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Commit c54894cd authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 

Pull workqueue changes from Tejun Heo:
 "Nothing exciting.  Most are updates to debug stuff and related fixes.
  Two not-too-critical bugs are fixed - WARN_ON() triggering spurious
  during cpu offlining and unlikely lockdep related oops."

* 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  lockdep: fix oops in processing workqueue
  workqueue: skip nr_running sanity check in worker_enter_idle() if trustee is active
  workqueue: Catch more locking problems with flush_work()
  workqueue: change BUG_ON() to WARN_ON()
  trace: Remove unused workqueue tracer
parents fb09bafd 4d82a1de

include/linux/lockdep.h

+18 −0
Original line number Diff line number Diff line
@@ -157,6 +157,24 @@ struct lockdep_map { 
#endif

};



static inline void lockdep_copy_map(struct lockdep_map *to,

				    struct lockdep_map *from)

{

	int i;



	*to = *from;

	/*

	 * Since the class cache can be modified concurrently we could observe

	 * half pointers (64bit arch using 32bit copy insns). Therefore clear

	 * the caches and take the performance hit.

	 *

	 * XXX it doesn't work well with lockdep_set_class_and_subclass(), since

	 *     that relies on cache abuse.

	 */

	for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)

		to->class_cache[i] = NULL;

}



/*

 * Every lock has a list of other locks that were taken after it.

 * We only grow the list, never remove from it:

kernel/timer.c

+3 −1
Original line number Diff line number Diff line
@@ -1108,7 +1108,9 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long), 
	 * warnings as well as problems when looking into

	 * timer->lockdep_map, make a copy and use that here.

	 */

	struct lockdep_map lockdep_map = timer->lockdep_map;

	struct lockdep_map lockdep_map;



	lockdep_copy_map(&lockdep_map, &timer->lockdep_map);

#endif

	/*

	 * Couple the lock chain with the lock chain at

kernel/trace/Makefile

+0 −1
Original line number Diff line number Diff line
@@ -41,7 +41,6 @@ obj-$(CONFIG_STACK_TRACER) += trace_stack.o 
obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += trace_functions_graph.o

obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o

obj-$(CONFIG_WORKQUEUE_TRACER) += trace_workqueue.o

obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o

ifeq ($(CONFIG_BLOCK),y)

obj-$(CONFIG_EVENT_TRACING) += blktrace.o

kernel/trace/trace_workqueue.c

deleted100644 → 0
+0 −300
Original line number Diff line number Diff line 
/*

 * Workqueue statistical tracer.

 *

 * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>

 *

 */





#include <trace/events/workqueue.h>

#include <linux/list.h>

#include <linux/percpu.h>

#include <linux/slab.h>

#include <linux/kref.h>

#include "trace_stat.h"

#include "trace.h"





/* A cpu workqueue thread */

struct cpu_workqueue_stats {

	struct list_head            list;

	struct kref                 kref;

	int		            cpu;

	pid_t			    pid;

/* Can be inserted from interrupt or user context, need to be atomic */

	atomic_t	            inserted;

/*

 *  Don't need to be atomic, works are serialized in a single workqueue thread

 *  on a single CPU.

 */

	unsigned int		    executed;

};



/* List of workqueue threads on one cpu */

struct workqueue_global_stats {

	struct list_head	list;

	spinlock_t		lock;

};



/* Don't need a global lock because allocated before the workqueues, and

 * never freed.

 */

static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);

#define workqueue_cpu_stat(cpu) (&per_cpu(all_workqueue_stat, cpu))



static void cpu_workqueue_stat_free(struct kref *kref)

{

	kfree(container_of(kref, struct cpu_workqueue_stats, kref));

}



/* Insertion of a work */

static void

probe_workqueue_insertion(void *ignore,

			  struct task_struct *wq_thread,

			  struct work_struct *work)

{

	int cpu = cpumask_first(&wq_thread->cpus_allowed);

	struct cpu_workqueue_stats *node;

	unsigned long flags;



	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);

	list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {

		if (node->pid == wq_thread->pid) {

			atomic_inc(&node->inserted);

			goto found;

		}

	}

	pr_debug("trace_workqueue: entry not found\n");

found:

	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

}



/* Execution of a work */

static void

probe_workqueue_execution(void *ignore,

			  struct task_struct *wq_thread,

			  struct work_struct *work)

{

	int cpu = cpumask_first(&wq_thread->cpus_allowed);

	struct cpu_workqueue_stats *node;

	unsigned long flags;



	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);

	list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {

		if (node->pid == wq_thread->pid) {

			node->executed++;

			goto found;

		}

	}

	pr_debug("trace_workqueue: entry not found\n");

found:

	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

}



/* Creation of a cpu workqueue thread */

static void probe_workqueue_creation(void *ignore,

				     struct task_struct *wq_thread, int cpu)

{

	struct cpu_workqueue_stats *cws;

	unsigned long flags;



	WARN_ON(cpu < 0);



	/* Workqueues are sometimes created in atomic context */

	cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);

	if (!cws) {

		pr_warning("trace_workqueue: not enough memory\n");

		return;

	}

	INIT_LIST_HEAD(&cws->list);

	kref_init(&cws->kref);

	cws->cpu = cpu;

	cws->pid = wq_thread->pid;



	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);

	list_add_tail(&cws->list, &workqueue_cpu_stat(cpu)->list);

	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

}



/* Destruction of a cpu workqueue thread */

static void

probe_workqueue_destruction(void *ignore, struct task_struct *wq_thread)

{

	/* Workqueue only execute on one cpu */

	int cpu = cpumask_first(&wq_thread->cpus_allowed);

	struct cpu_workqueue_stats *node, *next;

	unsigned long flags;



	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);

	list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,

							list) {

		if (node->pid == wq_thread->pid) {

			list_del(&node->list);

			kref_put(&node->kref, cpu_workqueue_stat_free);

			goto found;

		}

	}



	pr_debug("trace_workqueue: don't find workqueue to destroy\n");

found:

	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);



}



static struct cpu_workqueue_stats *workqueue_stat_start_cpu(int cpu)

{

	unsigned long flags;

	struct cpu_workqueue_stats *ret = NULL;





	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);



	if (!list_empty(&workqueue_cpu_stat(cpu)->list)) {

		ret = list_entry(workqueue_cpu_stat(cpu)->list.next,

				 struct cpu_workqueue_stats, list);

		kref_get(&ret->kref);

	}



	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);



	return ret;

}



static void *workqueue_stat_start(struct tracer_stat *trace)

{

	int cpu;

	void *ret = NULL;



	for_each_possible_cpu(cpu) {

		ret = workqueue_stat_start_cpu(cpu);

		if (ret)

			return ret;

	}

	return NULL;

}



static void *workqueue_stat_next(void *prev, int idx)

{

	struct cpu_workqueue_stats *prev_cws = prev;

	struct cpu_workqueue_stats *ret;

	int cpu = prev_cws->cpu;

	unsigned long flags;



	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);

	if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {

		spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

		do {

			cpu = cpumask_next(cpu, cpu_possible_mask);

			if (cpu >= nr_cpu_ids)

				return NULL;

		} while (!(ret = workqueue_stat_start_cpu(cpu)));

		return ret;

	} else {

		ret = list_entry(prev_cws->list.next,

				 struct cpu_workqueue_stats, list);

		kref_get(&ret->kref);

	}

	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);



	return ret;

}



static int workqueue_stat_show(struct seq_file *s, void *p)

{

	struct cpu_workqueue_stats *cws = p;

	struct pid *pid;

	struct task_struct *tsk;



	pid = find_get_pid(cws->pid);

	if (pid) {

		tsk = get_pid_task(pid, PIDTYPE_PID);

		if (tsk) {

			seq_printf(s, "%3d %6d     %6u       %s\n", cws->cpu,

				   atomic_read(&cws->inserted), cws->executed,

				   tsk->comm);

			put_task_struct(tsk);

		}

		put_pid(pid);

	}



	return 0;

}



static void workqueue_stat_release(void *stat)

{

	struct cpu_workqueue_stats *node = stat;



	kref_put(&node->kref, cpu_workqueue_stat_free);

}



static int workqueue_stat_headers(struct seq_file *s)

{

	seq_printf(s, "# CPU  INSERTED  EXECUTED   NAME\n");

	seq_printf(s, "# |      |         |          |\n");

	return 0;

}



struct tracer_stat workqueue_stats __read_mostly = {

	.name = "workqueues",

	.stat_start = workqueue_stat_start,

	.stat_next = workqueue_stat_next,

	.stat_show = workqueue_stat_show,

	.stat_release = workqueue_stat_release,

	.stat_headers = workqueue_stat_headers

};





int __init stat_workqueue_init(void)

{

	if (register_stat_tracer(&workqueue_stats)) {

		pr_warning("Unable to register workqueue stat tracer\n");

		return 1;

	}



	return 0;

}

fs_initcall(stat_workqueue_init);



/*

 * Workqueues are created very early, just after pre-smp initcalls.

 * So we must register our tracepoints at this stage.

 */

int __init trace_workqueue_early_init(void)

{

	int ret, cpu;



	for_each_possible_cpu(cpu) {

		spin_lock_init(&workqueue_cpu_stat(cpu)->lock);

		INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);

	}



	ret = register_trace_workqueue_insertion(probe_workqueue_insertion, NULL);

	if (ret)

		goto out;



	ret = register_trace_workqueue_execution(probe_workqueue_execution, NULL);

	if (ret)

		goto no_insertion;



	ret = register_trace_workqueue_creation(probe_workqueue_creation, NULL);

	if (ret)

		goto no_execution;



	ret = register_trace_workqueue_destruction(probe_workqueue_destruction, NULL);

	if (ret)

		goto no_creation;



	return 0;



no_creation:

	unregister_trace_workqueue_creation(probe_workqueue_creation, NULL);

no_execution:

	unregister_trace_workqueue_execution(probe_workqueue_execution, NULL);

no_insertion:

	unregister_trace_workqueue_insertion(probe_workqueue_insertion, NULL);

out:

	pr_warning("trace_workqueue: unable to trace workqueues\n");



	return 1;

}

early_initcall(trace_workqueue_early_init);

kernel/workqueue.c

+17 −4
Original line number Diff line number Diff line
@@ -1032,7 +1032,10 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 
	cwq = get_cwq(gcwq->cpu, wq);

	trace_workqueue_queue_work(cpu, cwq, work);



	BUG_ON(!list_empty(&work->entry));

	if (WARN_ON(!list_empty(&work->entry))) {

		spin_unlock_irqrestore(&gcwq->lock, flags);

		return;

	}



	cwq->nr_in_flight[cwq->work_color]++;

	work_flags = work_color_to_flags(cwq->work_color);
@@ -1210,8 +1213,13 @@ static void worker_enter_idle(struct worker *worker) 
	} else

		wake_up_all(&gcwq->trustee_wait);



	/* sanity check nr_running */

	WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&

	/*

	 * Sanity check nr_running.  Because trustee releases gcwq->lock

	 * between setting %WORKER_ROGUE and zapping nr_running, the

	 * warning may trigger spuriously.  Check iff trustee is idle.

	 */

	WARN_ON_ONCE(gcwq->trustee_state == TRUSTEE_DONE &&

		     gcwq->nr_workers == gcwq->nr_idle &&

		     atomic_read(get_gcwq_nr_running(gcwq->cpu)));

}
@@ -1810,7 +1818,9 @@ __acquires(&gcwq->lock) 
	 * lock freed" warnings as well as problems when looking into

	 * work->lockdep_map, make a copy and use that here.

	 */

	struct lockdep_map lockdep_map = work->lockdep_map;

	struct lockdep_map lockdep_map;



	lockdep_copy_map(&lockdep_map, &work->lockdep_map);

#endif

	/*

	 * A single work shouldn't be executed concurrently by
@@ -2506,6 +2516,9 @@ bool flush_work(struct work_struct *work) 
{

	struct wq_barrier barr;



	lock_map_acquire(&work->lockdep_map);

	lock_map_release(&work->lockdep_map);



	if (start_flush_work(work, &barr, true)) {

		wait_for_completion(&barr.done);

		destroy_work_on_stack(&barr.work);