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From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 9 Mar 2021 09:42:04 +0100
Subject: [PATCH 01/20] tasklets: Replace barrier() with cpu_relax() in
tasklet_unlock_wait()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.21-rt34.tar.xz
A barrier() in a tight loop which waits for something to happen on a remote
CPU is a pointless exercise. Replace it with cpu_relax() which allows HT
siblings to make progress.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/interrupt.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -668,7 +668,8 @@ static inline void tasklet_unlock(struct
static inline void tasklet_unlock_wait(struct tasklet_struct *t)
{
- while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); }
+ while (test_bit(TASKLET_STATE_RUN, &t->state))
+ cpu_relax();
}
#else
#define tasklet_trylock(t) 1
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