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| author | Paul E. McKenney <paulmck@kernel.org> | 2023-07-05 20:34:43 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-07-12 23:45:23 +0200 |
| commit | 43a89baecfe200cb4530f42b9fcf904925d6d14a (patch) | |
| tree | 49f4959bd244b9885cb585e1663cce7988cf334d /kernel/rcu/rcu.h | |
| parent | 04fabf00b4d3aff5d010ecb617001814e409e24a (diff) | |
| download | linux-43a89baecfe200cb4530f42b9fcf904925d6d14a.tar.gz linux-43a89baecfe200cb4530f42b9fcf904925d6d14a.tar.bz2 linux-43a89baecfe200cb4530f42b9fcf904925d6d14a.zip | |
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 'kernel/rcu/rcu.h')
| -rw-r--r-- | kernel/rcu/rcu.h | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 98c1544cf572..f95cfb5bf2ee 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -493,7 +493,6 @@ static inline void rcu_expedite_gp(void) { } static inline void rcu_unexpedite_gp(void) { } static inline void rcu_async_hurry(void) { } static inline void rcu_async_relax(void) { } -static inline void rcu_request_urgent_qs_task(struct task_struct *t) { } #else /* #ifdef CONFIG_TINY_RCU */ bool rcu_gp_is_normal(void); /* Internal RCU use. */ bool rcu_gp_is_expedited(void); /* Internal RCU use. */ @@ -508,7 +507,6 @@ void show_rcu_tasks_gp_kthreads(void); #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */ static inline void show_rcu_tasks_gp_kthreads(void) {} #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */ -void rcu_request_urgent_qs_task(struct task_struct *t); #endif /* #else #ifdef CONFIG_TINY_RCU */ #define RCU_SCHEDULER_INACTIVE 0 |