From: Peter Zijlstra Date: Tue, 29 Sep 2020 11:33:40 +0000 (+0200) Subject: rcu,ftrace: Fix ftrace recursion X-Git-Tag: howlett/maple_spf/20210104~369^2~2^3~6 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d2098b4440981705e844c50254540ba7b5f82795;p=users%2Fjedix%2Flinux-maple.git rcu,ftrace: Fix ftrace recursion 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 Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5f458e4efc958..d6a015e68649b 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;