Messages in this thread | | | Date | Tue, 29 Sep 2020 07:31:46 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] rcu,ftrace: Fix ftrace recursion |
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On Tue, Sep 29, 2020 at 01:33:40PM +0200, Peter Zijlstra wrote: > > 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.
s/loosing/losing/, but otherwise:
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
But please let me know if you would prefer that I take it via -rcu.
Thanx, Paul
> 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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