From 43a89baecfe200cb4530f42b9fcf904925d6d14a Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 5 Jul 2023 20:34:43 -0700 Subject: rcu: Export rcu_request_urgent_qs_task() If a CPU is executing a long series of non-sleeping system calls, RCU grace periods can be delayed for on the order of a couple hundred milliseconds. This is normally not a problem, but if each system call does a call_rcu(), those callbacks can stack up. RCU will eventually notice this callback storm, but use of rcu_request_urgent_qs_task() allows the code invoking call_rcu() to give RCU a heads up. This function is not for general use, not yet, anyway. Reported-by: Alexei Starovoitov Signed-off-by: Paul E. McKenney Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20230706033447.54696-11-alexei.starovoitov@gmail.com --- include/linux/rcutiny.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/rcutiny.h') diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 7f17acf29dda..7b949292908a 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -138,6 +138,8 @@ static inline int rcu_needs_cpu(void) return 0; } +static inline void rcu_request_urgent_qs_task(struct task_struct *t) { } + /* * Take advantage of the fact that there is only one CPU, which * allows us to ignore virtualization-based context switches. -- cgit v1.2.3-73-gaa49b