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SubjectRe: [PATCH 1/2 v4] perf sched: fix wrong conversion of task state
On Mon,  1 Aug 2016 13:30:25 +0900
Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com> wrote:

> Currently sched_out_state() converts the prev_state u64 bitmask to a char
> using the bitmask as an index, which may cause invalid memory access.
> This fixes the issue by using the __ffs() returned value as an index.

OK, looks good to me:)

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks!

>
> Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
> Fixes: cdce9d738b91e ("perf sched: Add sched latency profiling")
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> Changes from v3:
> Added Fixes:
> Split the patch into 2 pieces.
>
> tools/perf/builtin-sched.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 0dfe8df..ce9bef6 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -897,9 +897,10 @@ static int thread_atoms_insert(struct perf_sched *sched, struct thread *thread)
>
> static char sched_out_state(u64 prev_state)
> {
> - const char *str = TASK_STATE_TO_CHAR_STR;
> + const char str[] = TASK_STATE_TO_CHAR_STR;
> + unsigned int bit = prev_state ? __ffs(prev_state) + 1 : 0;
>
> - return str[prev_state];
> + return bit < ARRAY_SIZE(str) - 1 ? str[bit] : '?';
> }
>
> static int
> --
> 2.7.4
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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