Thread (40 messages) 40 messages, 7 authors, 2021-01-01
STALE2012d

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

From: Thomas Gleixner <hidden>
Date: 2020-11-13 14:25:00
Also in: linux-sh, linux-um, lkml

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 <redacted>
---
 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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