Commit 682076ae authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: Sanitize context locking 



Ensure we're consistent with the context locks.

 context->mutex
   context->lock
     list_{add,del}_counter();

so that either lock is sufficient to stabilize the context.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.618790733@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent fccc714b

kernel/perf_counter.c

+7 −2
Original line number Diff line number Diff line
@@ -597,6 +597,8 @@ static void add_counter_to_ctx(struct perf_counter *counter, 


/*

 * Cross CPU call to install and enable a performance counter

 *

 * Must be called with ctx->mutex held

 */

static void __perf_install_in_context(void *info)

{
@@ -1496,13 +1498,13 @@ static void perf_counter_for_each_sibling(struct perf_counter *counter, 
	struct perf_counter_context *ctx = counter->ctx;

	struct perf_counter *sibling;



	spin_lock_irq(&ctx->lock);

	mutex_lock(&ctx->mutex);

	counter = counter->group_leader;



	func(counter);

	list_for_each_entry(sibling, &counter->sibling_list, list_entry)

		func(sibling);

	spin_unlock_irq(&ctx->lock);

	mutex_unlock(&ctx->mutex);

}



static void perf_counter_for_each_child(struct perf_counter *counter,
@@ -3414,7 +3416,10 @@ __perf_counter_exit_task(struct task_struct *child, 
	struct perf_counter *parent_counter;



	update_counter_times(child_counter);



	spin_lock_irq(&child_ctx->lock);

	list_del_counter(child_counter, child_ctx);

	spin_unlock_irq(&child_ctx->lock);



	parent_counter = child_counter->parent;

	/*