[tip:perf/core] perf: Ensure we call add_event_to_ctx() with the right locks held

[tip-bot for Peter Zijlstra]

Commit-ID:  cee010ec5211b96f33c5c2208f5c14ebb04b634a
Gitweb:     http://git.kernel.org/tip/cee010ec5211b96f33c5c2208f5c14ebb04b634a
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Fri, 10 Sep 2010 12:51:54 +0200
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Fri, 10 Sep 2010 16:24:33 +0200

perf: Ensure we call add_event_to_ctx() with the right locks held

Even though we call it from the inherit path, where the child is
not yet accessible, we need to hold ctx->lock, add_event_to_ctx()
assumes IRQs are disabled.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 kernel/perf_event.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index eaf1c5d..f395fb4 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5913,6 +5913,7 @@ inherit_event(struct perf_event *parent_event,
 	      struct perf_event_context *child_ctx)
 {
 	struct perf_event *child_event;
+	unsigned long flags;
 
 	/*
 	 * Instead of creating recursive hierarchies of events,
@@ -5957,7 +5958,9 @@ inherit_event(struct perf_event *parent_event,
 	/*
 	 * Link it up in the child's context:
 	 */
+	raw_spin_lock_irqsave(&child_ctx->lock, flags);
 	add_event_to_ctx(child_event, child_ctx);
+	raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
 
 	/*
 	 * Get a reference to the parent filp - we will fput it
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/