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[01/14] tasklets: Replace barrier() with cpu_relax() in tasklet_unlock_wait()

Message ID 20210309084241.249343366@linutronix.de
State New
Headers show
Series tasklets: Replace the spin wait loops and make it RT safe | expand

Commit Message

Thomas Gleixner March 9, 2021, 8:42 a.m. UTC
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>
 include/linux/interrupt.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -672,7 +672,8 @@  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();
 #define tasklet_trylock(t) 1