Commit-ID: ca0dd44cf37bfe316751e1701439c3ff44beb05c
Gitweb: https://git.kernel.org/tip/ca0dd44cf37bfe316751e1701439c3ff44beb05c
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 5 Sep 2017 13:23:44 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 27 Oct 2017 10:31:57 +0200
perf/core: Fix perf_event_read_value() locking
perf_event_read_value() is an external accessor, just like
perf_event_{en,dis}able() and should thus use perf_event_ctx_lock().
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: f63a8daa5812 ("perf: Fix event->ctx locking")
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 74671e1..d636f1d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4398,7 +4398,7 @@ static int perf_release(struct inode *inode, struct file *file)
return 0;
}
-u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+static u64 __perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
{
struct perf_event *child;
u64 total = 0;
@@ -4426,6 +4426,18 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
return total;
}
+
+u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+{
+ struct perf_event_context *ctx;
+ u64 count;
+
+ ctx = perf_event_ctx_lock(event);
+ count = __perf_event_read_value(event, enabled, running);
+ perf_event_ctx_unlock(event, ctx);
+
+ return count;
+}
EXPORT_SYMBOL_GPL(perf_event_read_value);
static int __perf_read_group_add(struct perf_event *leader,
@@ -4528,7 +4540,7 @@ static int perf_read_one(struct perf_event *event,
u64 values[4];
int n = 0;
- values[n++] = perf_event_read_value(event, &enabled, &running);
+ values[n++] = __perf_event_read_value(event, &enabled, &running);
if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
values[n++] = enabled;
if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
--
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