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Commit bbbee908 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: Ammend cleanup in fork() fail 



When fork() fails we cannot use perf_counter_exit_task() since that
assumes to operate on current. Write a new helper that cleans up
unused/clean contexts.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 665c2142

include/linux/perf_counter.h

+2 −0
Original line number Diff line number Diff line
@@ -579,6 +579,7 @@ extern void perf_counter_task_sched_out(struct task_struct *task, 
extern void perf_counter_task_tick(struct task_struct *task, int cpu);

extern int perf_counter_init_task(struct task_struct *child);

extern void perf_counter_exit_task(struct task_struct *child);

extern void perf_counter_free_task(struct task_struct *task);

extern void perf_counter_do_pending(void);

extern void perf_counter_print_debug(void);

extern void __perf_disable(void);
@@ -644,6 +645,7 @@ static inline void 
perf_counter_task_tick(struct task_struct *task, int cpu)		{ }

static inline int perf_counter_init_task(struct task_struct *child)	{ return 0; }

static inline void perf_counter_exit_task(struct task_struct *child)	{ }

static inline void perf_counter_free_task(struct task_struct *task)	{ }

static inline void perf_counter_do_pending(void)			{ }

static inline void perf_counter_print_debug(void)			{ }

static inline void perf_disable(void)					{ }

kernel/fork.c

+1 −1
Original line number Diff line number Diff line
@@ -1298,7 +1298,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
bad_fork_cleanup_audit:

	audit_free(p);

bad_fork_cleanup_policy:

	perf_counter_exit_task(p);

	perf_counter_free_task(p);

#ifdef CONFIG_NUMA

	mpol_put(p->mempolicy);

bad_fork_cleanup_cgroup:

kernel/perf_counter.c

+40 −3
Original line number Diff line number Diff line
@@ -3538,8 +3538,7 @@ static void sync_child_counter(struct perf_counter *child_counter, 
}



static void

__perf_counter_exit_task(struct task_struct *child,

			 struct perf_counter *child_counter,

__perf_counter_exit_task(struct perf_counter *child_counter,

			 struct perf_counter_context *child_ctx)

{

	struct perf_counter *parent_counter;
@@ -3605,7 +3604,7 @@ void perf_counter_exit_task(struct task_struct *child) 
again:

	list_for_each_entry_safe(child_counter, tmp, &child_ctx->counter_list,

				 list_entry)

		__perf_counter_exit_task(child, child_counter, child_ctx);

		__perf_counter_exit_task(child_counter, child_ctx);



	/*

	 * If the last counter was a group counter, it will have appended all
@@ -3620,6 +3619,44 @@ void perf_counter_exit_task(struct task_struct *child) 
	put_ctx(child_ctx);

}



/*

 * free an unexposed, unused context as created by inheritance by

 * init_task below, used by fork() in case of fail.

 */

void perf_counter_free_task(struct task_struct *task)

{

	struct perf_counter_context *ctx = task->perf_counter_ctxp;

	struct perf_counter *counter, *tmp;



	if (!ctx)

		return;



	mutex_lock(&ctx->mutex);

again:

	list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry) {

		struct perf_counter *parent = counter->parent;



		if (WARN_ON_ONCE(!parent))

			continue;



		mutex_lock(&parent->child_mutex);

		list_del_init(&counter->child_list);

		mutex_unlock(&parent->child_mutex);



		fput(parent->filp);



		list_del_counter(counter, ctx);

		free_counter(counter);

	}



	if (!list_empty(&ctx->counter_list))

		goto again;



	mutex_unlock(&ctx->mutex);



	put_ctx(ctx);

}



/*

 * Initialize the perf_counter context in task_struct

 */