Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 168/717] rcu,ftrace: Fix ftrace recursion | Date | Mon, 28 Dec 2020 13:42:46 +0100 |
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From: Peter Zijlstra <peterz@infradead.org>
[ Upstream commit d2098b4440981705e844c50254540ba7b5f82795 ]
Kim reported that perf-ftrace made his box unhappy. It turns out that commit:
ff5c4f5cad33 ("rcu/tree: Mark the idle relevant functions noinstr")
removed one too many notrace qualifiers, probably due to there not being a helpful comment.
This commit therefore reinstates the notrace and adds a comment to avoid losing it again.
[ paulmck: Apply Steven Rostedt's feedback on the comment. ] Fixes: ff5c4f5cad33 ("rcu/tree: Mark the idle relevant functions noinstr") Reported-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- kernel/rcu/tree.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 655ade095e043..585bf112ee08d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1093,8 +1093,11 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp) * CPU can safely enter RCU read-side critical sections. In other words, * if the current CPU is not in its idle loop or is in an interrupt or * NMI handler, return true. + * + * Make notrace because it can be called by the internal functions of + * ftrace, and making this notrace removes unnecessary recursion calls. */ -bool rcu_is_watching(void) +notrace bool rcu_is_watching(void) { bool ret; -- 2.27.0
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