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SubjectRe: [PATCH 1/1] function trace: fix a bug of single thread function trace

* Liming Wang <liming.wang@windriver.com> wrote:

> Impact: fix a bug in ftrace_update_pid_func
>
> When disabling single thread function trace using
> "echo -1 > set_ftrace_pid", the normal function trace
> has to restore to original function, otherwise the normal
> function trace will not work well.
> Without this commit, something like below:
>
> $ ps |grep 850
> 850 root 2556 S -/bin/sh
> $ echo 850 > /debug/tracing/set_ftrace_pid
> $ echo function > /debug/tracing/current_tracer
> $ echo 1 > /debug/tracing/tracing_enabled
> $ sleep 1
> $ echo 0 > /debug/tracing/tracing_enabled
> $ cat /debug/tracing/trace_pipe |wc -l
> 59704
> $ echo -1 > /debug/tracing/set_ftrace_pid
> $ echo 1 > /debug/tracing/tracing_enabled
> $ sleep 1
> $ echo 0 > /debug/tracing/tracing_enabled
> $ more /debug/tracing/trace_pipe
> <====== nothing output now!
> it should output trace record.
>
> Signed-off-by: Liming Wang <liming.wang@windriver.com>
> ---
> kernel/trace/ftrace.c | 6 ++----
> 1 files changed, 2 insertions(+), 4 deletions(-)

applied to tip/tracing/ftrace, thanks!

Ingo


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