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Commit 75f937f2 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: Fix ctx->mutex vs counter->mutex inversion 



Simon triggered a lockdep inversion report about us taking ctx->mutex
vs counter->mutex in inverse orders. Fix that up.

Reported-by: default avatarSimon Holm Thøgersen <odie@cs.aau.dk>
Tested-by: default avatarSimon Holm Thøgersen <odie@cs.aau.dk>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 613d8602

kernel/perf_counter.c

+11 −23
Original line number Diff line number Diff line
@@ -1620,22 +1620,6 @@ static void perf_counter_reset(struct perf_counter *counter) 
	perf_counter_update_userpage(counter);

}



static void perf_counter_for_each_sibling(struct perf_counter *counter,

					  void (*func)(struct perf_counter *))

{

	struct perf_counter_context *ctx = counter->ctx;

	struct perf_counter *sibling;



	WARN_ON_ONCE(ctx->parent_ctx);

	mutex_lock(&ctx->mutex);

	counter = counter->group_leader;



	func(counter);

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

		func(sibling);

	mutex_unlock(&ctx->mutex);

}



/*

 * Holding the top-level counter's child_mutex means that any

 * descendant process that has inherited this counter will block
@@ -1658,14 +1642,18 @@ static void perf_counter_for_each_child(struct perf_counter *counter, 
static void perf_counter_for_each(struct perf_counter *counter,

				  void (*func)(struct perf_counter *))

{

	struct perf_counter *child;

	struct perf_counter_context *ctx = counter->ctx;

	struct perf_counter *sibling;



	WARN_ON_ONCE(counter->ctx->parent_ctx);

	mutex_lock(&counter->child_mutex);

	perf_counter_for_each_sibling(counter, func);

	list_for_each_entry(child, &counter->child_list, child_list)

		perf_counter_for_each_sibling(child, func);

	mutex_unlock(&counter->child_mutex);

	WARN_ON_ONCE(ctx->parent_ctx);

	mutex_lock(&ctx->mutex);

	counter = counter->group_leader;



	perf_counter_for_each_child(counter, func);

	func(counter);

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

		perf_counter_for_each_child(counter, func);

	mutex_unlock(&ctx->mutex);

}



static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)