This patch adds the __cond_lock() macro to refcounts conditional lock API. Currently sparse cannot detect the conditional lock handling of refcount_dec_and_lock() functionality and prints a context imbalance warning like: warning: context imbalance in 'put_rsb' - unexpected unlock with this patch and having the refcount_dec_and_lock() functionality inside the if condition to decide whenever doing unlock or not the warning disappears. The patch follows a similar naming scheme like raw_spin_trylock() by adding a "raw_" prefix to refcount_dec_and_lock() functionality and introduce a macro for the replaced functions that uses __cond_lock() to signal that an acquire depends on the return value of the passed function. A cast to bool seems to be necessary because __cond_lock() does return a non-boolean scalar type. The __must_check annotation was tested and is still working with this patch applied. Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx> --- include/linux/refcount.h | 21 ++++++++++++++++----- lib/refcount.c | 23 ++++++++++++----------- 2 files changed, 28 insertions(+), 16 deletions(-) diff --git a/include/linux/refcount.h b/include/linux/refcount.h index b8a6e387f8f9..be7b970ce475 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -361,9 +361,20 @@ static inline void refcount_dec(refcount_t *r) extern __must_check bool refcount_dec_if_one(refcount_t *r); extern __must_check bool refcount_dec_not_one(refcount_t *r); -extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock); -extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock); -extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r, - spinlock_t *lock, - unsigned long *flags); +extern __must_check bool raw_refcount_dec_and_mutex_lock(refcount_t *r, + struct mutex *lock); +#define refcount_dec_and_mutex_lock(r, lock) \ + ((bool)(__cond_lock(lock, raw_refcount_dec_and_mutex_lock(r, lock)))) + +extern __must_check bool raw_refcount_dec_and_lock(refcount_t *r, + spinlock_t *lock); +#define refcount_dec_and_lock(r, lock) \ + ((bool)(__cond_lock(lock, raw_refcount_dec_and_lock(r, lock)))) + +extern __must_check bool raw_refcount_dec_and_lock_irqsave(refcount_t *r, + spinlock_t *lock, + unsigned long *flags); +#define refcount_dec_and_lock_irqsave(r, lock, flags) \ + ((bool)(__cond_lock(lock, raw_refcount_dec_and_lock_irqsave(r, lock, flags)))) + #endif /* _LINUX_REFCOUNT_H */ diff --git a/lib/refcount.c b/lib/refcount.c index a207a8f22b3c..1a8c7b9aba23 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -110,7 +110,7 @@ EXPORT_SYMBOL(refcount_dec_not_one); * Return: true and hold mutex if able to decrement refcount to 0, false * otherwise */ -bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) +bool raw_refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) { if (refcount_dec_not_one(r)) return false; @@ -123,11 +123,11 @@ bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) return true; } -EXPORT_SYMBOL(refcount_dec_and_mutex_lock); +EXPORT_SYMBOL(raw_refcount_dec_and_mutex_lock); /** - * refcount_dec_and_lock - return holding spinlock if able to decrement - * refcount to 0 + * raw_refcount_dec_and_lock - return holding spinlock if able to decrement + * refcount to 0 * @r: the refcount * @lock: the spinlock to be locked * @@ -141,7 +141,7 @@ EXPORT_SYMBOL(refcount_dec_and_mutex_lock); * Return: true and hold spinlock if able to decrement refcount to 0, false * otherwise */ -bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) +bool raw_refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) { if (refcount_dec_not_one(r)) return false; @@ -154,11 +154,12 @@ bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) return true; } -EXPORT_SYMBOL(refcount_dec_and_lock); +EXPORT_SYMBOL(raw_refcount_dec_and_lock); /** - * refcount_dec_and_lock_irqsave - return holding spinlock with disabled - * interrupts if able to decrement refcount to 0 + * raw_refcount_dec_and_lock_irqsave - return holding spinlock with disabled + * interrupts if able to decrement + * refcount to 0 * @r: the refcount * @lock: the spinlock to be locked * @flags: saved IRQ-flags if the is acquired @@ -169,8 +170,8 @@ EXPORT_SYMBOL(refcount_dec_and_lock); * Return: true and hold spinlock if able to decrement refcount to 0, false * otherwise */ -bool refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, - unsigned long *flags) +bool raw_refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, + unsigned long *flags) { if (refcount_dec_not_one(r)) return false; @@ -183,4 +184,4 @@ bool refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, return true; } -EXPORT_SYMBOL(refcount_dec_and_lock_irqsave); +EXPORT_SYMBOL(raw_refcount_dec_and_lock_irqsave); -- 2.31.1