[v3] rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT

[PATCH v3 1/1] rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT

Posted by Eder Zulian 1 year, 1 month ago

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.")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409251238.vetlgXE9-lkp@intel.com/
Signed-off-by: Eder Zulian <ezulian@redhat.com>
---
V1 -> V2: Cleaned up style and addressed review comments
V2 -> V3: Improved commit title and description and corrected the 'Fixed:'
tag as per reviewer's suggestion

 include/linux/spinlock_rt.h | 15 +++++++--------
 rust/helpers/spinlock.c     |  8 ++++++--
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
index f9f14e135be7..f6499c37157d 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 b7b0945e8b3c..5971fdf6f755 100644
--- a/rust/helpers/spinlock.c
+++ b/rust/helpers/spinlock.c
@@ -6,10 +6,14 @@ 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)
-- 
2.47.0

Re: [PATCH v3 1/1] rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT

Posted by Boqun Feng 1 year, 1 month ago

On Thu, Nov 07, 2024 at 05:32:23PM +0100, Eder Zulian wrote:
> 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.")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202409251238.vetlgXE9-lkp@intel.com/
> Signed-off-by: Eder Zulian <ezulian@redhat.com>

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>

For testing, I used the following command as a reproducer:

ARM64:

./tools/testing/kunit/kunit.py run --make_options LLVM=1 --arch arm64 --kconfig_add CONFIG_RUST=y --kconfig_add CONFIG_SMP=y  rust_doctests_kernel --kconfig_add CONFIG_WERROR=y --kconfig_add CONFIG_EXPERT=y --kconfig_add CONFIG_PREEMPT_RT=y --kconfig_add CONFIG_PROVE_LOCKING=y

X86_64:

./tools/testing/kunit/kunit.py run --make_options LLVM=1 --arch arm64 --kconfig_add CONFIG_RUST=y --kconfig_add CONFIG_SMP=y  rust_doctests_kernel --kconfig_add CONFIG_WERROR=y --kconfig_add CONFIG_EXPERT=y --kconfig_add CONFIG_PREEMPT_RT=y --kconfig_add CONFIG_PROVE_LOCKING=y

And I applied this onto the tip/locking/core, can confirm the build
errors are gone. So

Tested-by: Boqun Feng <boqun.feng@gmail.com>

Regards,
Boqun

> ---
> V1 -> V2: Cleaned up style and addressed review comments
> V2 -> V3: Improved commit title and description and corrected the 'Fixed:'
> tag as per reviewer's suggestion
> 
>  include/linux/spinlock_rt.h | 15 +++++++--------
>  rust/helpers/spinlock.c     |  8 ++++++--
>  2 files changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
> index f9f14e135be7..f6499c37157d 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 b7b0945e8b3c..5971fdf6f755 100644
> --- a/rust/helpers/spinlock.c
> +++ b/rust/helpers/spinlock.c
> @@ -6,10 +6,14 @@ 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)
> -- 
> 2.47.0
>

[tip: locking/core] rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT

Posted by tip-bot2 for Eder Zulian 1 year, 1 month ago

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     5c2e7736e20d9b348a44cafbfa639fe2653fbc34
Gitweb:        https://git.kernel.org/tip/5c2e7736e20d9b348a44cafbfa639fe2653fbc34
Author:        Eder Zulian <ezulian@redhat.com>
AuthorDate:    Thu, 07 Nov 2024 17:32:23 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 11 Nov 2024 11:49:46 +01:00

rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT

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@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Eder Zulian <ezulian@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241107163223.2092690-2-ezulian@redhat.com
---
 include/linux/spinlock_rt.h | 15 +++++++--------
 rust/helpers/spinlock.c     |  8 ++++++--
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
index f9f14e1..f6499c3 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 acc1376..92f7fc4 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)