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tasklets: Provide tasklet_disable_in_atomic()

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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 <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210309084241.563164193@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-03-09 09:42:06 +01:00
parent 6951547a13
commit ca5f625118
1 changed files with 22 additions and 0 deletions
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22
include/linux/interrupt.h
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@ -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);