5.4.74-rt42-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
In patch
("net/Qdisc: use a seqlock instead seqcount")
the seqcount has been replaced with a seqlock to allow to reader to
boost the preempted writer.
The try_write_seqlock() acquired the lock with a try-lock but the
seqcount annotation was "lock".
Opencode write_seqcount_t_begin() and use the try-lock annotation for
lockdep.
Reported-by: Mike Galbraith <efault@xxxxxx>
Cc: stable-rt@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/linux/seqlock.h | 9 ---------
include/net/sch_generic.h | 10 +++++++++-
2 files changed, 9 insertions(+), 10 deletions(-)
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index e5207897c33e..f390293974ea 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -489,15 +489,6 @@ static inline void write_seqlock(seqlock_t *sl)
__raw_write_seqcount_begin(&sl->seqcount);
}
-static inline int try_write_seqlock(seqlock_t *sl)
-{
- if (spin_trylock(&sl->lock)) {
- __raw_write_seqcount_begin(&sl->seqcount);
- return 1;
- }
- return 0;
-}
-
static inline void write_sequnlock(seqlock_t *sl)
{
__raw_write_seqcount_end(&sl->seqcount);
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index e6afb4b9cede..112d2dca8b08 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -168,8 +168,16 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc)
return false;
}
#ifdef CONFIG_PREEMPT_RT
- if (try_write_seqlock(&qdisc->running))
+ if (spin_trylock(&qdisc->running.lock)) {
+ seqcount_t *s = &qdisc->running.seqcount;
+ /*
+ * Variant of write_seqcount_t_begin() telling lockdep that a
+ * trylock was attempted.
+ */
+ __raw_write_seqcount_begin(s);
+ seqcount_acquire(&s->dep_map, 0, 1, _RET_IP_);
return true;
+ }
return false;
#else
/* Variant of write_seqcount_begin() telling lockdep a trylock
--
2.28.0
