From 14819ea1e0bcbdc9b084cd60a6a24d5d786324ef Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 14 Jan 2009 12:34:21 +0100 Subject: irq: export __set_irq_handler() and handle_level_irq() Impact: build fix ARM updates broke x86 allmodconfig builds: ERROR: "__set_irq_handler" [drivers/mfd/pcf50633-core.ko] undefined! ERROR: "handle_level_irq" [drivers/mfd/pcf50633-core.ko] undefined! Signed-off-by: Ingo Molnar --- kernel/irq/chip.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index f63c706d25e1..7de11bd64dfe 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -383,6 +383,7 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc) out_unlock: spin_unlock(&desc->lock); } +EXPORT_SYMBOL_GPL(handle_level_irq); /** * handle_fasteoi_irq - irq handler for transparent controllers @@ -593,6 +594,7 @@ __set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained, } spin_unlock_irqrestore(&desc->lock, flags); } +EXPORT_SYMBOL_GPL(__set_irq_handler); void set_irq_chip_and_handler(unsigned int irq, struct irq_chip *chip, -- cgit v1.2.3 From 091d71e023557136e96f0e54f301497a3fc95dc3 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sat, 17 Jan 2009 00:10:45 +0100 Subject: PM: Fix compilation warning in kernel/power/main.c Reorder the code in kernel/power/main.c to fix compilation warning triggered by unsetting CONFIG_SUSPEND. Signed-off-by: Rafael J. Wysocki Signed-off-by: Len Brown --- kernel/power/main.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) (limited to 'kernel') diff --git a/kernel/power/main.c b/kernel/power/main.c index 239988873971..b4d219016b6c 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -57,16 +57,6 @@ int pm_notifier_call_chain(unsigned long val) #ifdef CONFIG_PM_DEBUG int pm_test_level = TEST_NONE; -static int suspend_test(int level) -{ - if (pm_test_level == level) { - printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n"); - mdelay(5000); - return 1; - } - return 0; -} - static const char * const pm_tests[__TEST_AFTER_LAST] = { [TEST_NONE] = "none", [TEST_CORE] = "core", @@ -125,14 +115,24 @@ static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr, } power_attr(pm_test); -#else /* !CONFIG_PM_DEBUG */ -static inline int suspend_test(int level) { return 0; } -#endif /* !CONFIG_PM_DEBUG */ +#endif /* CONFIG_PM_DEBUG */ #endif /* CONFIG_PM_SLEEP */ #ifdef CONFIG_SUSPEND +static int suspend_test(int level) +{ +#ifdef CONFIG_PM_DEBUG + if (pm_test_level == level) { + printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n"); + mdelay(5000); + return 1; + } +#endif /* !CONFIG_PM_DEBUG */ + return 0; +} + #ifdef CONFIG_PM_TEST_SUSPEND /* -- cgit v1.2.3 From f90d4118bacef87894621a3e8aba853fa0c89abc Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Fri, 16 Jan 2009 10:24:10 +0800 Subject: cpuset: fix possible deadlock in async_rebuild_sched_domains Lockdep reported some possible circular locking info when we tested cpuset on NUMA/fake NUMA box. ======================================================= [ INFO: possible circular locking dependency detected ] 2.6.29-rc1-00224-ga652504 #111 ------------------------------------------------------- bash/2968 is trying to acquire lock: (events){--..}, at: [] flush_work+0x24/0xd8 but task is already holding lock: (cgroup_mutex){--..}, at: [] cgroup_lock_live_group+0x12/0x29 which lock already depends on the new lock. ...... ------------------------------------------------------- Steps to reproduce: # mkdir /dev/cpuset # mount -t cpuset xxx /dev/cpuset # mkdir /dev/cpuset/0 # echo 0 > /dev/cpuset/0/cpus # echo 0 > /dev/cpuset/0/mems # echo 1 > /dev/cpuset/0/memory_migrate # cat /dev/zero > /dev/null & # echo $! > /dev/cpuset/0/tasks This is because async_rebuild_sched_domains has the following lock sequence: run_workqueue(async_rebuild_sched_domains) -> do_rebuild_sched_domains -> cgroup_lock But, attaching tasks when memory_migrate is set has following: cgroup_lock_live_group(cgroup_tasks_write) -> do_migrate_pages -> flush_work This patch fixes it by using a separate workqueue thread. Signed-off-by: Miao Xie Signed-off-by: Lai Jiangshan Signed-off-by: Ingo Molnar --- kernel/cpuset.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/cpuset.c b/kernel/cpuset.c index a85678865c5e..f76db9dcaa05 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -60,6 +60,14 @@ #include #include +/* + * Workqueue for cpuset related tasks. + * + * Using kevent workqueue may cause deadlock when memory_migrate + * is set. So we create a separate workqueue thread for cpuset. + */ +static struct workqueue_struct *cpuset_wq; + /* * Tracks how many cpusets are currently defined in system. * When there is only one cpuset (the root cpuset) we can @@ -831,7 +839,7 @@ static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains); */ static void async_rebuild_sched_domains(void) { - schedule_work(&rebuild_sched_domains_work); + queue_work(cpuset_wq, &rebuild_sched_domains_work); } /* @@ -2111,6 +2119,9 @@ void __init cpuset_init_smp(void) hotcpu_notifier(cpuset_track_online_cpus, 0); hotplug_memory_notifier(cpuset_track_online_nodes, 10); + + cpuset_wq = create_singlethread_workqueue("cpuset"); + BUG_ON(!cpuset_wq); } /** -- cgit v1.2.3 From 082605de5f82eb692cc90f7fda071cc01bb5ac34 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 19 Jan 2009 14:32:51 -0500 Subject: ring-buffer: fix alignment problem Impact: fix to allow some archs to use the ring buffer Commits in the ring buffer are checked by pointer arithmetic. If the calculation is incorrect, then the commits will never take place and the buffer will simply fill up and report an error. Each page in the ring buffer has a small header: struct buffer_data_page { u64 time_stamp; local_t commit; unsigned char data[]; }; Unfortuntely, some of the calculations used sizeof(struct buffer_data_page) to know the size of the header. But this is incorrect on some archs, where sizeof(struct buffer_data_page) does not equal offsetof(struct buffer_data_page, data), and on those archs, the commits are never processed. This patch replaces the sizeof with offsetof. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8b0daf0662ef..1d6526361d06 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -246,7 +246,7 @@ static inline int test_time_stamp(u64 delta) return 0; } -#define BUF_PAGE_SIZE (PAGE_SIZE - sizeof(struct buffer_data_page)) +#define BUF_PAGE_SIZE (PAGE_SIZE - offsetof(struct buffer_data_page, data)) /* * head_page == tail_page && head == tail then buffer is empty. -- cgit v1.2.3 From 00f57f545afa422db3003b0d0b30a30f8de7ecb2 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 14 Jan 2009 13:33:27 -0800 Subject: tracing/function-graph-tracer: fix a regression while suspend to disk Impact: fix a crash while kernel image restore When the function graph tracer is running and while suspend to disk, some racy and dangerous things happen against this tracer. The current task will save its registers including the stack pointer which contains the return address hooked by the tracer. But the current task will continue to enter other functions after that to save the memory, and then it will store other return addresses, and finally loose the old depth which matches the return address saved in the old stack (during the registers saving). So on image restore, the code will return to wrong addresses. And there are other things: on restore, the task will have it's "current" pointer overwritten during registers restoring....switching from one task to another... That would be insane to try to trace function graphs at these stages. This patch makes the function graph tracer listening on power events, making it's tracing disabled for the current task (the one that performs the hibernation work) while suspend/resume to disk, making the tracing safe during hibernation. Signed-off-by: Frederic Weisbecker Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ftrace.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 2f32969c09df..7dcf6e9f2b04 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -1965,6 +1966,7 @@ ftrace_enable_sysctl(struct ctl_table *table, int write, #ifdef CONFIG_FUNCTION_GRAPH_TRACER static atomic_t ftrace_graph_active; +static struct notifier_block ftrace_suspend_notifier; int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace) { @@ -2043,6 +2045,27 @@ static int start_graph_tracing(void) return ret; } +/* + * Hibernation protection. + * The state of the current task is too much unstable during + * suspend/restore to disk. We want to protect against that. + */ +static int +ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state, + void *unused) +{ + switch (state) { + case PM_HIBERNATION_PREPARE: + pause_graph_tracing(); + break; + + case PM_POST_HIBERNATION: + unpause_graph_tracing(); + break; + } + return NOTIFY_DONE; +} + int register_ftrace_graph(trace_func_graph_ret_t retfunc, trace_func_graph_ent_t entryfunc) { @@ -2050,6 +2073,9 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc, mutex_lock(&ftrace_sysctl_lock); + ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call; + register_pm_notifier(&ftrace_suspend_notifier); + atomic_inc(&ftrace_graph_active); ret = start_graph_tracing(); if (ret) { @@ -2075,6 +2101,7 @@ void unregister_ftrace_graph(void) ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub; ftrace_graph_entry = ftrace_graph_entry_stub; ftrace_shutdown(FTRACE_STOP_FUNC_RET); + unregister_pm_notifier(&ftrace_suspend_notifier); mutex_unlock(&ftrace_sysctl_lock); } -- cgit v1.2.3 From 551b4048b3d4acf15aff9fe4aed89b892c135b02 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Mon, 12 Jan 2009 11:06:18 +0800 Subject: ring_buffer: reset write when reserve buffer fail Impact: reset struct buffer_page.write when interrupt storm if struct buffer_page.write is not reset, any succedent committing will corrupted ring_buffer: static inline void rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) { ...... cpu_buffer->commit_page->commit = cpu_buffer->commit_page->write; ...... } when "if (RB_WARN_ON(cpu_buffer, next_page == reader_page))", ring_buffer is disabled, but some reserved buffers may haven't been committed. we need reset struct buffer_page.write. when "if (unlikely(next_page == cpu_buffer->commit_page))", ring_buffer is still available, we should not corrupt it. Signed-off-by: Lai Jiangshan Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 1d6526361d06..9c1e73da4e30 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1025,12 +1025,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, } if (next_page == head_page) { - if (!(buffer->flags & RB_FL_OVERWRITE)) { - /* reset write */ - if (tail <= BUF_PAGE_SIZE) - local_set(&tail_page->write, tail); + if (!(buffer->flags & RB_FL_OVERWRITE)) goto out_unlock; - } /* tail_page has not moved yet? */ if (tail_page == cpu_buffer->tail_page) { @@ -1105,6 +1101,10 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, return event; out_unlock: + /* reset write */ + if (tail <= BUF_PAGE_SIZE) + local_set(&tail_page->write, tail); + __raw_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); return NULL; -- cgit v1.2.3 From faf6861ebd776871e77b761c43ec045cd20b5716 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 14 Jan 2009 12:24:42 -0500 Subject: trace: print ftrace_dump at KERN_EMERG log level Impact: fix to print out ftrace_dump when expected I was debugging a hard race condition to only find out that after I hit the race, my log level was not at level to show KERN_INFO. The time it took to trigger the race was wasted because I did not capture the trace. Since ftrace_dump is only called from kernel oops (and only when it is set in the kernel command line to do so), or when a developer adds it to their own local tree, the log level of the print should be at KERN_EMERG to make sure the print appears. ftrace_dump is not called by a normal user setup, and will not add extra unwanted print out to the console. There is no reason it should be at KERN_INFO. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c580233add95..1a1c5a6ab24e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3736,7 +3736,7 @@ static struct notifier_block trace_die_notifier = { * it if we decide to change what log level the ftrace dump * should be at. */ -#define KERN_TRACE KERN_INFO +#define KERN_TRACE KERN_EMERG static void trace_printk_seq(struct trace_seq *s) -- cgit v1.2.3 From a442e5e0a2011af5b2d1f118fee0a8f9079f1d88 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 14 Jan 2009 14:50:19 -0500 Subject: trace: stop all recording to ring buffer on ftrace_dump Impact: limit ftrace dump output Currently ftrace_dump only calls ftrace_kill that is a fast way to prevent the function tracer functions from being called (just sets a flag and clears the function to call, nothing else). It is better to also turn off any recording to the ring buffers as well. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/trace.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 1a1c5a6ab24e..4d89e84f0f4b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3770,6 +3770,7 @@ void ftrace_dump(void) dump_ran = 1; /* No turning back! */ + tracing_off(); ftrace_kill(); for_each_tracing_cpu(cpu) { -- cgit v1.2.3 From 1092307d582a7566d23779c304cf86f3075ac5f0 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 15 Jan 2009 23:40:11 -0500 Subject: trace: set max latency variable to zero on default Impact: trace max latencies on start of latency tracing This patch sets the max latency to zero whenever one of the irq variant tracers or the wakeup tracer is set to current tracer. Most developers expect to see output when starting up a latency tracer. But since the max_latency is already set to max, and it takes a latency greater than max_latency to be recorded, there is no trace. This is not the expected behavior and has even confused myself. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/trace.c | 2 +- kernel/trace/trace_irqsoff.c | 1 + kernel/trace/trace_sched_wakeup.c | 1 + 3 files changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4d89e84f0f4b..17bb88d86ac2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -40,7 +40,7 @@ #define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE) -unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX; +unsigned long __read_mostly tracing_max_latency; unsigned long __read_mostly tracing_thresh; /* diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 7c2e326bbc8b..62a78d943534 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -380,6 +380,7 @@ static void stop_irqsoff_tracer(struct trace_array *tr) static void __irqsoff_tracer_init(struct trace_array *tr) { + tracing_max_latency = 0; irqsoff_trace = tr; /* make sure that the tracer is visible */ smp_wmb(); diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 43586b689e31..42ae1e77b6b3 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -333,6 +333,7 @@ static void stop_wakeup_tracer(struct trace_array *tr) static int wakeup_tracer_init(struct trace_array *tr) { + tracing_max_latency = 0; wakeup_trace = tr; start_wakeup_tracer(tr); return 0; -- cgit v1.2.3 From 91a8d07d82cac3aae3ef2ea1aaba5c9c4a934e91 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 21 Jan 2009 18:45:57 -0500 Subject: ring-buffer: reset timestamps when ring buffer is reset Impact: fix bad times of recent resets The ring buffer needs to reset its timestamps when reseting of the buffer, otherwise the timestamps are stale and might be used to calculate times in the buffer causing funny timestamps to appear. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 9c1e73da4e30..bd38c5cfd8ad 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2174,6 +2174,9 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->overrun = 0; cpu_buffer->entries = 0; + + cpu_buffer->write_stamp = 0; + cpu_buffer->read_stamp = 0; } /** -- cgit v1.2.3 From 3a9f84d354ce1e19956083c8e691727dea33bd5a Mon Sep 17 00:00:00 2001 From: Ed Swierk Date: Mon, 26 Jan 2009 15:33:31 -0800 Subject: signals, debug: fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal() With print-fatal-signals=1 on a kernel with CONFIG_PREEMPT=y, sending an unexpected signal to a process causes a BUG: using smp_processor_id() in preemptible code. get_signal_to_deliver() releases the siglock before calling print_fatal_signal(), which calls show_regs(), which calls smp_processor_id(), which is not supposed to be called from a preemptible thread. Make sure show_regs() runs with preemption disabled. Signed-off-by: Ed Swierk Signed-off-by: Ingo Molnar --- kernel/signal.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/signal.c b/kernel/signal.c index e73759783dc8..b6b36768b758 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -909,7 +909,9 @@ static void print_fatal_signal(struct pt_regs *regs, int signr) } #endif printk("\n"); + preempt_disable(); show_regs(regs); + preempt_enable(); } static int __init setup_print_fatal_signals(char *str) -- cgit v1.2.3 From d7240b988017521ebf89edfadd42c0942f166850 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 29 Jan 2009 10:08:01 -0500 Subject: generic-ipi: use per cpu data for single cpu ipi calls The smp_call_function can be passed a wait parameter telling it to wait for all the functions running on other CPUs to complete before returning, or to return without waiting. Unfortunately, this is currently just a suggestion and not manditory. That is, the smp_call_function can decide not to return and wait instead. The reason for this is because it uses kmalloc to allocate storage to send to the called CPU and that CPU will free it when it is done. But if we fail to allocate the storage, the stack is used instead. This means we must wait for the called CPU to finish before continuing. Unfortunatly, some callers do no abide by this hint and act as if the non-wait option is mandatory. The MTRR code for instance will deadlock if the smp_call_function is set to wait. This is because the smp_call_function will wait for the other CPUs to finish their called functions, but those functions are waiting on the caller to continue. This patch changes the generic smp_call_function code to use per cpu variables if the allocation of the data fails for a single CPU call. The smp_call_function_many will fall back to the smp_call_function_single if it fails its alloc. The smp_call_function_single is modified to not force the wait state. Since we now are using a single data per cpu we must synchronize the callers to prevent a second caller modifying the data before the first called IPI functions complete. To do so, I added a flag to the call_single_data called CSD_FLAG_LOCK. When the single CPU is called (which can be called when a many call fails an alloc), we set the LOCK bit on this per cpu data. When the caller finishes it clears the LOCK bit. The caller must wait till the LOCK bit is cleared before setting it. When it is cleared, there is no IPI function using it. Signed-off-by: Steven Rostedt Signed-off-by: Peter Zijlstra Acked-by: Jens Axboe Acked-by: Linus Torvalds Signed-off-by: Ingo Molnar --- kernel/smp.c | 36 +++++++++++++++++++++++++++++++++--- 1 file changed, 33 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/smp.c b/kernel/smp.c index 5cfa0e5e3e88..bbedbb7efe32 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -18,6 +18,7 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock); enum { CSD_FLAG_WAIT = 0x01, CSD_FLAG_ALLOC = 0x02, + CSD_FLAG_LOCK = 0x04, }; struct call_function_data { @@ -186,6 +187,9 @@ void generic_smp_call_function_single_interrupt(void) if (data_flags & CSD_FLAG_WAIT) { smp_wmb(); data->flags &= ~CSD_FLAG_WAIT; + } else if (data_flags & CSD_FLAG_LOCK) { + smp_wmb(); + data->flags &= ~CSD_FLAG_LOCK; } else if (data_flags & CSD_FLAG_ALLOC) kfree(data); } @@ -196,6 +200,8 @@ void generic_smp_call_function_single_interrupt(void) } } +static DEFINE_PER_CPU(struct call_single_data, csd_data); + /* * smp_call_function_single - Run a function on a specific CPU * @func: The function to run. This must be fast and non-blocking. @@ -224,14 +230,38 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, func(info); local_irq_restore(flags); } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { - struct call_single_data *data = NULL; + struct call_single_data *data; if (!wait) { + /* + * We are calling a function on a single CPU + * and we are not going to wait for it to finish. + * We first try to allocate the data, but if we + * fail, we fall back to use a per cpu data to pass + * the information to that CPU. Since all callers + * of this code will use the same data, we must + * synchronize the callers to prevent a new caller + * from corrupting the data before the callee + * can access it. + * + * The CSD_FLAG_LOCK is used to let us know when + * the IPI handler is done with the data. + * The first caller will set it, and the callee + * will clear it. The next caller must wait for + * it to clear before we set it again. This + * will make sure the callee is done with the + * data before a new caller will use it. + */ data = kmalloc(sizeof(*data), GFP_ATOMIC); if (data) data->flags = CSD_FLAG_ALLOC; - } - if (!data) { + else { + data = &per_cpu(csd_data, me); + while (data->flags & CSD_FLAG_LOCK) + cpu_relax(); + data->flags = CSD_FLAG_LOCK; + } + } else { data = &d; data->flags = CSD_FLAG_WAIT; } -- cgit v1.2.3 From 7f22391cbe82a80a9f891d8bd10fc28ff248d1e2 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 22 Dec 2008 02:24:48 +0100 Subject: hrtimers: increase clock min delta threshold while interrupt hanging Impact: avoid timer IRQ hanging slow systems While using the function graph tracer on a virtualized system, the hrtimer_interrupt can hang the system on an infinite loop. This can be caused in several situations: - the hardware is very slow and HZ is set too high - something intrusive is slowing the system down (tracing under emulation) ... and the next clock events to program are always before the current time. This patch implements a reasonable compromise: if such a situation is detected, we share the CPUs time in 1/4 to process the hrtimer interrupts. This is enough to let the system running without serious starvation. It has been successfully tested under VirtualBox with 1000 HZ and 100 HZ with function graph tracer launched. On both cases, the clock events were increased until about 25 ms periodic ticks, which means 40 HZ. So we change a hard to debug hang into a warning message and a system that still manages to limp along. Signed-off-by: Frederic Weisbecker Signed-off-by: Ingo Molnar --- kernel/hrtimer.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index f33afb0407bc..8fea312ca36c 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1158,6 +1158,29 @@ static void __run_hrtimer(struct hrtimer *timer) #ifdef CONFIG_HIGH_RES_TIMERS +static int force_clock_reprogram; + +/* + * After 5 iteration's attempts, we consider that hrtimer_interrupt() + * is hanging, which could happen with something that slows the interrupt + * such as the tracing. Then we force the clock reprogramming for each future + * hrtimer interrupts to avoid infinite loops and use the min_delta_ns + * threshold that we will overwrite. + * The next tick event will be scheduled to 3 times we currently spend on + * hrtimer_interrupt(). This gives a good compromise, the cpus will spend + * 1/4 of their time to process the hrtimer interrupts. This is enough to + * let it running without serious starvation. + */ + +static inline void +hrtimer_interrupt_hanging(struct clock_event_device *dev, + ktime_t try_time) +{ + force_clock_reprogram = 1; + dev->min_delta_ns = (unsigned long)try_time.tv64 * 3; + printk(KERN_WARNING "hrtimer: interrupt too slow, " + "forcing clock min delta to %lu ns\n", dev->min_delta_ns); +} /* * High resolution timer interrupt * Called with interrupts disabled @@ -1167,6 +1190,7 @@ void hrtimer_interrupt(struct clock_event_device *dev) struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); struct hrtimer_clock_base *base; ktime_t expires_next, now; + int nr_retries = 0; int i; BUG_ON(!cpu_base->hres_active); @@ -1174,6 +1198,10 @@ void hrtimer_interrupt(struct clock_event_device *dev) dev->next_event.tv64 = KTIME_MAX; retry: + /* 5 retries is enough to notice a hang */ + if (!(++nr_retries % 5)) + hrtimer_interrupt_hanging(dev, ktime_sub(ktime_get(), now)); + now = ktime_get(); expires_next.tv64 = KTIME_MAX; @@ -1226,7 +1254,7 @@ void hrtimer_interrupt(struct clock_event_device *dev) /* Reprogramming necessary ? */ if (expires_next.tv64 != KTIME_MAX) { - if (tick_program_event(expires_next, 0)) + if (tick_program_event(expires_next, force_clock_reprogram)) goto retry; } } -- cgit v1.2.3 From 94df7de0289bc2df3d6e85cd2ece52bf42682f45 Mon Sep 17 00:00:00 2001 From: Sebastien Dugue Date: Mon, 1 Dec 2008 14:09:07 +0100 Subject: hrtimers: allow the hot-unplugging of all cpus Impact: fix CPU hotplug hang on Power6 testbox On architectures that support offlining all cpus (at least powerpc/pseries), hot-unpluging the tick_do_timer_cpu can result in a system hang. This comes from the fact that if the cpu going down happens to be the cpu doing the tick, then as the tick_do_timer_cpu handover happens after the cpu is dead (via the CPU_DEAD notification), we're left without ticks, jiffies are frozen and any task relying on timers (msleep, ...) is stuck. That's particularly the case for the cpu looping in __cpu_die() waiting for the dying cpu to be dead. This patch addresses this by having the tick_do_timer_cpu handover happen earlier during the CPU_DYING notification. For this, a new clockevent notification type is introduced (CLOCK_EVT_NOTIFY_CPU_DYING) which is triggered in hrtimer_cpu_notify(). Signed-off-by: Sebastien Dugue Cc: Signed-off-by: Ingo Molnar --- include/linux/clockchips.h | 1 + kernel/hrtimer.c | 4 ++++ kernel/time/tick-common.c | 26 +++++++++++++++++++------- 3 files changed, 24 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h index cea153697ec7..3a1dbba4d3ae 100644 --- a/include/linux/clockchips.h +++ b/include/linux/clockchips.h @@ -36,6 +36,7 @@ enum clock_event_nofitiers { CLOCK_EVT_NOTIFY_BROADCAST_EXIT, CLOCK_EVT_NOTIFY_SUSPEND, CLOCK_EVT_NOTIFY_RESUME, + CLOCK_EVT_NOTIFY_CPU_DYING, CLOCK_EVT_NOTIFY_CPU_DEAD, }; diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 8fea312ca36c..647a40e2fea1 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1608,6 +1608,10 @@ static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self, break; #ifdef CONFIG_HOTPLUG_CPU + case CPU_DYING: + case CPU_DYING_FROZEN: + clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu); + break; case CPU_DEAD: case CPU_DEAD_FROZEN: { diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index 63e05d423a09..21a5ca849514 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -273,6 +273,21 @@ out_bc: return ret; } +/* + * Transfer the do_timer job away from a dying cpu. + * + * Called with interrupts disabled. + */ +static void tick_handover_do_timer(int *cpup) +{ + if (*cpup == tick_do_timer_cpu) { + int cpu = cpumask_first(cpu_online_mask); + + tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu : + TICK_DO_TIMER_NONE; + } +} + /* * Shutdown an event device on a given cpu: * @@ -297,13 +312,6 @@ static void tick_shutdown(unsigned int *cpup) clockevents_exchange_device(dev, NULL); td->evtdev = NULL; } - /* Transfer the do_timer job away from this cpu */ - if (*cpup == tick_do_timer_cpu) { - int cpu = cpumask_first(cpu_online_mask); - - tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu : - TICK_DO_TIMER_NONE; - } spin_unlock_irqrestore(&tick_device_lock, flags); } @@ -357,6 +365,10 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason, tick_broadcast_oneshot_control(reason); break; + case CLOCK_EVT_NOTIFY_CPU_DYING: + tick_handover_do_timer(dev); + break; + case CLOCK_EVT_NOTIFY_CPU_DEAD: tick_shutdown_broadcast_oneshot(dev); tick_shutdown_broadcast(dev); -- cgit v1.2.3 From b0a9b5111abf60ef07eade834f480e89004c7920 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 25 Jan 2009 11:31:36 +0100 Subject: hrtimer: prevent negative expiry value after clock_was_set() Impact: prevent false positive WARN_ON() in clockevents_program_event() clock_was_set() changes the base->offset of CLOCK_REALTIME and enforces the reprogramming of the clockevent device to expire timers which are based on CLOCK_REALTIME. If the clock change is large enough then the subtraction of the timer expiry value and base->offset can become negative which triggers the warning in clockevents_program_event(). Check the subtraction result and set a negative value to 0. Signed-off-by: Thomas Gleixner --- kernel/hrtimer.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 647a40e2fea1..f394d2a42ca3 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -501,6 +501,13 @@ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) continue; timer = rb_entry(base->first, struct hrtimer, node); expires = ktime_sub(hrtimer_get_expires(timer), base->offset); + /* + * clock_was_set() has changed base->offset so the + * result might be negative. Fix it up to prevent a + * false positive in clockevents_program_event() + */ + if (expires.tv64 < 0) + expires.tv64 = 0; if (expires.tv64 < cpu_base->expires_next.tv64) cpu_base->expires_next = expires; } -- cgit v1.2.3 From d942fb6c7d391baba3dddb566eb735fbf3df8528 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 26 Jan 2009 17:56:17 +0100 Subject: sched: fix sync wakeups Pawel Dziekonski reported that the openssl benchmark and his quantum chemistry application both show slowdowns due to the scheduler under-parallelizing execution. The reason are pipe wakeups still doing 'sync' wakeups which overrides the normal buddy wakeup logic - even if waker and wakee are loosely coupled. Fix an inversion of logic in the buddy wakeup code. Reported-by: Pawel Dziekonski Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/sched.c | 4 ++++ kernel/sched_fair.c | 11 ++--------- 2 files changed, 6 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/sched.c b/kernel/sched.c index 52bbf1c842a8..770b1f9ebe14 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2266,6 +2266,10 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) if (!sched_feat(SYNC_WAKEUPS)) sync = 0; + if (!sync && (current->se.avg_overlap < sysctl_sched_migration_cost && + p->se.avg_overlap < sysctl_sched_migration_cost)) + sync = 1; + #ifdef CONFIG_SMP if (sched_feat(LB_WAKEUP_UPDATE)) { struct sched_domain *sd; diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 5cc1c162044f..fdc417504681 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1179,20 +1179,15 @@ wake_affine(struct sched_domain *this_sd, struct rq *this_rq, int idx, unsigned long load, unsigned long this_load, unsigned int imbalance) { - struct task_struct *curr = this_rq->curr; - struct task_group *tg; unsigned long tl = this_load; unsigned long tl_per_task; + struct task_group *tg; unsigned long weight; int balanced; if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS)) return 0; - if (sync && (curr->se.avg_overlap > sysctl_sched_migration_cost || - p->se.avg_overlap > sysctl_sched_migration_cost)) - sync = 0; - /* * If sync wakeup then subtract the (maximum possible) * effect of the currently running task from the load @@ -1419,9 +1414,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync) if (!sched_feat(WAKEUP_PREEMPT)) return; - if (sched_feat(WAKEUP_OVERLAP) && (sync || - (se->avg_overlap < sysctl_sched_migration_cost && - pse->avg_overlap < sysctl_sched_migration_cost))) { + if (sched_feat(WAKEUP_OVERLAP) && sync) { resched_task(curr); return; } -- cgit v1.2.3 From 1596e29773eadd96b0a5fc6e736afa52394cafda Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 28 Jan 2009 14:51:38 +0100 Subject: sched: symmetric sync vs avg_overlap Reinstate the weakening of the sync hint if set. This yields a more symmetric usage of avg_overlap. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/sched.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/sched.c b/kernel/sched.c index 770b1f9ebe14..242d0d47a70d 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2266,9 +2266,15 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) if (!sched_feat(SYNC_WAKEUPS)) sync = 0; - if (!sync && (current->se.avg_overlap < sysctl_sched_migration_cost && - p->se.avg_overlap < sysctl_sched_migration_cost)) - sync = 1; + if (!sync) { + if (current->se.avg_overlap < sysctl_sched_migration_cost && + p->se.avg_overlap < sysctl_sched_migration_cost) + sync = 1; + } else { + if (current->se.avg_overlap >= sysctl_sched_migration_cost || + p->se.avg_overlap >= sysctl_sched_migration_cost) + sync = 0; + } #ifdef CONFIG_SMP if (sched_feat(LB_WAKEUP_UPDATE)) { -- cgit v1.2.3 From a9f3e2b549f83a9cdab873abf4140be27c05a3f2 Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Wed, 28 Jan 2009 14:51:39 +0100 Subject: sched: clear buddies more aggressively It was noticed that a task could get re-elected past its run quota due to buddy affinities. This could increase latency a little. Cure it by more aggresively clearing buddy state. We do so in two situations: - when we force preempt - when we select a buddy to run Signed-off-by: Mike Galbraith Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index fdc417504681..75248b9ff4c1 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -768,8 +768,14 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) ideal_runtime = sched_slice(cfs_rq, curr); delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; - if (delta_exec > ideal_runtime) + if (delta_exec > ideal_runtime) { resched_task(rq_of(cfs_rq)->curr); + /* + * The current task ran long enough, ensure it doesn't get + * re-elected due to buddy favours. + */ + clear_buddies(cfs_rq, curr); + } } static void @@ -1445,6 +1451,11 @@ static struct task_struct *pick_next_task_fair(struct rq *rq) do { se = pick_next_entity(cfs_rq); + /* + * If se was a buddy, clear it so that it will have to earn + * the favour again. + */ + clear_buddies(cfs_rq, se); set_next_entity(cfs_rq, se); cfs_rq = group_cfs_rq(se); } while (cfs_rq); -- cgit v1.2.3 From a571bbeafbcc501d9989fbce1cddcd810bd51d71 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 28 Jan 2009 14:51:40 +0100 Subject: sched: fix buddie group latency Similar to the previous patch, by not clearing buddies we can select entities past their run quota, which can increase latency. This means we have to clear group buddies as well. Do not use the group clear for pick_next_task(), otherwise that'll get O(n^2). Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 75248b9ff4c1..a7e50ba185ac 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -719,7 +719,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup) __enqueue_entity(cfs_rq, se); } -static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) +static void __clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) { if (cfs_rq->last == se) cfs_rq->last = NULL; @@ -728,6 +728,12 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) cfs_rq->next = NULL; } +static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) +{ + for_each_sched_entity(se) + __clear_buddies(cfs_rq_of(se), se); +} + static void dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep) { @@ -1455,7 +1461,7 @@ static struct task_struct *pick_next_task_fair(struct rq *rq) * If se was a buddy, clear it so that it will have to earn * the favour again. */ - clear_buddies(cfs_rq, se); + __clear_buddies(cfs_rq, se); set_next_entity(cfs_rq, se); cfs_rq = group_cfs_rq(se); } while (cfs_rq); -- cgit v1.2.3 From 3d398703ef06fd97b4c28c86b580546d5b57e7b7 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Sat, 31 Jan 2009 23:21:24 +1030 Subject: sched_rt: don't use first_cpu on cpumask created with cpumask_and cpumask_and() only initializes nr_cpu_ids bits, so the (deprecated) first_cpu() might find one of those uninitialized bits if nr_cpu_ids is less than NR_CPUS (as it can be for CONFIG_CPUMASK_OFFSTACK). Signed-off-by: Rusty Russell Signed-off-by: Ingo Molnar --- kernel/sched_rt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index 954e1a81b796..bac1061cea2f 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -968,8 +968,8 @@ static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask) if ((this_cpu != -1) && cpu_isset(this_cpu, *mask)) return this_cpu; - first = first_cpu(*mask); - if (first != NR_CPUS) + first = cpumask_first(mask); + if (first < nr_cpu_ids) return first; return -1; -- cgit v1.2.3 From 10b888d6cec2688e65e9e128b14bf98ecd199da2 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Sat, 31 Jan 2009 14:50:07 -0800 Subject: irq, x86: fix lock status with numa_migrate_irq_desc Eric Paris reported: > I have an hp dl785g5 which is unable to successfully run > 2.6.29-0.66.rc3.fc11.x86_64 or 2.6.29-rc2-next-20090126. During bootup > (early in userspace daemons starting) I get the below BUG, which quickly > renders the machine dead. I assume it is because sparse_irq_lock never > gets released when the BUG kills that task. Adjust lock sequence when migrating a descriptor with CONFIG_NUMA_MIGRATE_IRQ_DESC enabled. Signed-off-by: Yinghai Lu Signed-off-by: Ingo Molnar --- arch/x86/kernel/io_apic.c | 5 +++-- kernel/irq/numa_migrate.c | 7 ++++++- 2 files changed, 9 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c index 1c4a1302536c..9b0c480c383b 100644 --- a/arch/x86/kernel/io_apic.c +++ b/arch/x86/kernel/io_apic.c @@ -2528,14 +2528,15 @@ static void irq_complete_move(struct irq_desc **descp) vector = ~get_irq_regs()->orig_ax; me = smp_processor_id(); + + if (vector == cfg->vector && cpumask_test_cpu(me, cfg->domain)) { #ifdef CONFIG_NUMA_MIGRATE_IRQ_DESC *descp = desc = move_irq_desc(desc, me); /* get the new one */ cfg = desc->chip_data; #endif - - if (vector == cfg->vector && cpumask_test_cpu(me, cfg->domain)) send_cleanup_vector(cfg); + } } #else static inline void irq_complete_move(struct irq_desc **descp) {} diff --git a/kernel/irq/numa_migrate.c b/kernel/irq/numa_migrate.c index ecf765c6a77a..acd88356ac76 100644 --- a/kernel/irq/numa_migrate.c +++ b/kernel/irq/numa_migrate.c @@ -71,7 +71,7 @@ static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc, desc = irq_desc_ptrs[irq]; if (desc && old_desc != desc) - goto out_unlock; + goto out_unlock; node = cpu_to_node(cpu); desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node); @@ -84,10 +84,15 @@ static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc, init_copy_one_irq_desc(irq, old_desc, desc, cpu); irq_desc_ptrs[irq] = desc; + spin_unlock_irqrestore(&sparse_irq_lock, flags); /* free the old one */ free_one_irq_desc(old_desc, desc); + spin_unlock(&old_desc->lock); kfree(old_desc); + spin_lock(&desc->lock); + + return desc; out_unlock: spin_unlock_irqrestore(&sparse_irq_lock, flags); -- cgit v1.2.3 From 720eba31f47aeade8ec130ca7f4353223c49170f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 3 Feb 2009 13:31:36 +1030 Subject: modules: Use a better scheme for refcounting Current refcounting for modules (done if CONFIG_MODULE_UNLOAD=y) is using a lot of memory. Each 'struct module' contains an [NR_CPUS] array of full cache lines. This patch uses existing infrastructure (percpu_modalloc() & percpu_modfree()) to allocate percpu space for the refcount storage. Instead of wasting NR_CPUS*128 bytes (on i386), we now use nr_cpu_ids*sizeof(local_t) bytes. On a typical distro, where NR_CPUS=8, shiping 2000 modules, we reduce size of module files by about 2 Mbytes. (1Kb per module) Instead of having all refcounters in the same memory node - with TLB misses because of vmalloc() - this new implementation permits to have better NUMA properties, since each CPU will use storage on its preferred node, thanks to percpu storage. Signed-off-by: Eric Dumazet Signed-off-by: Rusty Russell Signed-off-by: Linus Torvalds --- include/linux/module.h | 25 ++++++++++++++++--------- kernel/module.c | 35 +++++++++++++++++++++++++---------- 2 files changed, 41 insertions(+), 19 deletions(-) (limited to 'kernel') diff --git a/include/linux/module.h b/include/linux/module.h index 4f7ea12463d3..f3b8329eb5b8 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -219,11 +219,6 @@ void *__symbol_get_gpl(const char *symbol); #endif -struct module_ref -{ - local_t count; -} ____cacheline_aligned; - enum module_state { MODULE_STATE_LIVE, @@ -344,8 +339,11 @@ struct module /* Destruction function. */ void (*exit)(void); - /* Reference counts */ - struct module_ref ref[NR_CPUS]; +#ifdef CONFIG_SMP + char *refptr; +#else + local_t ref; +#endif #endif }; #ifndef MODULE_ARCH_INIT @@ -395,13 +393,22 @@ void __symbol_put(const char *symbol); #define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x) void symbol_put_addr(void *addr); +static inline local_t *__module_ref_addr(struct module *mod, int cpu) +{ +#ifdef CONFIG_SMP + return (local_t *) (mod->refptr + per_cpu_offset(cpu)); +#else + return &mod->ref; +#endif +} + /* Sometimes we know we already have a refcount, and it's easier not to handle the error case (which only happens with rmmod --wait). */ static inline void __module_get(struct module *module) { if (module) { BUG_ON(module_refcount(module) == 0); - local_inc(&module->ref[get_cpu()].count); + local_inc(__module_ref_addr(module, get_cpu())); put_cpu(); } } @@ -413,7 +420,7 @@ static inline int try_module_get(struct module *module) if (module) { unsigned int cpu = get_cpu(); if (likely(module_is_live(module))) - local_inc(&module->ref[cpu].count); + local_inc(__module_ref_addr(module, cpu)); else ret = 0; put_cpu(); diff --git a/kernel/module.c b/kernel/module.c index e8b51d41dd72..ba22484a987e 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -573,13 +573,13 @@ static char last_unloaded_module[MODULE_NAME_LEN+1]; /* Init the unload section of the module. */ static void module_unload_init(struct module *mod) { - unsigned int i; + int cpu; INIT_LIST_HEAD(&mod->modules_which_use_me); - for (i = 0; i < NR_CPUS; i++) - local_set(&mod->ref[i].count, 0); + for_each_possible_cpu(cpu) + local_set(__module_ref_addr(mod, cpu), 0); /* Hold reference count during initialization. */ - local_set(&mod->ref[raw_smp_processor_id()].count, 1); + local_set(__module_ref_addr(mod, raw_smp_processor_id()), 1); /* Backwards compatibility macros put refcount during init. */ mod->waiter = current; } @@ -717,10 +717,11 @@ static int try_stop_module(struct module *mod, int flags, int *forced) unsigned int module_refcount(struct module *mod) { - unsigned int i, total = 0; + unsigned int total = 0; + int cpu; - for (i = 0; i < NR_CPUS; i++) - total += local_read(&mod->ref[i].count); + for_each_possible_cpu(cpu) + total += local_read(__module_ref_addr(mod, cpu)); return total; } EXPORT_SYMBOL(module_refcount); @@ -894,7 +895,7 @@ void module_put(struct module *module) { if (module) { unsigned int cpu = get_cpu(); - local_dec(&module->ref[cpu].count); + local_dec(__module_ref_addr(module, cpu)); /* Maybe they're waiting for us to drop reference? */ if (unlikely(!module_is_live(module))) wake_up_process(module->waiter); @@ -1464,7 +1465,10 @@ static void free_module(struct module *mod) kfree(mod->args); if (mod->percpu) percpu_modfree(mod->percpu); - +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + if (mod->refptr) + percpu_modfree(mod->refptr); +#endif /* Free lock-classes: */ lockdep_free_key_range(mod->module_core, mod->core_size); @@ -2011,6 +2015,14 @@ static noinline struct module *load_module(void __user *umod, if (err < 0) goto free_mod; +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t), + mod->name); + if (!mod->refptr) { + err = -ENOMEM; + goto free_mod; + } +#endif if (pcpuindex) { /* We have a special allocation for this section. */ percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size, @@ -2018,7 +2030,7 @@ static noinline struct module *load_module(void __user *umod, mod->name); if (!percpu) { err = -ENOMEM; - goto free_mod; + goto free_percpu; } sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC; mod->percpu = percpu; @@ -2282,6 +2294,9 @@ static noinline struct module *load_module(void __user *umod, free_percpu: if (percpu) percpu_modfree(percpu); +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + percpu_modfree(mod->refptr); +#endif free_mod: kfree(args); free_hdr: -- cgit v1.2.3 From 229c4ef8ae56d69f8dec64533bf1c7f8070c1a4a Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 3 Feb 2009 20:39:04 +0100 Subject: ftrace: do_each_pid_task() needs rcu lock "ftrace: use struct pid" commit 978f3a45d9499c7a447ca7615455cefb63d44165 converted ftrace_pid_trace to "struct pid*". But we can't use do_each_pid_task() without rcu_read_lock() even if we know the pid itself can't go away (it was pinned in ftrace_pid_write). The exiting task can detach itself from this pid at any moment. Signed-off-by: Oleg Nesterov Signed-off-by: Ingo Molnar --- kernel/trace/ftrace.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7dcf6e9f2b04..9a236ffe2aa4 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1737,9 +1737,12 @@ static void clear_ftrace_pid(struct pid *pid) { struct task_struct *p; + rcu_read_lock(); do_each_pid_task(pid, PIDTYPE_PID, p) { clear_tsk_trace_trace(p); } while_each_pid_task(pid, PIDTYPE_PID, p); + rcu_read_unlock(); + put_pid(pid); } @@ -1747,9 +1750,11 @@ static void set_ftrace_pid(struct pid *pid) { struct task_struct *p; + rcu_read_lock(); do_each_pid_task(pid, PIDTYPE_PID, p) { set_tsk_trace_trace(p); } while_each_pid_task(pid, PIDTYPE_PID, p); + rcu_read_unlock(); } static void clear_ftrace_pid_task(struct pid **pid) -- cgit v1.2.3 From 58763a297405024d23d8f1d0bba3e6603660c4b6 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 4 Feb 2009 15:11:58 -0800 Subject: kernel/async.c: fix printk warnings alpha: kernel/async.c: In function 'run_one_entry': kernel/async.c:141: warning: format '%lli' expects type 'long long int', but argument 2 has type 'async_cookie_t' kernel/async.c:149: warning: format '%lli' expects type 'long long int', but argument 2 has type 'async_cookie_t' kernel/async.c:149: warning: format '%lld' expects type 'long long int', but argument 4 has type 's64' kernel/async.c: In function 'async_synchronize_cookie_special': kernel/async.c:250: warning: format '%lli' expects type 'long long int', but argument 3 has type 's64' Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/async.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/async.c b/kernel/async.c index 608b32b42812..67a2be71f517 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -138,15 +138,18 @@ static void run_one_entry(void) /* 3) run it (and print duration)*/ if (initcall_debug && system_state == SYSTEM_BOOTING) { - printk("calling %lli_%pF @ %i\n", entry->cookie, entry->func, task_pid_nr(current)); + printk("calling %lli_%pF @ %i\n", (long long)entry->cookie, + entry->func, task_pid_nr(current)); calltime = ktime_get(); } entry->func(entry->data, entry->cookie); if (initcall_debug && system_state == SYSTEM_BOOTING) { rettime = ktime_get(); delta = ktime_sub(rettime, calltime); - printk("initcall %lli_%pF returned 0 after %lld usecs\n", entry->cookie, - entry->func, ktime_to_ns(delta) >> 10); + printk("initcall %lli_%pF returned 0 after %lld usecs\n", + (long long)entry->cookie, + entry->func, + (long long)ktime_to_ns(delta) >> 10); } /* 4) remove it from the running queue */ @@ -247,7 +250,8 @@ void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *r delta = ktime_sub(endtime, starttime); printk("async_continuing @ %i after %lli usec\n", - task_pid_nr(current), ktime_to_ns(delta) >> 10); + task_pid_nr(current), + (long long)ktime_to_ns(delta) >> 10); } } EXPORT_SYMBOL_GPL(async_synchronize_cookie_special); -- cgit v1.2.3 From 60fd760fb9ff7034360bab7137c917c0330628c2 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 4 Feb 2009 15:12:06 -0800 Subject: revert "rlimit: permit setting RLIMIT_NOFILE to RLIM_INFINITY" Revert commit 0c2d64fb6cae9aae480f6a46cfe79f8d7d48b59f because it causes (arguably poorly designed) existing userspace to spend interminable periods closing billions of not-open file descriptors. We could bring this back, with some sort of opt-in tunable in /proc, which defaults to "off". Peter's alanysis follows: : I spent several hours trying to get to the bottom of a serious : performance issue that appeared on one of our servers after upgrading to : 2.6.28. In the end it's what could be considered a userspace bug that : was triggered by a change in 2.6.28. Since this might also affect other : people I figured I'd at least document what I found here, and maybe we : can even do something about it: : : : So, I upgraded some of debian.org's machines to 2.6.28.1 and immediately : the team maintaining our ftp archive complained that one of their : scripts that previously ran in a few minutes still hadn't even come : close to being done after an hour or so. Downgrading to 2.6.27 fixed : that. : : Turns out that script is forking a lot and something in it or python or : whereever closes all the file descriptors it doesn't want to pass on. : That is, it starts at zero and goes up to ulimit -n/RLIMIT_NOFILE and : closes them all with a few exceptions. : : Turns out that takes a long time when your limit -n is now 2^20 (1048576). : : With 2.6.27.* the ulimit -n was the standard 1024, but with 2.6.28 it is : now a thousand times that. : : 2.6.28 included a patch titled "rlimit: permit setting RLIMIT_NOFILE to : RLIM_INFINITY" (0c2d64fb6cae9aae480f6a46cfe79f8d7d48b59f)[1] that : allows, as the title implies, to set the limit for number of files to : infinity. : : Closer investigation showed that the broken default ulimit did not apply : to "system" processes (like stuff started from init). In the end I : could establish that all processes that passed through pam_limit at one : point had the bad resource limit. : : Apparently the pam library in Debian etch (4.0) initializes the limits : to some default values when it doesn't have any settings in limit.conf : to override them. Turns out that for nofiles this is RLIM_INFINITY. : Commenting out "case RLIMIT_NOFILE" in pam_limit.c:267 of our pam : package version 0.79-5 fixes that - tho I'm not sure what side effects : that has. : : Debian lenny (the upcoming 5.0 version) doesn't have this issue as it : uses a different pam (version). Reported-by: Peter Palfrader Cc: Adam Tkac Cc: Michael Kerrisk Cc: [2.6.28.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sys.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/sys.c b/kernel/sys.c index e7dc0e10a485..f145c415bc16 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1525,22 +1525,14 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) return -EINVAL; if (copy_from_user(&new_rlim, rlim, sizeof(*rlim))) return -EFAULT; + if (new_rlim.rlim_cur > new_rlim.rlim_max) + return -EINVAL; old_rlim = current->signal->rlim + resource; if ((new_rlim.rlim_max > old_rlim->rlim_max) && !capable(CAP_SYS_RESOURCE)) return -EPERM; - - if (resource == RLIMIT_NOFILE) { - if (new_rlim.rlim_max == RLIM_INFINITY) - new_rlim.rlim_max = sysctl_nr_open; - if (new_rlim.rlim_cur == RLIM_INFINITY) - new_rlim.rlim_cur = sysctl_nr_open; - if (new_rlim.rlim_max > sysctl_nr_open) - return -EPERM; - } - - if (new_rlim.rlim_cur > new_rlim.rlim_max) - return -EINVAL; + if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open) + return -EPERM; retval = security_task_setrlimit(resource, &new_rlim); if (retval) -- cgit v1.2.3 From 777c6c5f1f6e757ae49ecca2ed72d6b1f523c007 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 4 Feb 2009 15:12:14 -0800 Subject: wait: prevent exclusive waiter starvation With exclusive waiters, every process woken up through the wait queue must ensure that the next waiter down the line is woken when it has finished. Interruptible waiters don't do that when aborting due to a signal. And if an aborting waiter is concurrently woken up through the waitqueue, noone will ever wake up the next waiter. This has been observed with __wait_on_bit_lock() used by lock_page_killable(): the first contender on the queue was aborting when the actual lock holder woke it up concurrently. The aborted contender didn't acquire the lock and therefor never did an unlock followed by waking up the next waiter. Add abort_exclusive_wait() which removes the process' wait descriptor from the waitqueue, iff still queued, or wakes up the next waiter otherwise. It does so under the waitqueue lock. Racing with a wake up means the aborting process is either already woken (removed from the queue) and will wake up the next waiter, or it will remove itself from the queue and the concurrent wake up will apply to the next waiter after it. Use abort_exclusive_wait() in __wait_event_interruptible_exclusive() and __wait_on_bit_lock() when they were interrupted by other means than a wake up through the queue. [akpm@linux-foundation.org: coding-style fixes] Reported-by: Chris Mason Signed-off-by: Johannes Weiner Mentored-by: Oleg Nesterov Cc: Peter Zijlstra Cc: Matthew Wilcox Cc: Chuck Lever Cc: Nick Piggin Cc: Ingo Molnar Cc: ["after some testing"] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/wait.h | 11 ++++++++-- kernel/sched.c | 4 ++-- kernel/wait.c | 59 +++++++++++++++++++++++++++++++++++++++++++++------- 3 files changed, 63 insertions(+), 11 deletions(-) (limited to 'kernel') diff --git a/include/linux/wait.h b/include/linux/wait.h index ef609f842fac..a210ede73b56 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -132,6 +132,8 @@ static inline void __remove_wait_queue(wait_queue_head_t *head, list_del(&old->task_list); } +void __wake_up_common(wait_queue_head_t *q, unsigned int mode, + int nr_exclusive, int sync, void *key); void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key); extern void __wake_up_locked(wait_queue_head_t *q, unsigned int mode); extern void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr); @@ -333,16 +335,19 @@ do { \ for (;;) { \ prepare_to_wait_exclusive(&wq, &__wait, \ TASK_INTERRUPTIBLE); \ - if (condition) \ + if (condition) { \ + finish_wait(&wq, &__wait); \ break; \ + } \ if (!signal_pending(current)) { \ schedule(); \ continue; \ } \ ret = -ERESTARTSYS; \ + abort_exclusive_wait(&wq, &__wait, \ + TASK_INTERRUPTIBLE, NULL); \ break; \ } \ - finish_wait(&wq, &__wait); \ } while (0) #define wait_event_interruptible_exclusive(wq, condition) \ @@ -431,6 +436,8 @@ extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state); void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state); void finish_wait(wait_queue_head_t *q, wait_queue_t *wait); +void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, + unsigned int mode, void *key); int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key); int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key); diff --git a/kernel/sched.c b/kernel/sched.c index 242d0d47a70d..8ee437a5ec1d 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4697,8 +4697,8 @@ EXPORT_SYMBOL(default_wake_function); * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns * zero in this (rare) case, and we handle it by continuing to scan the queue. */ -static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, - int nr_exclusive, int sync, void *key) +void __wake_up_common(wait_queue_head_t *q, unsigned int mode, + int nr_exclusive, int sync, void *key) { wait_queue_t *curr, *next; diff --git a/kernel/wait.c b/kernel/wait.c index cd87131f2fc2..42a2dbc181c8 100644 --- a/kernel/wait.c +++ b/kernel/wait.c @@ -91,6 +91,15 @@ prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state) } EXPORT_SYMBOL(prepare_to_wait_exclusive); +/* + * finish_wait - clean up after waiting in a queue + * @q: waitqueue waited on + * @wait: wait descriptor + * + * Sets current thread back to running state and removes + * the wait descriptor from the given waitqueue if still + * queued. + */ void finish_wait(wait_queue_head_t *q, wait_queue_t *wait) { unsigned long flags; @@ -117,6 +126,39 @@ void finish_wait(wait_queue_head_t *q, wait_queue_t *wait) } EXPORT_SYMBOL(finish_wait); +/* + * abort_exclusive_wait - abort exclusive waiting in a queue + * @q: waitqueue waited on + * @wait: wait descriptor + * @state: runstate of the waiter to be woken + * @key: key to identify a wait bit queue or %NULL + * + * Sets current thread back to running state and removes + * the wait descriptor from the given waitqueue if still + * queued. + * + * Wakes up the next waiter if the caller is concurrently + * woken up through the queue. + * + * This prevents waiter starvation where an exclusive waiter + * aborts and is woken up concurrently and noone wakes up + * the next waiter. + */ +void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, + unsigned int mode, void *key) +{ + unsigned long flags; + + __set_current_state(TASK_RUNNING); + spin_lock_irqsave(&q->lock, flags); + if (!list_empty(&wait->task_list)) + list_del_init(&wait->task_list); + else if (waitqueue_active(q)) + __wake_up_common(q, mode, 1, 0, key); + spin_unlock_irqrestore(&q->lock, flags); +} +EXPORT_SYMBOL(abort_exclusive_wait); + int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key) { int ret = default_wake_function(wait, mode, sync, key); @@ -177,17 +219,20 @@ int __sched __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q, int (*action)(void *), unsigned mode) { - int ret = 0; - do { + int ret; + prepare_to_wait_exclusive(wq, &q->wait, mode); - if (test_bit(q->key.bit_nr, q->key.flags)) { - if ((ret = (*action)(q->key.flags))) - break; - } + if (!test_bit(q->key.bit_nr, q->key.flags)) + continue; + ret = action(q->key.flags); + if (!ret) + continue; + abort_exclusive_wait(wq, &q->wait, mode, &q->key); + return ret; } while (test_and_set_bit(q->key.bit_nr, q->key.flags)); finish_wait(wq, &q->wait); - return ret; + return 0; } EXPORT_SYMBOL(__wait_on_bit_lock); -- cgit v1.2.3 From 04ec93fe9bc98e3bd8560f79f56fed66dfae40d5 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Fri, 6 Feb 2009 08:17:19 +0000 Subject: fork.c: fix NULL pointer dereference when nr_threads == threads-max I happened to forked lots of processes, and hit NULL pointer dereference. It is because in copy_process() after checking max_threads, 0 is returned but not -EAGAIN. The bug is introduced by "CRED: Detach the credentials from task_struct" (commit f1752eec6145c97163dbce62d17cf5d928e28a27). Signed-off-by: Li Zefan Signed-off-by: David Howells Acked-by: James Morris Signed-off-by: Linus Torvalds --- kernel/fork.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 242a706e7721..6d5dbb7a13e2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1005,6 +1005,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, * triggers too late. This doesn't hurt, the check is only there * to stop root fork bombs. */ + retval = -EAGAIN; if (nr_threads >= max_threads) goto bad_fork_cleanup_count; -- cgit v1.2.3 From 7a89bbc74937cd74a6bcf109cfc7c032109639be Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Mon, 19 Jan 2009 13:45:28 +0100 Subject: async: Fix running list handling. async_schedule() should pass in async_running as the running list, and run_one_entry() should put the entry to be run on the provided running list instead of always on the generic one. Reported-by: Jonathan Corbet Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven --- kernel/async.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/async.c b/kernel/async.c index 67a2be71f517..0c90d500ab68 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -133,7 +133,7 @@ static void run_one_entry(void) /* 2) move it to the running queue */ list_del(&entry->list); - list_add_tail(&entry->list, &async_running); + list_add_tail(&entry->list, entry->running); spin_unlock_irqrestore(&async_lock, flags); /* 3) run it (and print duration)*/ @@ -210,7 +210,7 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, struct l async_cookie_t async_schedule(async_func_ptr *ptr, void *data) { - return __async_schedule(ptr, data, &async_pending); + return __async_schedule(ptr, data, &async_running); } EXPORT_SYMBOL_GPL(async_schedule); -- cgit v1.2.3 From 86532d8b167e71e24da8b564348b52977b76d15f Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Mon, 19 Jan 2009 13:45:31 +0100 Subject: async: Handle kthread_run() return codes. If we fail to create the manager thread, fall back to non-fastboot. If we fail to create an async thread, try again after waiting for a bit. Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven --- kernel/async.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/async.c b/kernel/async.c index 0c90d500ab68..078d5ed150d1 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -54,6 +54,7 @@ asynchronous and synchronous parts of the kernel. #include #include #include +#include #include static async_cookie_t next_cookie = 1; @@ -319,7 +320,11 @@ static int async_manager_thread(void *unused) ec = atomic_read(&entry_count); while (tc < ec && tc < MAX_THREADS) { - kthread_run(async_thread, NULL, "async/%i", tc); + if (IS_ERR(kthread_run(async_thread, NULL, "async/%i", + tc))) { + msleep(100); + continue; + } atomic_inc(&thread_count); tc++; } @@ -334,7 +339,9 @@ static int async_manager_thread(void *unused) static int __init async_init(void) { if (async_enabled) - kthread_run(async_manager_thread, NULL, "async/mgr"); + if (IS_ERR(kthread_run(async_manager_thread, NULL, + "async/mgr"))) + async_enabled = 0; return 0; } -- cgit v1.2.3 From f30d5b307c694e03368ab55f2f96b0ca4131e775 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Mon, 19 Jan 2009 13:45:33 +0100 Subject: async: Add some documentation. Add some kerneldoc to the async interface. Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven --- kernel/async.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'kernel') diff --git a/kernel/async.c b/kernel/async.c index 078d5ed150d1..b5f0d4b94937 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -209,18 +209,43 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, struct l return newcookie; } +/** + * async_schedule - schedule a function for asynchronous execution + * @ptr: function to execute asynchronously + * @data: data pointer to pass to the function + * + * Returns an async_cookie_t that may be used for checkpointing later. + * Note: This function may be called from atomic or non-atomic contexts. + */ async_cookie_t async_schedule(async_func_ptr *ptr, void *data) { return __async_schedule(ptr, data, &async_running); } EXPORT_SYMBOL_GPL(async_schedule); +/** + * async_schedule_special - schedule a function for asynchronous execution with a special running queue + * @ptr: function to execute asynchronously + * @data: data pointer to pass to the function + * @running: list head to add to while running + * + * Returns an async_cookie_t that may be used for checkpointing later. + * @running may be used in the async_synchronize_*_special() functions + * to wait on a special running queue rather than on the global running + * queue. + * Note: This function may be called from atomic or non-atomic contexts. + */ async_cookie_t async_schedule_special(async_func_ptr *ptr, void *data, struct list_head *running) { return __async_schedule(ptr, data, running); } EXPORT_SYMBOL_GPL(async_schedule_special); +/** + * async_synchronize_full - synchronize all asynchronous function calls + * + * This function waits until all asynchronous function calls have been done. + */ void async_synchronize_full(void) { do { @@ -229,12 +254,27 @@ void async_synchronize_full(void) } EXPORT_SYMBOL_GPL(async_synchronize_full); +/** + * async_synchronize_full_special - synchronize all asynchronous function calls for a running list + * @list: running list to synchronize on + * + * This function waits until all asynchronous function calls for the running + * list @list have been done. + */ void async_synchronize_full_special(struct list_head *list) { async_synchronize_cookie_special(next_cookie, list); } EXPORT_SYMBOL_GPL(async_synchronize_full_special); +/** + * async_synchronize_cookie_special - synchronize asynchronous function calls on a running list with cookie checkpointing + * @cookie: async_cookie_t to use as checkpoint + * @running: running list to synchronize on + * + * This function waits until all asynchronous function calls for the running + * list @list submitted prior to @cookie have been done. + */ void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *running) { ktime_t starttime, delta, endtime; @@ -257,6 +297,13 @@ void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *r } EXPORT_SYMBOL_GPL(async_synchronize_cookie_special); +/** + * async_synchronize_cookie - synchronize asynchronous function calls with cookie checkpointing + * @cookie: async_cookie_t to use as checkpoint + * + * This function waits until all asynchronous function calls prior to @cookie + * have been done. + */ void async_synchronize_cookie(async_cookie_t cookie) { async_synchronize_cookie_special(cookie, &async_running); -- cgit v1.2.3 From 766ccb9ed406c230d13c145def08ebea1b932982 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Tue, 20 Jan 2009 15:31:31 +0100 Subject: async: Rename _special -> _domain for clarity. Rename the async_*_special() functions to async_*_domain(), which describes the purpose of these functions much better. [Broke up long lines to silence checkpatch] Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven --- fs/super.c | 4 ++-- include/linux/async.h | 8 +++++--- kernel/async.c | 41 ++++++++++++++++++++++------------------- 3 files changed, 29 insertions(+), 24 deletions(-) (limited to 'kernel') diff --git a/fs/super.c b/fs/super.c index 645e5403f2a0..61dce001dd57 100644 --- a/fs/super.c +++ b/fs/super.c @@ -301,7 +301,7 @@ void generic_shutdown_super(struct super_block *sb) /* * wait for asynchronous fs operations to finish before going further */ - async_synchronize_full_special(&sb->s_async_list); + async_synchronize_full_domain(&sb->s_async_list); /* bad name - it should be evict_inodes() */ invalidate_inodes(sb); @@ -470,7 +470,7 @@ restart: sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); - async_synchronize_full_special(&sb->s_async_list); + async_synchronize_full_domain(&sb->s_async_list); if (sb->s_root && (wait || sb->s_dirt)) sb->s_op->sync_fs(sb, wait); up_read(&sb->s_umount); diff --git a/include/linux/async.h b/include/linux/async.h index c4ecacd0b327..68a9530196f2 100644 --- a/include/linux/async.h +++ b/include/linux/async.h @@ -17,9 +17,11 @@ typedef u64 async_cookie_t; typedef void (async_func_ptr) (void *data, async_cookie_t cookie); extern async_cookie_t async_schedule(async_func_ptr *ptr, void *data); -extern async_cookie_t async_schedule_special(async_func_ptr *ptr, void *data, struct list_head *list); +extern async_cookie_t async_schedule_domain(async_func_ptr *ptr, void *data, + struct list_head *list); extern void async_synchronize_full(void); -extern void async_synchronize_full_special(struct list_head *list); +extern void async_synchronize_full_domain(struct list_head *list); extern void async_synchronize_cookie(async_cookie_t cookie); -extern void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *list); +extern void async_synchronize_cookie_domain(async_cookie_t cookie, + struct list_head *list); diff --git a/kernel/async.c b/kernel/async.c index b5f0d4b94937..e23399d88bac 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -224,22 +224,23 @@ async_cookie_t async_schedule(async_func_ptr *ptr, void *data) EXPORT_SYMBOL_GPL(async_schedule); /** - * async_schedule_special - schedule a function for asynchronous execution with a special running queue + * async_schedule_domain - schedule a function for asynchronous execution within a certain domain * @ptr: function to execute asynchronously * @data: data pointer to pass to the function - * @running: list head to add to while running + * @running: running list for the domain * * Returns an async_cookie_t that may be used for checkpointing later. - * @running may be used in the async_synchronize_*_special() functions - * to wait on a special running queue rather than on the global running - * queue. + * @running may be used in the async_synchronize_*_domain() functions + * to wait within a certain synchronization domain rather than globally. + * A synchronization domain is specified via the running queue @running to use. * Note: This function may be called from atomic or non-atomic contexts. */ -async_cookie_t async_schedule_special(async_func_ptr *ptr, void *data, struct list_head *running) +async_cookie_t async_schedule_domain(async_func_ptr *ptr, void *data, + struct list_head *running) { return __async_schedule(ptr, data, running); } -EXPORT_SYMBOL_GPL(async_schedule_special); +EXPORT_SYMBOL_GPL(async_schedule_domain); /** * async_synchronize_full - synchronize all asynchronous function calls @@ -255,27 +256,29 @@ void async_synchronize_full(void) EXPORT_SYMBOL_GPL(async_synchronize_full); /** - * async_synchronize_full_special - synchronize all asynchronous function calls for a running list + * async_synchronize_full_domain - synchronize all asynchronous function within a certain domain * @list: running list to synchronize on * - * This function waits until all asynchronous function calls for the running - * list @list have been done. + * This function waits until all asynchronous function calls for the + * synchronization domain specified by the running list @list have been done. */ -void async_synchronize_full_special(struct list_head *list) +void async_synchronize_full_domain(struct list_head *list) { - async_synchronize_cookie_special(next_cookie, list); + async_synchronize_cookie_domain(next_cookie, list); } -EXPORT_SYMBOL_GPL(async_synchronize_full_special); +EXPORT_SYMBOL_GPL(async_synchronize_full_domain); /** - * async_synchronize_cookie_special - synchronize asynchronous function calls on a running list with cookie checkpointing + * async_synchronize_cookie_domain - synchronize asynchronous function calls within a certain domain with cookie checkpointing * @cookie: async_cookie_t to use as checkpoint * @running: running list to synchronize on * - * This function waits until all asynchronous function calls for the running - * list @list submitted prior to @cookie have been done. + * This function waits until all asynchronous function calls for the + * synchronization domain specified by the running list @list submitted + * prior to @cookie have been done. */ -void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *running) +void async_synchronize_cookie_domain(async_cookie_t cookie, + struct list_head *running) { ktime_t starttime, delta, endtime; @@ -295,7 +298,7 @@ void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *r (long long)ktime_to_ns(delta) >> 10); } } -EXPORT_SYMBOL_GPL(async_synchronize_cookie_special); +EXPORT_SYMBOL_GPL(async_synchronize_cookie_domain); /** * async_synchronize_cookie - synchronize asynchronous function calls with cookie checkpointing @@ -306,7 +309,7 @@ EXPORT_SYMBOL_GPL(async_synchronize_cookie_special); */ void async_synchronize_cookie(async_cookie_t cookie) { - async_synchronize_cookie_special(cookie, &async_running); + async_synchronize_cookie_domain(cookie, &async_running); } EXPORT_SYMBOL_GPL(async_synchronize_cookie); -- cgit v1.2.3 From f7de7621f07495ad14fb23a812003bcf8f6af65a Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Mon, 2 Feb 2009 13:24:34 +0100 Subject: async: use list_move_tail list.h provides a dedicated primitive for "list_del followed by list_add_tail"... list_move_tail. Signed-off-by: Arjan van de Ven Signed-off-by: Stefan Richter --- kernel/async.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/async.c b/kernel/async.c index e23399d88bac..f565891f2c9b 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -133,8 +133,7 @@ static void run_one_entry(void) entry = list_first_entry(&async_pending, struct async_entry, list); /* 2) move it to the running queue */ - list_del(&entry->list); - list_add_tail(&entry->list, entry->running); + list_move_tail(&entry->list, entry->running); spin_unlock_irqrestore(&async_lock, flags); /* 3) run it (and print duration)*/ -- cgit v1.2.3