[tip:perf/urgent] perf_events: Fix unincremented buffer base on partial copy
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From: tip-bot for Frederic Weisbecker on 31 May 2010 03:30 Commit-ID: 74048f895fa8cbf8119b4999f1f44881a825f954 Gitweb: http://git.kernel.org/tip/74048f895fa8cbf8119b4999f1f44881a825f954 Author: Frederic Weisbecker <fweisbec(a)gmail.com> AuthorDate: Thu, 27 May 2010 21:34:58 +0200 Committer: Ingo Molnar <mingo(a)elte.hu> CommitDate: Mon, 31 May 2010 08:46:10 +0200 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(a)gmail.com> Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com> Cc: Paul Mackerras <paulus(a)samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl> LKML-Reference: <1274988898-5639-1-git-send-regression-fweisbec(a)gmail.com> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- kernel/perf_event.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 42a0e91..858f56f 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |