The following commit has been merged into the timers/urgent branch of tip:

Commit-ID: 4cd2bb12981165f865d2b8ed92b446b52310ef74 Gitweb: https://git.kernel.org/tip/4cd2bb12981165f865d2b8ed92b446b52310ef74 Author: Quanyang Wang quanyang.wang@windriver.com AuthorDate: Tue, 29 Sep 2020 16:20:27 +08:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Mon, 26 Oct 2020 11:34:31 +01:00

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: 1b86abc1c645 ("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 --- kernel/time/sched_clock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index 0642013..b1b9b12 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -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); }