From 33f137143e651321f10eb67ae6404a13bfbf69f8 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 1 May 2024 16:12:37 -0700 Subject: [PATCH] ftrace: Use asynchronous grace period for register_ftrace_direct() When running heavy test workloads with KASAN enabled, RCU Tasks grace periods can extend for many tens of seconds, significantly slowing trace registration. Therefore, make the registration-side RCU Tasks grace period be asynchronous via call_rcu_tasks(). Link: https://lore.kernel.org/linux-trace-kernel/ac05be77-2972-475b-9b57-56bef15aa00a@paulmck-laptop Reported-by: Jakub Kicinski Reported-by: Alexei Starovoitov Reported-by: Chris Mason Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Paul E. McKenney Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 3951c0d0ec631..f9223513414a3 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5366,6 +5366,13 @@ static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long } } +static void register_ftrace_direct_cb(struct rcu_head *rhp) +{ + struct ftrace_hash *fhp = container_of(rhp, struct ftrace_hash, rcu); + + free_ftrace_hash(fhp); +} + /** * register_ftrace_direct - Call a custom trampoline directly * for multiple functions registered in @ops @@ -5464,10 +5471,8 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) out_unlock: mutex_unlock(&direct_mutex); - if (free_hash && free_hash != EMPTY_HASH) { - synchronize_rcu_tasks(); - free_ftrace_hash(free_hash); - } + if (free_hash && free_hash != EMPTY_HASH) + call_rcu_tasks(&free_hash->rcu, register_ftrace_direct_cb); if (new_hash) free_ftrace_hash(new_hash); -- 2.30.2