From 35c080a5db30acfdfa20ca84bf9d0482e6ec1409 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 9 Mar 2021 09:42:06 +0100 Subject: [PATCH 134/323] tasklets: Provide tasklet_disable_in_atomic() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz Replacing the spin wait loops in tasklet_unlock_wait() with wait_var_event() is not possible as a handful of tasklet_disable() invocations are happening in atomic context. All other invocations are in teardown paths which can sleep. Provide tasklet_disable_in_atomic() and tasklet_unlock_spin_wait() to convert the few atomic use cases over, which allows to change tasklet_disable() and tasklet_unlock_wait() in a later step. Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior --- include/linux/interrupt.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 75c4380afe9b..abba3eff4f86 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -675,10 +675,21 @@ static inline void tasklet_unlock_wait(struct tasklet_struct *t) while (test_bit(TASKLET_STATE_RUN, &t->state)) cpu_relax(); } + +/* + * Do not use in new code. Waiting for tasklets from atomic contexts is + * error prone and should be avoided. + */ +static inline void tasklet_unlock_spin_wait(struct tasklet_struct *t) +{ + while (test_bit(TASKLET_STATE_RUN, &t->state)) + cpu_relax(); +} #else static inline int tasklet_trylock(struct tasklet_struct *t) { return 1; } static inline void tasklet_unlock(struct tasklet_struct *t) { } static inline void tasklet_unlock_wait(struct tasklet_struct *t) { } +static inline void tasklet_unlock_spin_wait(struct tasklet_struct *t) { } #endif extern void __tasklet_schedule(struct tasklet_struct *t); @@ -703,6 +714,17 @@ static inline void tasklet_disable_nosync(struct tasklet_struct *t) smp_mb__after_atomic(); } +/* + * Do not use in new code. Disabling tasklets from atomic contexts is + * error prone and should be avoided. + */ +static inline void tasklet_disable_in_atomic(struct tasklet_struct *t) +{ + tasklet_disable_nosync(t); + tasklet_unlock_spin_wait(t); + smp_mb(); +} + static inline void tasklet_disable(struct tasklet_struct *t) { tasklet_disable_nosync(t); -- 2.43.0