Commit-ID: 91d876bd14c82826b69bf23f502cb283959ebb1f
Gitweb: http://git.kernel.org/tip/91d876bd14c82826b69bf23f502cb283959ebb1f
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Wed, 25 Mar 2009 12:30:24 +0100
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 25 Mar 2009 13:02:52 +0100
perf_counter: sanity check on the output API
Ensure we never write more than we said we would.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
LKML-Reference: <20090325113316.921433024@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/perf_counter.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index d76e311..7669afe 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1422,6 +1422,7 @@ struct perf_output_handle {
struct perf_counter *counter;
struct perf_mmap_data *data;
unsigned int offset;
+ unsigned int head;
int wakeup;
};
@@ -1447,6 +1448,7 @@ static int perf_output_begin(struct perf_output_handle *handle,
handle->counter = counter;
handle->data = data;
handle->offset = offset;
+ handle->head = head;
handle->wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT);
return 0;
@@ -1485,6 +1487,8 @@ static void perf_output_copy(struct perf_output_handle *handle,
} while (len);
handle->offset = offset;
+
+ WARN_ON_ONCE(handle->offset > handle->head);
}
#define perf_output_put(handle, x) \
--
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