Messages in this thread Patch in this message | | | Date | Tue, 29 Sep 2020 13:33:40 +0200 | From | Peter Zijlstra <> | Subject | [PATCH] rcu,ftrace: Fix ftrace recursion |
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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. Probably due to there not being a helpful comment.
Reinstate the notrace and add a comment to avoid loosing it again.
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> --- 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 ee5e595501e8..33020d84ec6b 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1098,8 +1098,11 @@ noinstr bool __rcu_is_watching(void) * 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. + * + * Must be notrace because __ftrace_ops_list_func() / ftrace_ops_assist_func() + * will call this (for every function) outside of recursion protection. */ -bool rcu_is_watching(void) +notrace bool rcu_is_watching(void) { bool ret;
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