On Fri, 19 Apr 2024 10:59:09 -0700 Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > On Thu, Apr 18, 2024 at 6:00 PM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > > > On Thu, 18 Apr 2024 12:09:09 -0700 > > Andrii Nakryiko <andrii@xxxxxxxxxx> wrote: > > > > > Take into account CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING when validating > > > that RCU is watching when trying to setup rethooko on a function entry. > > > > > > One notable exception when we force rcu_is_watching() check is > > > CONFIG_KPROBE_EVENTS_ON_NOTRACE=y case, in which case kretprobes will use > > > old-style int3-based workflow instead of relying on ftrace, making RCU > > > watching check important to validate. > > > > > > This further (in addition to improvements in the previous patch) > > > improves BPF multi-kretprobe (which rely on rethook) runtime throughput > > > by 2.3%, according to BPF benchmarks ([0]). > > > > > > [0] https://lore.kernel.org/bpf/CAEf4BzauQ2WKMjZdc9s0rBWa01BYbgwHN6aNDXQSHYia47pQ-w@xxxxxxxxxxxxxx/ > > > > > > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > > > > > Thanks for update! This looks good to me. > > Thanks, Masami! Will you take it through your tree, or you'd like to > route it through bpf-next? OK, let me take it through linux-trace tree. Thank you! > > > > > Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> > > > > Thanks, > > > > > --- > > > kernel/trace/rethook.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c > > > index fa03094e9e69..a974605ad7a5 100644 > > > --- a/kernel/trace/rethook.c > > > +++ b/kernel/trace/rethook.c > > > @@ -166,6 +166,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > > > if (unlikely(!handler)) > > > return NULL; > > > > > > +#if defined(CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING) || defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE) > > > /* > > > * This expects the caller will set up a rethook on a function entry. > > > * When the function returns, the rethook will eventually be reclaimed > > > @@ -174,6 +175,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > > > */ > > > if (unlikely(!rcu_is_watching())) > > > return NULL; > > > +#endif > > > > > > return (struct rethook_node *)objpool_pop(&rh->pool); > > > } > > > -- > > > 2.43.0 > > > > > > > > > -- > > Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> -- Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
