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Message-ID: <20240925053405.3960701-8-neilb@suse.de>
Date: Wed, 25 Sep 2024 15:31:44 +1000
From: NeilBrown <neilb@...e.de>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 7/7] softirq: use bit waits instead of var waits.
The waiting in softirq.c is always waiting for a bit to be cleared.
This makes the bit wait functions seem more suitable.
By switching over we can rid of all explicit barriers. We also use
wait_on_bit_lock() to avoid an explicit loop.
Signed-off-by: NeilBrown <neilb@...e.de>
---
kernel/softirq.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index d082e7840f88..b756d6b3fd09 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -748,10 +748,8 @@ EXPORT_SYMBOL(__tasklet_hi_schedule);
static bool tasklet_clear_sched(struct tasklet_struct *t)
{
- if (test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) {
- wake_up_var(&t->state);
+ if (test_and_clear_wake_up_bit(TASKLET_STATE_SCHED, &t->state))
return true;
- }
WARN_ONCE(1, "tasklet SCHED state not set: %s %pS\n",
t->use_callback ? "callback" : "func",
@@ -871,8 +869,7 @@ void tasklet_kill(struct tasklet_struct *t)
if (in_interrupt())
pr_notice("Attempt to kill tasklet from interrupt\n");
- while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
- wait_var_event(&t->state, !test_bit(TASKLET_STATE_SCHED, &t->state));
+ wait_on_bit_lock(&t->state, TASKLET_STATE_SCHED, TASK_UNINTERRUPTIBLE);
tasklet_unlock_wait(t);
tasklet_clear_sched(t);
@@ -882,16 +879,13 @@ EXPORT_SYMBOL(tasklet_kill);
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
void tasklet_unlock(struct tasklet_struct *t)
{
- smp_mb__before_atomic();
- clear_bit(TASKLET_STATE_RUN, &t->state);
- smp_mb__after_atomic();
- wake_up_var(&t->state);
+ clear_and_wake_up_bit(TASKLET_STATE_RUN, &t->state);
}
EXPORT_SYMBOL_GPL(tasklet_unlock);
void tasklet_unlock_wait(struct tasklet_struct *t)
{
- wait_var_event(&t->state, !test_bit(TASKLET_STATE_RUN, &t->state));
+ wait_on_bit(&t->state, TASKLET_STATE_RUN, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL_GPL(tasklet_unlock_wait);
#endif
--
2.46.0
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