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-rw-r--r--debian/patches-rt/0134-tasklets-Provide-tasklet_disable_in_atomic.patch68
1 files changed, 68 insertions, 0 deletions
diff --git a/debian/patches-rt/0134-tasklets-Provide-tasklet_disable_in_atomic.patch b/debian/patches-rt/0134-tasklets-Provide-tasklet_disable_in_atomic.patch
new file mode 100644
index 000000000..2f6fb1ab9
--- /dev/null
+++ b/debian/patches-rt/0134-tasklets-Provide-tasklet_disable_in_atomic.patch
@@ -0,0 +1,68 @@
+From 35c080a5db30acfdfa20ca84bf9d0482e6ec1409 Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Tue, 9 Mar 2021 09:42:06 +0100
+Subject: [PATCH 134/323] tasklets: Provide tasklet_disable_in_atomic()
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+Replacing the spin wait loops in tasklet_unlock_wait() with
+wait_var_event() is not possible as a handful of tasklet_disable()
+invocations are happening in atomic context. All other invocations are in
+teardown paths which can sleep.
+
+Provide tasklet_disable_in_atomic() and tasklet_unlock_spin_wait() to
+convert the few atomic use cases over, which allows to change
+tasklet_disable() and tasklet_unlock_wait() in a later step.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ include/linux/interrupt.h | 22 ++++++++++++++++++++++
+ 1 file changed, 22 insertions(+)
+
+diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
+index 75c4380afe9b..abba3eff4f86 100644
+--- a/include/linux/interrupt.h
++++ b/include/linux/interrupt.h
+@@ -675,10 +675,21 @@ static inline void tasklet_unlock_wait(struct tasklet_struct *t)
+ while (test_bit(TASKLET_STATE_RUN, &t->state))
+ cpu_relax();
+ }
++
++/*
++ * Do not use in new code. Waiting for tasklets from atomic contexts is
++ * error prone and should be avoided.
++ */
++static inline void tasklet_unlock_spin_wait(struct tasklet_struct *t)
++{
++ while (test_bit(TASKLET_STATE_RUN, &t->state))
++ cpu_relax();
++}
+ #else
+ static inline int tasklet_trylock(struct tasklet_struct *t) { return 1; }
+ static inline void tasklet_unlock(struct tasklet_struct *t) { }
+ static inline void tasklet_unlock_wait(struct tasklet_struct *t) { }
++static inline void tasklet_unlock_spin_wait(struct tasklet_struct *t) { }
+ #endif
+
+ extern void __tasklet_schedule(struct tasklet_struct *t);
+@@ -703,6 +714,17 @@ static inline void tasklet_disable_nosync(struct tasklet_struct *t)
+ smp_mb__after_atomic();
+ }
+
++/*
++ * Do not use in new code. Disabling tasklets from atomic contexts is
++ * error prone and should be avoided.
++ */
++static inline void tasklet_disable_in_atomic(struct tasklet_struct *t)
++{
++ tasklet_disable_nosync(t);
++ tasklet_unlock_spin_wait(t);
++ smp_mb();
++}
++
+ static inline void tasklet_disable(struct tasklet_struct *t)
+ {
+ tasklet_disable_nosync(t);
+--
+2.43.0
+