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authorPaul E. McKenney <paulmck@kernel.org>2023-07-06 06:34:43 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2023-07-13 00:45:23 +0300
commit43a89baecfe200cb4530f42b9fcf904925d6d14a (patch)
tree49f4959bd244b9885cb585e1663cce7988cf334d /include/linux/rcutiny.h
parent04fabf00b4d3aff5d010ecb617001814e409e24a (diff)
downloadlinux-43a89baecfe200cb4530f42b9fcf904925d6d14a.tar.xz
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 <ast@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20230706033447.54696-11-alexei.starovoitov@gmail.com
Diffstat (limited to 'include/linux/rcutiny.h')
-rw-r--r--include/linux/rcutiny.h2
1 files changed, 2 insertions, 0 deletions
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.