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-rw-r--r--debian/patches-rt/0132-tasklets-Replace-barrier-with-cpu_relax-in-tasklet_u.patch35
1 files changed, 35 insertions, 0 deletions
diff --git a/debian/patches-rt/0132-tasklets-Replace-barrier-with-cpu_relax-in-tasklet_u.patch b/debian/patches-rt/0132-tasklets-Replace-barrier-with-cpu_relax-in-tasklet_u.patch
new file mode 100644
index 000000000..8908254e0
--- /dev/null
+++ b/debian/patches-rt/0132-tasklets-Replace-barrier-with-cpu_relax-in-tasklet_u.patch
@@ -0,0 +1,35 @@
+From 8127bb05947dbb12f9537095932d6a7a7a07d09e Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Tue, 9 Mar 2021 09:42:04 +0100
+Subject: [PATCH 132/323] tasklets: Replace barrier() with cpu_relax() in
+ tasklet_unlock_wait()
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.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(-)
+
+diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
+index 0652b4858ba6..fad0eb9d42ab 100644
+--- a/include/linux/interrupt.h
++++ b/include/linux/interrupt.h
+@@ -672,7 +672,8 @@ static inline void tasklet_unlock(struct tasklet_struct *t)
+
+ 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
+--
+2.43.0
+