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authorFrederic Weisbecker <fweisbec@gmail.com>2010-05-27 21:34:58 +0200
committerIngo Molnar <mingo@elte.hu>2010-05-31 08:46:10 +0200
commit74048f895fa8cbf8119b4999f1f44881a825f954 (patch)
tree16c38467e68c730d459dd64cee7f749f1745c782 /kernel/perf_event.c
parent90151c35b19633e0cab5a6c80f1ba4a51e7c913b (diff)
perf_events: Fix unincremented buffer base on partial copy
If a sample size crosses to the next page boundary, the copy will be made in more than one step. However we forget to advance the source offset for the next copy, leading to unexpected double copies that completely mess up the traces. This fixes various kinds of bad traces that have irrelevant data inside, as an example: geany-4979 [001] 5758.077775: sched_switch: prev_comm=! prev_pid=121 prev_prio=0 prev_state=S|D|Z|X|x ==> next_comm= next_pid=7497072 next_prio=0 Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1274988898-5639-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r--kernel/perf_event.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 42a0e9191af..858f56fa243 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3064,6 +3064,7 @@ __always_inline void perf_output_copy(struct perf_output_handle *handle,
len -= size;
handle->addr += size;
+ buf += size;
handle->size -= size;
if (!handle->size) {
struct perf_mmap_data *data = handle->data;