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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2009-07-28 20:17:22 +0800 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2009-07-28 23:17:23 +0200 |
| commit | 74e7ff8c50b6b022e6ffaa736b16a4dc161d3eaf (patch) | |
| tree | 5bbe7b9f239f1e7b0a688b521f5dca8b9ea99ef4 /kernel | |
| parent | 38ceb592fcac9110c6b3c87ea0a27bff68c43486 (diff) | |
| download | linux-74e7ff8c50b6b022e6ffaa736b16a4dc161d3eaf.tar.gz | |
tracing: Fix missing function_graph events when we splice_read from trace_pipe
About a half events are missing when we splice_read
from trace_pipe. They are unexpectedly consumed because we ignore
the TRACE_TYPE_NO_CONSUME return value used by the function graph
tracer when it needs to consume the events by itself to walk on
the ring buffer.
The same problem appears with ftrace_dump()
Example of an output before this patch:
1) | ktime_get_real() {
1) 2.846 us | read_hpet();
1) 4.558 us | }
1) 6.195 us | }
After this patch:
0) | ktime_get_real() {
0) | getnstimeofday() {
0) 1.960 us | read_hpet();
0) 3.597 us | }
0) 5.196 us | }
The fix also applies on 2.6.30
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@kernel.org
LKML-Reference: <4A6EEC52.90704@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8bc8d8afea6a..da984ad065ab 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3085,7 +3085,8 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter) break; } - trace_consume(iter); + if (ret != TRACE_TYPE_NO_CONSUME) + trace_consume(iter); rem -= count; if (!find_next_entry_inc(iter)) { rem = 0; @@ -4233,8 +4234,11 @@ static void __ftrace_dump(bool disable_tracing) iter.pos = -1; if (find_next_entry_inc(&iter) != NULL) { - print_trace_line(&iter); - trace_consume(&iter); + int ret; + + ret = print_trace_line(&iter); + if (ret != TRACE_TYPE_NO_CONSUME) + trace_consume(&iter); } trace_printk_seq(&iter.seq); |