3 20803.501689: lock_contended: 0000000008b91ab4 &sg_policy->update_lock <idle>-0 [001] d.s3 20803.501690: lock_release: 0000000008b91ab4 &sg_policy->update_lock This patch fixes calling tracepoints for lock_contended() and lock_acquired(). Fixes: eb1f00237aca ("lockdep,trace: Expose tracepoints") Signed-off-by: Leo Yan <leo.yan@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210512120937.90211-1-leo.yan@linaro.org
2021-04-28Merge tag 'locking-core-2021-04-28' of ↵Linus Torvalds1-7/+12
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - rtmutex cleanup & spring cleaning pass that removes ~400 lines of code - Futex simplifications & cleanups - Add debugging to the CSD code, to help track down a tenacious race (or hw problem) - Add lockdep_assert_not_held(), to allow code to require a lock to not be held, and propagate this into the ath10k driver - Misc LKMM documentation updates - Misc KCSAN updates: cleanups & documentation updates - Misc fixes and cleanups - Fix locktorture bugs with ww_mutexes * tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) kcsan: Fix printk format string static_call: Relax static_call_update() function argument type static_call: Fix unused variable warn w/o MODULE locking/rtmutex: Clean up signal handling in __rt_mutex_slowlock() locking/rtmutex: Restrict the trylock WARN_ON() to debug locking/rtmutex: Fix misleading comment in rt_mutex_postunlock() locking/rtmutex: Consolidate the fast/slowpath invocation locking/rtmutex: Make text section and inlining consistent locking/rtmutex: Move debug functions as inlines into common header locking/rtmutex: Decrapify __rt_mutex_init() locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs locking/rtmutex: Inline chainwalk depth check locking/rtmutex: Move rt_mutex_debug_task_free() to rtmutex.c locking/rtmutex: Remove empty and unused debug stubs locking/rtmutex: Consolidate rt_mutex_init() locking/rtmutex: Remove output from deadlock detector locking/rtmutex: Remove rtmutex deadlock tester leftovers locking/rtmutex: Remove rt_mutex_timed_lock() MAINTAINERS: Add myself as futex reviewer locking/mutex: Remove repeated declaration ...
2021-04-26Merge tag 'tomoyo-pr-20210426' of git://git.osdn.net/gitroot/tomoyo/tomoyo-test1Linus Torvalds1-1/+1
Pull lockdep capacity limit updates from Tetsuo Handa: "syzbot is occasionally reporting that fuzz testing is terminated due to hitting upper limits lockdep can track. Analysis via /proc/lockdep* did not show any obvious culprits, allow tuning tracing capacity constants" * tag 'tomoyo-pr-20210426' of git://git.osdn.net/gitroot/tomoyo/tomoyo-test1: lockdep: Allow tuning tracing capacity constants.
2021-04-05lockdep: Allow tuning tracing capacity constants.Tetsuo Handa1-1/+1
Since syzkaller continues various test cases until the kernel crashes, syzkaller tends to examine more locking dependencies than normal systems. As a result, syzbot is reporting that the fuzz testing was terminated due to hitting upper limits lockdep can track [1] [2] [3]. Since analysis via /proc/lockdep* did not show any obvious culprit [4] [5], we have no choice but allow tuning tracing capacity constants. [1] https://syzkaller.appspot.com/bug?id=3d97ba93fb3566000c1c59691ea427370d33ea1b [2] https://syzkaller.appspot.com/bug?id=381cb436fe60dc03d7fd2a092b46d7f09542a72a [3] https://syzkaller.appspot.com/bug?id=a588183ac34c1437fc0785e8f220e88282e5a29f [4] https://lkml.kernel.org/r/4b8f7a57-fa20-47bd-48a0-ae35d860f233@i-love.sakura.ne.jp [5] https://lkml.kernel.org/r/1c351187-253b-2d49-acaf-4563c63ae7d2@i-love.sakura.ne.jp References: https://lkml.kernel.org/r/1595640639-9310-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Dmitry Vyukov <dvyukov@google.com>
2021-03-22lockdep: Address clang -Wformat warning printing for %hdArnd Bergmann1-1/+1
Clang doesn't like format strings that truncate a 32-bit value to something shorter: kernel/locking/lockdep.c:709:4: error: format specifies type 'short' but the argument has type 'int' [-Werror,-Wformat] In this case, the warning is a slightly questionable, as it could realize that both class->wait_type_outer and class->wait_type_inner are in fact 8-bit struct members, even though the result of the ?: operator becomes an 'int'. However, there is really no point in printing the number as a 16-bit 'short' rather than either an 8-bit or 32-bit number, so just change it to a normal %d. Fixes: de8f5e4f2dc1 ("lockdep: Introduce wait-type checks") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210322115531.3987555-1-arnd@kernel.org
2021-03-22locking: Fix typos in commentsIngo Molnar1-2/+2
Fix ~16 single-word typos in locking code comments. Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-03-21lockdep: Add a missing initialization hint to the "INFO: Trying to register ↵Tetsuo Handa1-1/+2
non-static key" message Since this message is printed when dynamically allocated spinlocks (e.g. kzalloc()) are used without initialization (e.g. spin_lock_init()), suggest to developers to check whether initialization functions for objects were called, before making developers wonder what annotation is missing. [ mingo: Minor tweaks to the message. ] Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210321064913.4619-1-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-03-06lockdep: Add lockdep lock state definesShuah Khan1-5/+6
Adds defines for lock state returns from lock_is_held_type() based on Johannes Berg's suggestions as it make it easier to read and maintain the lock states. These are defines and a enum to avoid changes to lock_is_held_type() and lockdep_is_held() return types. Updates to lock_is_held_type() and __lock_is_held() to use the new defines. Signed-off-by: Shuah Khan <skhan@linuxfoundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@codeaurora.org/
2021-03-06lockdep: Add lockdep_assert_not_held()Shuah Khan1-1/+5
Some kernel functions must be called without holding a specific lock. Add lockdep_assert_not_held() to be used in these functions to detect incorrect calls while holding a lock. lockdep_assert_not_held() provides the opposite functionality of lockdep_assert_held() which is used to assert calls that require holding a specific lock. Incorporates suggestions from Peter Zijlstra to avoid misfires when lockdep_off() is employed. The need for lockdep_assert_not_held() came up in a discussion on ath10k patch. ath10k_drain_tx() and i915_vma_pin_ww() are examples of functions that can use lockdep_assert_not_held(). Signed-off-by: Shuah Khan <skhan@linuxfoundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@codeaurora.org/
2021-02-12Merge branch 'linus' into locking/core, to pick up upstream fixesIngo Molnar1-2/+7
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-02-05locking/lockdep: Avoid unmatched unlockPeter Zijlstra1-1/+2
Commit f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") overlooked that print_usage_bug() releases the graph_lock and called it without the graph lock held. Fixes: f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Link: https://lkml.kernel.org/r/YBfkuyIfB1+VRxXP@hirez.programming.kicks-ass.net
2021-01-14locking/lockdep: Exclude local_lock_t from IRQ inversionsBoqun Feng1-4/+53
The purpose of local_lock_t is to abstract: preempt_disable() / local_bh_disable() / local_irq_disable(). These are the traditional means of gaining access to per-cpu data, but are fundamentally non-preemptible. local_lock_t provides a per-cpu lock, that on !PREEMPT_RT reduces to no-ops, just like regular spinlocks do on UP. This gives rise to: CPU0 CPU1 local_lock(B) spin_lock_irq(A) <IRQ> spin_lock(A) local_lock(B) Where lockdep then figures things will lock up; which would be true if B were any other kind of lock. However this is a false positive, no such deadlock actually exists. For !RT the above local_lock(B) is preempt_disable(), and there's obviously no deadlock; alternatively, CPU0's B != CPU1's B. For RT the argument is that since local_lock() nests inside spin_lock(), it cannot be used in hardirq context, and therefore CPU0 cannot in fact happen. Even though B is a real lock, it is a preemptible lock and any threaded-irq would simply schedule out and let the preempted task (which holds B) continue such that the task on CPU1 can make progress, after which the threaded-irq resumes and can finish. This means that we can never form an IRQ inversion on a local_lock dependency, so terminate the graph walk when looking for IRQ inversions when we encounter one. One consequence is that (for LOCKDEP_SMALL) when we look for redundant dependencies, A -> B is not redundant in the presence of A -> L -> B. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> [peterz: Changelog] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-01-14locking/lockdep: Clean up check_redundant() a bitPeter Zijlstra1-42/+49
In preparation for adding an TRACE_IRQFLAGS dependent skip function to check_redundant(), move it below the TRACE_IRQFLAGS #ifdef. While there, provide a stub function to reduce #ifdef usage. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-01-14locking/lockdep: Add a skip() function to __bfs()Boqun Feng1-10/+19
Some __bfs() walks will have additional iteration constraints (beyond the path being strong). Provide an additional function to allow terminating graph walks. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-01-14locking/lockdep: Mark local_lock_tPeter Zijlstra1-7/+9
The local_lock_t's are special, because they cannot form IRQ inversions, make sure we can tell them apart from the rest of the locks. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-01-12locking/lockdep: Avoid noinstr warning for DEBUG_LOCKDEPPeter Zijlstra1-1/+6
vmlinux.o: warning: objtool: lock_is_held_type()+0x60: call to check_flags.part.0() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210106144017.652218215@infradead.org
2021-01-12locking/lockdep: Cure noinstr failPeter Zijlstra1-1/+1
When the compiler doesn't feel like inlining, it causes a noinstr fail: vmlinux.o: warning: objtool: lock_is_held_type()+0xb: call to lockdep_enabled() leaves .noinstr.text section Fixes: 4d004099a668 ("lockdep: Fix lockdep recursion") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210106144017.592595176@infradead.org
2020-11-17lockdep: Put graph lock/unlock under lock_recursion protectionBoqun Feng1-2/+4
A warning was hit when running xfstests/generic/068 in a Hyper-V guest: [...] ------------[ cut here ]------------ [...] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled()) [...] WARNING: CPU: 2 PID: 1350 at kernel/locking/lockdep.c:5280 check_flags.part.0+0x165/0x170 [...] ... [...] Workqueue: events pwq_unbound_release_workfn [...] RIP: 0010:check_flags.part.0+0x165/0x170 [...] ... [...] Call Trace: [...] lock_is_held_type+0x72/0x150 [...] ? lock_acquire+0x16e/0x4a0 [...] rcu_read_lock_sched_held+0x3f/0x80 [...] __send_ipi_one+0x14d/0x1b0 [...] hv_send_ipi+0x12/0x30 [...] __pv_queued_spin_unlock_slowpath+0xd1/0x110 [...] __raw_callee_save___pv_queued_spin_unlock_slowpath+0x11/0x20 [...] .slowpath+0x9/0xe [...] lockdep_unregister_key+0x128/0x180 [...] pwq_unbound_release_workfn+0xbb/0xf0 [...] process_one_work+0x227/0x5c0 [...] worker_thread+0x55/0x3c0 [...] ? process_one_work+0x5c0/0x5c0 [...] kthread+0x153/0x170 [...] ? __kthread_bind_mask+0x60/0x60 [...] ret_from_fork+0x1f/0x30 The cause of the problem is we have call chain lockdep_unregister_key() -> <irq disabled by raw_local_irq_save()> lockdep_unlock() -> arch_spin_unlock() -> __pv_queued_spin_unlock_slowpath() -> pv_kick() -> __send_ipi_one() -> trace_hyperv_send_ipi_one(). Although this particular warning is triggered because Hyper-V has a trace point in ipi sending, but in general arch_spin_unlock() may call another function having a trace point in it, so put the arch_spin_lock() and arch_spin_unlock() after lock_recursion protection to fix this problem and avoid similiar problems. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201113110512.1056501-1-boqun.feng@gmail.com
2020-11-10lockdep: Avoid to modify chain keys in validate_chain()Boqun Feng1-10/+9
Chris Wilson reported a problem spotted by check_chain_key(): a chain key got changed in validate_chain() because we modify the ->read in validate_chain() to skip checks for dependency adding, and ->read is taken into calculation for chain key since commit f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey"). Fix this by avoiding to modify ->read in validate_chain() based on two facts: a) since we now support recursive read lock detection, there is no need to skip checks for dependency adding for recursive readers, b) since we have a), there is only one case left (nest_lock) where we want to skip checks in validate_chain(), we simply remove the modification for ->read and rely on the return value of check_deadlock() to skip the dependency adding. Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201102053743.450459-1-boqun.feng@gmail.com
2020-10-30lockdep: Fix nr_unused_locks accountingPeter Zijlstra1-10/+4
Chris reported that commit 24d5a3bffef1 ("lockdep: Fix usage_traceoverflow") breaks the nr_unused_locks validation code triggered by /proc/lockdep_stats. By fully splitting LOCK_USED and LOCK_USED_READ it becomes a bad indicator for accounting nr_unused_locks; simplyfy by using any first bit. Fixes: 24d5a3bffef1 ("lockdep: Fix usage_traceoverflow") Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://lkml.kernel.org/r/20201027124834.GL2628@hirez.programming.kicks-ass.net
2020-10-30locking/lockdep: Remove more raw_cpu_read() usagePeter Zijlstra1-1/+1
I initially thought raw_cpu_read() was OK, since if it is !0 we have IRQs disabled and can't get migrated, so if we get migrated both CPUs must have 0 and it doesn't matter which 0 we read. And while that is true; it isn't the whole store, on pretty much all architectures (except x86) this can result in computing the address for one CPU, getting migrated, the old CPU continuing execution with another task (possibly setting recursion) and then the new CPU reading the value of the old CPU, which is no longer 0. Similer to: baffd723e44d ("lockdep: Revert "lockdep: Use raw_cpu_*() for per-cpu variables"") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201026152256.GB2651@hirez.programming.kicks-ass.net
2020-10-22lockdep: Fix preemption WARN for spurious IRQ-enablePeter Zijlstra1-2/+2
It is valid (albeit uncommon) to call local_irq_enable() without first having called local_irq_disable(). In this case we enter lockdep_hardirqs_on*() with IRQs enabled and trip a preemption warning for using __this_cpu_read(). Use this_cpu_read() instead to avoid the warning. Fixes: 4d004099a6 ("lockdep: Fix lockdep recursion") Reported-by: syzbot+53f8ce8bbc07924b6417@syzkaller.appspotmail.com Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-10-09Merge branch 'locking/urgent' into locking/core, to pick up fixesIngo Molnar1-52/+92
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-10-09lockdep: Fix lockdep recursionPeter Zijlstra1-40/+59
Steve reported that lockdep_assert*irq*(), when nested inside lockdep itself, will trigger a false-positive. One example is the stack-trace code, as called from inside lockdep, triggering tracing, which in turn calls RCU, which then uses lockdep_assert_irqs_disabled(). Fixes: a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-10-09lockdep: Fix usage_traceoverflowPeter Zijlstra1-17/+15
Basically print_lock_class_header()'s for loop is out of sync with the the size of of ->usage_traces[]. Also clean things up a bit while at it, to avoid such mishaps in the future. Fixes: 23870f122768 ("locking/lockdep: Fix "USED" <- "IN-NMI" inversions") Reported-by: Qian Cai <cai@redhat.com> Debugged-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Qian Cai <cai@redhat.com> Link: https://lkml.kernel.org/r/20200930094937.GE2651@hirez.programming.kicks-ass.net
2020-09-29lockdep: Optimize the memory usage of circular queueBoqun Feng1-39/+60
Qian Cai reported a BFS_EQUEUEFULL warning [1] after read recursive deadlock detection merged into tip tree recently. Unlike the previous lockep graph searching, which iterate every lock class (every node in the graph) exactly once, the graph searching for read recurisve deadlock detection needs to iterate every lock dependency (every edge in the graph) once, as a result, the maximum memory cost of the circular queue changes from O(V), where V is the number of lock classes (nodes or vertices) in the graph, to O(E), where E is the number of lock dependencies (edges), because every lock class or dependency gets enqueued once in the BFS. Therefore we hit the BFS_EQUEUEFULL case. However, actually we don't need to enqueue all dependencies for the BFS, because every time we enqueue a dependency, we almostly enqueue all other dependencies in the same dependency list ("almostly" is because we currently check before enqueue, so if a dependency doesn't pass the check stage we won't enqueue it, however, we can always do in reverse ordering), based on this, we can only enqueue the first dependency from a dependency list and every time we want to fetch a new dependency to work, we can either: 1) fetch the dependency next to the current dependency in the dependency list or 2) if the dependency in 1) doesn't exist, fetch the dependency from the queue. With this approach, the "max bfs queue depth" for a x86_64_defconfig + lockdep and selftest config kernel can get descreased from: max bfs queue depth: 201 to (after apply this patch) max bfs queue depth: 61 While I'm at it, clean up the code logic a little (e.g. directly return other than set a "ret" value and goto the "exit" label). [1]: https://lore.kernel.org/lkml/17343f6f7f2438fc376125384133c5ba70c2a681.camel@redhat.com/ Reported-by: Qian Cai <cai@redhat.com> Reported-by: syzbot+62ebe501c1ce9a91f68c@syzkaller.appspotmail.com Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200917080210.108095-1-boqun.feng@gmail.com
2020-09-03locking/lockdep: Fix "USED" <- "IN-NMI" inversionspeterz@infradead.org1-6/+29
During the LPC RCU BoF Paul asked how come the "USED" <- "IN-NMI" detector doesn't trip over rcu_read_lock()'s lockdep annotation. Looking into this I found a very embarrasing typo in verify_lock_unused(): - if (!(class->usage_mask & LOCK_USED)) + if (!(class->usage_mask & LOCKF_USED)) fixing that will indeed cause rcu_read_lock() to insta-splat :/ The above typo means that instead of testing for: 0x100 (1 << LOCK_USED), we test for 8 (LOCK_USED), which corresponds to (1 << LOCK_ENABLED_HARDIRQ). So instead of testing for _any_ used lock, it will only match any lock used with interrupts enabled. The rcu_read_lock() annotation uses .check=0, which means it will not set any of the interrupt bits and will thus never match. In order to properly fix the situation and allow rcu_read_lock() to correctly work, split LOCK_USED into LOCK_USED and LOCK_USED_READ and by having .read users set USED_READ and test USED, pure read-recursive locks are permitted. Fixes: f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/r/20200902160323.GK1362448@hirez.programming.kicks-ass.net
2020-08-26lockdep: Take read/write status in consideration when generate chainkeyBoqun Feng1-18/+35
Currently, the chainkey of a lock chain is a hash sum of the class_idx of all the held locks, the read/write status are not taken in to consideration while generating the chainkey. This could result into a problem, if we have: P1() { read_lock(B); lock(A); } P2() { lock(A); read_lock(B); } P3() { lock(A); write_lock(B); } , and P1(), P2(), P3() run one by one. And when running P2(), lockdep detects such a lock chain A -> B is not a deadlock, then it's added in the chain cache, and then when running P3(), even if it's a deadlock, we could miss it because of the hit of chain cache. This could be confirmed by self testcase "chain cached mixed R-L/L-W ". To resolve this, we use concept "hlock_id" to generate the chainkey, the hlock_id is a tuple (hlock->class_idx, hlock->read), which fits in a u16 type. With this, the chainkeys are different is the lock sequences have the same locks but different read/write status. Besides, since we use "hlock_id" to generate chainkeys, the chain_hlocks array now store the "hlock_id"s rather than lock_class indexes. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-15-boqun.feng@gmail.com
2020-08-26lockdep: Add recursive read locks into dependency graphBoqun Feng1-17/+2
Since we have all the fundamental to handle recursive read locks, we now add them into the dependency graph. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-13-boqun.feng@gmail.com
2020-08-26lockdep: Fix recursive read lock related safe->unsafe detectionBoqun Feng1-47/+141
Currently, in safe->unsafe detection, lockdep misses the fact that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ usage may cause deadlock too, for example: P1 P2 <irq disabled> write_lock(l1); <irq enabled> read_lock(l2); write_lock(l2); <in irq> read_lock(l1); Actually, all of the following cases may cause deadlocks: LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_* LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_* LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ To fix this, we need to 1) change the calculation of exclusive_mask() so that READ bits are not dropped and 2) always call usage() in mark_lock_irq() to check usage deadlocks, even when the new usage of the lock is READ. Besides, adjust usage_match() and usage_acculumate() to recursive read lock changes. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-12-boqun.feng@gmail.com
2020-08-26lockdep: Adjust check_redundant() for recursive read changeBoqun Feng1-3/+44
check_redundant() will report redundancy if it finds a path could replace the about-to-add dependency in the BFS search. With recursive read lock changes, we certainly need to change the match function for the check_redundant(), because the path needs to match not only the lock class but also the dependency kinds. For example, if the about-to-add dependency @prev -> @next is A -(SN)-> B, and we find a path A -(S*)-> .. -(*R)->B in the dependency graph with __bfs() (for simplicity, we can also say we find an -(SR)-> path from A to B), we can not replace the dependency with that path in the BFS search. Because the -(SN)-> dependency can make a strong path with a following -(S*)-> dependency, however an -(SR)-> path cannot. Further, we can replace an -(SN)-> dependency with a -(EN)-> path, that means if we find a path which is stronger than or equal to the about-to-add dependency, we can report the redundancy. By "stronger", it means both the start and the end of the path are not weaker than the start and the end of the dependency (E is "stronger" than S and N is "stronger" than R), so that we can replace the dependency with that path. To make sure we find a path whose start point is not weaker than the about-to-add dependency, we use a trick: the ->only_xr of the root (start point) of __bfs() is initialized as @prev-> == 0, therefore if @prev is E, __bfs() will pick only -(E*)-> for the first dependency, otherwise, __bfs() can pick -(E*)-> or -(S*)-> for the first dependency. To make sure we find a path whose end point is not weaker than the about-to-add dependency, we replace the match function for __bfs() check_redundant(), we check for the case that either @next is R (anything is not weaker than it) or the end point of the path is N (which is not weaker than anything). Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-11-boqun.feng@gmail.com
2020-08-26lockdep: Support deadlock detection for recursive read locks in ↵Boqun Feng1-8/+35
check_noncircular() Currently, lockdep only has limit support for deadlock detection for recursive read locks. This patch support deadlock detection for recursive read locks. The basic idea is: We are about to add dependency B -> A in to the dependency graph, we use check_noncircular() to find whether we have a strong dependency path A -> .. -> B so that we have a strong dependency circle (a closed strong dependency path): A -> .. -> B -> A , which doesn't have two adjacent dependencies as -(*R)-> L -(S*)->. Since A -> .. -> B is already a strong dependency path, so if either B -> A is -(E*)-> or A -> .. -> B is -(*N)->, the circle A -> .. -> B -> A is strong, otherwise not. So we introduce a new match function hlock_conflict() to replace the class_equal() for the deadlock check in check_noncircular(). Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-10-boqun.feng@gmail.com
2020-08-26lockdep: Make __bfs(.match) return boolBoqun Feng1-10/+10
The "match" parameter of __bfs() is used for checking whether we hit a match in the search, therefore it should return a boolean value rather than an integer for better readability. This patch then changes the return type of the function parameter and the match functions to bool. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-9-boqun.feng@gmail.com
2020-08-26lockdep: Extend __bfs() to work with multiple types of dependenciesBoqun Feng1-19/+94
Now we have four types of dependencies in the dependency graph, and not all the pathes carry real dependencies (the dependencies that may cause a deadlock), for example: Given lock A and B, if we have: CPU1 CPU2 ============= ============== write_lock(A); read_lock(B); read_lock(B); write_lock(A); (assuming read_lock(B) is a recursive reader) then we have dependencies A -(ER)-> B, and B -(SN)-> A, and a dependency path A -(ER)-> B -(SN)-> A. In lockdep w/o recursive locks, a dependency path from A to A means a deadlock. However, the above case is obviously not a deadlock, because no one holds B exclusively, therefore no one waits for the other to release B, so who get A first in CPU1 and CPU2 will run non-blockingly. As a result, dependency path A -(ER)-> B -(SN)-> A is not a real/strong dependency that could cause a deadlock. From the observation above, we know that for a dependency path to be real/strong, no two adjacent dependencies can be as -(*R)-> -(S*)->. Now our mission is to make __bfs() traverse only the strong dependency paths, which is simple: we record whether we only have -(*R)-> for the previous lock_list of the path in lock_list::only_xr, and when we pick a dependency in the traverse, we 1) filter out -(S*)-> dependency if the previous lock_list only has -(*R)-> dependency (i.e. ->only_xr is true) and 2) set the next lock_list::only_xr to true if we only have -(*R)-> left after we filter out dependencies based on 1), otherwise, set it to false. With this extension for __bfs(), we now need to initialize the root of __bfs() properly (with a correct ->only_xr), to do so, we introduce some helper functions, which also cleans up a little bit for the __bfs() root initialization code. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-8-boqun.feng@gmail.com
2020-08-26lockdep: Introduce lock_list::depBoqun Feng1-4/+88
To add recursive read locks into the dependency graph, we need to store the types of dependencies for the BFS later. There are four types of dependencies: * Exclusive -> Non-recursive dependencies: EN e.g. write_lock(prev) held and try to acquire write_lock(next) or non-recursive read_lock(next), which can be represented as "prev -(EN)-> next" * Shared -> Non-recursive dependencies: SN e.g. read_lock(prev) held and try to acquire write_lock(next) or non-recursive read_lock(next), which can be represented as "prev -(SN)-> next" * Exclusive -> Recursive dependencies: ER e.g. write_lock(prev) held and try to acquire recursive read_lock(next), which can be represented as "prev -(ER)-> next" * Shared -> Recursive dependencies: SR e.g. read_lock(prev) held and try to acquire recursive read_lock(next), which can be represented as "prev -(SR)-> next" So we use 4 bits for the presence of each type in lock_list::dep. Helper functions and macros are also introduced to convert a pair of locks into lock_list::dep bit and maintain the addition of different types of dependencies. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-7-boqun.feng@gmail.com
2020-08-26lockdep: Reduce the size of lock_list::distanceBoqun Feng1-3/+3
lock_list::distance is always not greater than MAX_LOCK_DEPTH (which is 48 right now), so a u16 will fit. This patch reduces the size of lock_list::distance to save space, so that we can introduce other fields to help detect recursive read lock deadlocks without increasing the size of lock_list structure. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-6-boqun.feng@gmail.com
2020-08-26lockdep: Make __bfs() visit every dependency until a matchBoqun Feng1-26/+35
Currently, __bfs() will do a breadth-first search in the dependency graph and visit each lock class in the graph exactly once, so for example, in the following graph: A ---------> B | ^ | | +----------> C a __bfs() call starts at A, will visit B through dependency A -> B and visit C through dependency A -> C and that's it, IOW, __bfs() will not visit dependency C -> B. This is OK for now, as we only have strong dependencies in the dependency graph, so whenever there is a traverse path from A to B in __bfs(), it means A has strong dependencies to B (IOW, B depends on A strongly). So no need to visit all dependencies in the graph. However, as we are going to add recursive-read lock into the dependency graph, as a result, not all the paths mean strong dependencies, in the same example above, dependency A -> B may be a weak dependency and traverse A -> C -> B may be a strong dependency path. And with the old way of __bfs() (i.e. visiting every lock class exactly once), we will miss the strong dependency path, which will result into failing to find a deadlock. To cure this for the future, we need to find a way for __bfs() to visit each dependency, rather than each class, exactly once in the search until we find a match. The solution is simple: We used to mark lock_class::lockdep_dependency_gen_id to indicate a class has been visited in __bfs(), now we change the semantics a little bit: we now mark lock_class::lockdep_dependency_gen_id to indicate _all the dependencies_ in its lock_{after,before} have been visited in the __bfs() (note we only take one direction in a __bfs() search). In this way, every dependency is guaranteed to be visited until we find a match. Note: the checks in mark_lock_accessed() and lock_accessed() are removed, because after this modification, we may call these two functions on @source_entry of __bfs(), which may not be the entry in "list_entries" Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-5-boqun.feng@gmail.com
2020-08-26lockdep: Demagic the return value of BFSBoqun Feng1-66/+89
__bfs() could return four magic numbers: 1: search succeeds, but none match. 0: search succeeds, find one match. -1: search fails because of the cq is full. -2: search fails because a invalid node is found. This patch cleans things up by using a enum type for the return value of __bfs() and its friends, this improves the code readability of the code, and further, could help if we want to extend the BFS. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-4-boqun.feng@gmail.com
2020-08-26locking: More accurate annotations for read_lock()Boqun Feng1-0/+14
On the archs using QUEUED_RWLOCKS, read_lock() is not always a recursive read lock, actually it's only recursive if in_interrupt() is true. So change the annotation accordingly to catch more deadlocks. Note we used to treat read_lock() as pure recursive read locks in lib/locking-seftest.c, and this is useful, especially for the lockdep development selftest, so we keep this via a variable to force switching lock annotation for read_lock(). Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-2-boqun.feng@gmail.com
2020-08-26lockdep,trace: Expose tracepointsPeter Zijlstra1-5/+9
The lockdep tracepoints are under the lockdep recursion counter, this has a bunch of nasty side effects: - TRACE_IRQFLAGS doesn't work across the entire tracepoint - RCU-lockdep doesn't see the tracepoints either, hiding numerous "suspicious RCU usage" warnings. Pull the trace_lock_*() tracepoints completely out from under the lockdep recursion handling and completely rely on the trace level recusion handling -- also, tracing *SHOULD* not be taking locks in any case. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Marco Elver <elver@google.com> Link: https://lkml.kernel.org/r/20200821085348.782688941@infradead.org
2020-08-26lockdep: Use raw_cpu_*() for per-cpu variablesPeter Zijlstra1-2/+2
Sven reported that commit a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") caused trouble on s390 because their this_cpu_*() primitives disable preemption which then lands back tracing. On the one hand, per-cpu ops should use preempt_*able_notrace() and raw_local_irq_*(), on the other hand, we can trivialy use raw_cpu_*() ops for this. Fixes: a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") Reported-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200821085348.192346882@infradead.org
2020-08-04Merge tag 'uninit-macro-v5.9-rc1' of ↵Linus Torvalds1-8/+8
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull uninitialized_var() macro removal from Kees Cook: "This is long overdue, and has hidden too many bugs over the years. The series has several "by hand" fixes, and then a trivial treewide replacement. - Clean up non-trivial uses of uninitialized_var() - Update documentation and checkpatch for uninitialized_var() removal - Treewide removal of uninitialized_var()" * tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: compiler: Remove uninitialized_var() macro treewide: Remove uninitialized_var() usage checkpatch: Remove awareness of uninitialized_var() macro mm/debug_vm_pgtable: Remove uninitialized_var() usage f2fs: Eliminate usage of uninitialized_var() macro media: sur40: Remove uninitialized_var() usage KVM: PPC: Book3S PR: Remove uninitialized_var() usage clk: spear: Remove uninitialized_var() usage clk: st: Remove uninitialized_var() usage spi: davinci: Remove uninitialized_var() usage ide: Remove uninitialized_var() usage rtlwifi: rtl8192cu: Remove uninitialized_var() usage b43: Remove uninitialized_var() usage drbd: Remove uninitialized_var() usage x86/mm/numa: Remove uninitialized_var() usage docs: deprecated.rst: Add uninitialized_var()
2020-08-03Merge tag 'locking-core-2020-08-03' of ↵Linus Torvalds1-48/+94
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - LKMM updates: mostly documentation changes, but also some new litmus tests for atomic ops. - KCSAN updates: the most important change is that GCC 11 now has all fixes in place to support KCSAN, so GCC support can be enabled again. Also more annotations. - futex updates: minor cleanups and simplifications - seqlock updates: merge preparatory changes/cleanups for the 'associated locks' facilities. - lockdep updates: - simplify IRQ trace event handling - add various new debug checks - simplify header dependencies, split out <linux/lockdep_types.h>, decouple lockdep from other low level headers some more - fix NMI handling - misc cleanups and smaller fixes * tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) kcsan: Improve IRQ state trace reporting lockdep: Refactor IRQ trace events fields into struct seqlock: lockdep assert non-preemptibility on seqcount_t write lockdep: Add preemption enabled/disabled assertion APIs seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount() seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs seqlock: Reorder seqcount_t and seqlock_t API definitions seqlock: seqcount_t latch: End read sections with read_seqcount_retry() seqlock: Properly format kernel-doc code samples Documentation: locking: Describe seqlock design and usage locking/qspinlock: Do not include atomic.h from qspinlock_types.h locking/atomic: Move ATOMIC_INIT into linux/types.h lockdep: Move list.h inclusion into lockdep.h locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs futex: Remove unused or redundant includes futex: Consistently use fshared as boolean futex: Remove needless goto's futex: Remove put_futex_key() rwsem: fix commas in initialisation docs: locking: Replace HTTP links with HTTPS ones ...
2020-08-03Merge branch 'locking/nmi' into locking/core, to pick up completed topic branchIngo Molnar1-1/+7
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-07-31lockdep: Refactor IRQ trace events fields into structMarco Elver1-28/+30
Refactor the IRQ trace events fields, used for printing information about the IRQ trace events, into a separate struct 'irqtrace_events'. This improves readability by separating the information only used in reporting, as well as enables (simplified) storing/restoring of irqtrace_events snapshots. No functional change intended. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200729110916.3920464-1-elver@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-07-27locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIspeterz@infradead.org1-1/+7
Prior to commit: 859d069ee1dd ("lockdep: Prepare for NMI IRQ state tracking") IRQ state tracking was disabled in NMIs due to nmi_enter() doing lockdep_off() -- with the obvious requirement that NMI entry call nmi_enter() before trace_hardirqs_off(). [ AFAICT, PowerPC and SH violate this order on their NMI entry ] However, that commit explicitly changed lockdep_hardirqs_*() to ignore lockdep_off() and breaks every architecture that has irq-tracing in it's NMI entry that hasn't been fixed up (x86 being the only fixed one at this point). The reason for this change is that by ignoring lockdep_off() we can: - get rid of 'current->lockdep_recursion' in lockdep_assert_irqs*() which was going to to give header-recursion issues with the seqlock rework. - allow these lockdep_assert_*() macros to function in NMI context. Restore the previous state of things and allow an architecture to opt-in to the NMI IRQ tracking support, however instead of relying on lockdep_off(), rely on in_nmi(), both are part of nmi_enter() and so over-all entry ordering doesn't need to change. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200727124852.GK119549@hirez.programming.kicks-ass.net
2020-07-16treewide: Remove uninitialized_var() usageKees Cook1-8/+8
Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>
2020-07-10lockdep: Remove lockdep_hardirq{s_enabled,_context}() argumentPeter Zijlstra1-15/+15
Now that the macros use per-cpu data, we no longer need the argument. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200623083721.571835311@infradead.org
2020-07-10lockdep: Change hardirq{s_enabled,_context} to per-cpu variablesPeter Zijlstra1-15/+15
Currently all IRQ-tracking state is in task_struct, this means that task_struct needs to be defined before we use it. Especially for lockdep_assert_irq*() this can lead to header-hell. Move the hardirq state into per-cpu variables to avoid the task_struct dependency. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200623083721.512673481@infradead.org
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