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@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202409251238.vetlgXE9-lkp@xxxxxxxxx/
> Signed-off-by: Eder Zulian <ezulian@xxxxxxxxxx>
Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>
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@xxxxxxxxx>
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
>
