diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2022-03-04 10:41:44 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-04-11 17:06:42 -0700 |
| commit | 5d90070816534882b9158f14154b7e2cdef1194a (patch) | |
| tree | ff57ad59d100eaba92b197926d88ca504378df30 | |
| parent | 88db792bbe9b140680c74e9f2f801ac00f54e05e (diff) | |
rcu-tasks: Make Tasks RCU account for userspace execution
The main Tasks RCU quiescent state is voluntary context switch. However,
userspace execution is also a valid quiescent state, and is a valuable one
for userspace applications that spin repeatedly executing light-weight
non-sleeping system calls. Currently, such an application can delay a
Tasks RCU grace period for many tens of seconds.
This commit therefore enlists the aid of the scheduler-clock interrupt to
provide a Tasks RCU quiescent state when it interrupted a task executing
in userspace.
[ paulmck: Apply feedback from kernel test robot. ]
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Neil Spring <ntspring@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | include/linux/rcupdate.h | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 2 |
2 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index e7c39c200e2b..1a32036c918c 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -196,6 +196,7 @@ void synchronize_rcu_tasks_rude(void); void exit_tasks_rcu_start(void); void exit_tasks_rcu_finish(void); #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */ +#define rcu_tasks_classic_qs(t, preempt) do { } while (0) #define rcu_tasks_qs(t, preempt) do { } while (0) #define rcu_note_voluntary_context_switch(t) do { } while (0) #define call_rcu_tasks call_rcu diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a4b8189455d5..8dbfb63f0391 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2624,6 +2624,8 @@ void rcu_sched_clock_irq(int user) rcu_flavor_sched_clock_irq(user); if (rcu_pending(user)) invoke_rcu_core(); + if (user) + rcu_tasks_classic_qs(current, false); lockdep_assert_irqs_disabled(); trace_rcu_utilization(TPS("End scheduler-tick")); |