This is a note to let you know that I've just added the patch titled
rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT
to the 6.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rust-helpers-avoid-raw_spin_lock-initialization-for-.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 772f88a6aaed73739bcec1cb3519989732e491ec
Author: Eder Zulian <ezulian@xxxxxxxxxx>
Date: Thu Nov 7 17:32:23 2024 +0100
rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT
[ Upstream commit 5c2e7736e20d9b348a44cafbfa639fe2653fbc34 ]
When PREEMPT_RT=y, spin locks are mapped to rt_mutex types, so using
spinlock_check() + __raw_spin_lock_init() to initialize spin locks is
incorrect, and would cause build errors.
Introduce __spin_lock_init() to initialize a spin lock with lockdep
rquired information for PREEMPT_RT builds, and use it in the Rust
helper.
Fixes: d2d6422f8bd1 ("x86: Allow to enable PREEMPT_RT.")
Closes: https://lore.kernel.org/oe-kbuild-all/202409251238.vetlgXE9-lkp@xxxxxxxxx/
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Eder Zulian <ezulian@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Tested-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Link: https://lore.kernel.org/r/20241107163223.2092690-2-ezulian@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
index babc3e0287791..6175cd682ca0d 100644
--- a/include/linux/spinlock_rt.h
+++ b/include/linux/spinlock_rt.h
@@ -16,22 +16,21 @@ static inline void __rt_spin_lock_init(spinlock_t *lock, const char *name,
}
#endif
-#define spin_lock_init(slock) \
+#define __spin_lock_init(slock, name, key, percpu) \
do { \
- static struct lock_class_key __key; \
- \
rt_mutex_base_init(&(slock)->lock); \
- __rt_spin_lock_init(slock, #slock, &__key, false); \
+ __rt_spin_lock_init(slock, name, key, percpu); \
} while (0)
-#define local_spin_lock_init(slock) \
+#define _spin_lock_init(slock, percpu) \
do { \
static struct lock_class_key __key; \
- \
- rt_mutex_base_init(&(slock)->lock); \
- __rt_spin_lock_init(slock, #slock, &__key, true); \
+ __spin_lock_init(slock, #slock, &__key, percpu); \
} while (0)
+#define spin_lock_init(slock) _spin_lock_init(slock, false)
+#define local_spin_lock_init(slock) _spin_lock_init(slock, true)
+
extern void rt_spin_lock(spinlock_t *lock) __acquires(lock);
extern void rt_spin_lock_nested(spinlock_t *lock, int subclass) __acquires(lock);
extern void rt_spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *nest_lock) __acquires(lock);
diff --git a/rust/helpers/spinlock.c b/rust/helpers/spinlock.c
index acc1376b833c7..92f7fc4184253 100644
--- a/rust/helpers/spinlock.c
+++ b/rust/helpers/spinlock.c
@@ -7,10 +7,14 @@ void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
struct lock_class_key *key)
{
#ifdef CONFIG_DEBUG_SPINLOCK
+# if defined(CONFIG_PREEMPT_RT)
+ __spin_lock_init(lock, name, key, false);
+# else /*!CONFIG_PREEMPT_RT */
__raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
-#else
+# endif /* CONFIG_PREEMPT_RT */
+#else /* !CONFIG_DEBUG_SPINLOCK */
spin_lock_init(lock);
-#endif
+#endif /* CONFIG_DEBUG_SPINLOCK */
}
void rust_helper_spin_lock(spinlock_t *lock)
