From 74048f895fa8cbf8119b4999f1f44881a825f954 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 27 May 2010 21:34:58 +0200 Subject: [PATCH] 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 Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Signed-off-by: Peter Zijlstra LKML-Reference: <1274988898-5639-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 42a0e9191af5..858f56fa2432 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; -- 2.20.1