diff options
| 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 /include | |
| parent | 04fabf00b4d3aff5d010ecb617001814e409e24a (diff) | |
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')
| -rw-r--r-- | include/linux/rcutiny.h | 2 | ||||
| -rw-r--r-- | include/linux/rcutree.h | 1 |
2 files changed, 3 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. diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 56bccb5a8fde..126f6b418f6a 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -21,6 +21,7 @@ void rcu_softirq_qs(void); void rcu_note_context_switch(bool preempt); int rcu_needs_cpu(void); void rcu_cpu_stall_reset(void); +void rcu_request_urgent_qs_task(struct task_struct *t); /* * Note a virtualization-based context switch. This is simply a |