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time/sched_clock: Mark sched_clock_read_begin/retry() as notrace 

Since sched_clock_read_begin() and sched_clock_read_retry() are called
by notrace function sched_clock(), they shouldn't be traceable either,
or else ftrace_graph_caller will run into a dead loop on the path
as below (arm for instance):

  ftrace_graph_caller()
    prepare_ftrace_return()
      function_graph_enter()
        ftrace_push_return_trace()
          trace_clock_local()
            sched_clock()
              sched_clock_read_begin/retry()

Fixes: 1b86abc1c6 ("sched_clock: Expose struct clock_read_data")
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200929082027.16787-1-quanyang.wang@windriver.com
pull/193/head
Quanyang Wang 2020-09-29 16:20:27 +08:00 committed by Thomas Gleixner
parent 3650b228f8
commit 4cd2bb1298
1 changed files with 2 additions and 2 deletions
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4
kernel/time/sched_clock.c
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@ -68,13 +68,13 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
return (cyc * mult) >> shift;
}
struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
notrace struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
{
*seq = raw_read_seqcount_latch(&cd.seq);
return cd.read_data + (*seq & 1);
}
int sched_clock_read_retry(unsigned int seq)
notrace int sched_clock_read_retry(unsigned int seq)
{
return read_seqcount_latch_retry(&cd.seq, seq);
}