From: <quanyang.wang@windriver.com>
To: <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Leo Yan <leo.yan@linaro.org>, Will Deacon <will@kernel.org>,
<a.darwish@linutronix.de>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Paul Cercueil <paul@crapouillou.net>,
Randy Dunlap <rdunlap@infradead.org>, <ben.dooks@codethink.co.uk>
Subject: [PATCH V3] time/sched_clock: mark sched_clock_read_begin/retry as notrace
Date: Tue, 29 Sep 2020 16:20:27 +0800 [thread overview]
Message-ID: <20200929082027.16787-1-quanyang.wang@windriver.com> (raw)
From: Quanyang Wang <quanyang.wang@windriver.com>
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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
Changes:
V2: Add notrace to sched_clock_read_retry according to Peter's suggestion.
V3: Adjust the placement of notrace according to Peter's suggestion.
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 1c03eec6ca9b..f629e3f5afbe 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_retry(&cd.seq, seq);
}
--
2.17.1
next reply other threads:[~2020-09-29 8:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 8:20 quanyang.wang [this message]
2020-10-26 10:40 ` [tip: timers/urgent] time/sched_clock: Mark sched_clock_read_begin/retry() as notrace tip-bot2 for Quanyang Wang
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