[patch 17/19] softirq: Replace barrier() with cpu_relax() in tasklet_unlock_wait()

From: Thomas Gleixner
Date: Fri Nov 13 2020 - 09:25:00 EST


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@xxxxxxxxxxxxx>
---
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