6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra peterz@infradead.org
[ Upstream commit e4ab322fbaaaf84b23d6cb0e3317a7f68baf36dc ]
Adds:
- DEFINE_GUARD_COND() / DEFINE_LOCK_GUARD_1_COND() to extend existing guards with conditional lock primitives, eg. mutex_trylock(), mutex_lock_interruptible().
nb. both primitives allow NULL 'locks', which cause the lock to fail (obviously).
- extends scoped_guard() to not take the body when the the conditional guard 'fails'. eg.
scoped_guard (mutex_intr, &task->signal_cred_guard_mutex) { ... }
will only execute the body when the mutex is held.
- provides scoped_cond_guard(name, fail, args...); which extends scoped_guard() to do fail when the lock-acquire fails.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20231102110706.460851167%40infradead.org Stable-dep-of: fcc22ac5baf0 ("cleanup: Adjust scoped_guard() macros to avoid potential warning") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/cleanup.h | 52 +++++++++++++++++++++++++++++++++++++--- include/linux/mutex.h | 3 ++- include/linux/rwsem.h | 8 +++---- include/linux/spinlock.h | 15 ++++++++++++ 4 files changed, 70 insertions(+), 8 deletions(-)
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h index 53f1a7a932b0..6d7bfa899df0 100644 --- a/include/linux/cleanup.h +++ b/include/linux/cleanup.h @@ -92,25 +92,55 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ * trivial wrapper around DEFINE_CLASS() above specifically * for locks. * + * DEFINE_GUARD_COND(name, ext, condlock) + * wrapper around EXTEND_CLASS above to add conditional lock + * variants to a base class, eg. mutex_trylock() or + * mutex_lock_interruptible(). + * * guard(name): - * an anonymous instance of the (guard) class + * an anonymous instance of the (guard) class, not recommended for + * conditional locks. * * scoped_guard (name, args...) { }: * similar to CLASS(name, scope)(args), except the variable (with the * explicit name 'scope') is declard in a for-loop such that its scope is * bound to the next (compound) statement. * + * for conditional locks the loop body is skipped when the lock is not + * acquired. + * + * scoped_cond_guard (name, fail, args...) { }: + * similar to scoped_guard(), except it does fail when the lock + * acquire fails. + * */
#define DEFINE_GUARD(_name, _type, _lock, _unlock) \ - DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T) + DEFINE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type _T); \ + static inline void * class_##_name##_lock_ptr(class_##_name##_t *_T) \ + { return *_T; } + +#define DEFINE_GUARD_COND(_name, _ext, _condlock) \ + EXTEND_CLASS(_name, _ext, \ + ({ void *_t = _T; if (_T && !(_condlock)) _t = NULL; _t; }), \ + class_##_name##_t _T) \ + static inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T) \ + { return class_##_name##_lock_ptr(_T); }
#define guard(_name) \ CLASS(_name, __UNIQUE_ID(guard))
+#define __guard_ptr(_name) class_##_name##_lock_ptr + #define scoped_guard(_name, args...) \ for (CLASS(_name, scope)(args), \ - *done = NULL; !done; done = (void *)1) + *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1) + +#define scoped_cond_guard(_name, _fail, args...) \ + for (CLASS(_name, scope)(args), \ + *done = NULL; !done; done = (void *)1) \ + if (!__guard_ptr(_name)(&scope)) _fail; \ + else
/* * Additional helper macros for generating lock guards with types, either for @@ -119,6 +149,7 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ * * DEFINE_LOCK_GUARD_0(name, lock, unlock, ...) * DEFINE_LOCK_GUARD_1(name, type, lock, unlock, ...) + * DEFINE_LOCK_GUARD_1_COND(name, ext, condlock) * * will result in the following type: * @@ -140,6 +171,11 @@ typedef struct { \ static inline void class_##_name##_destructor(class_##_name##_t *_T) \ { \ if (_T->lock) { _unlock; } \ +} \ + \ +static inline void *class_##_name##_lock_ptr(class_##_name##_t *_T) \ +{ \ + return _T->lock; \ }
@@ -168,4 +204,14 @@ __DEFINE_LOCK_GUARD_1(_name, _type, _lock) __DEFINE_UNLOCK_GUARD(_name, void, _unlock, __VA_ARGS__) \ __DEFINE_LOCK_GUARD_0(_name, _lock)
+#define DEFINE_LOCK_GUARD_1_COND(_name, _ext, _condlock) \ + EXTEND_CLASS(_name, _ext, \ + ({ class_##_name##_t _t = { .lock = l }, *_T = &_t;\ + if (_T->lock && !(_condlock)) _T->lock = NULL; \ + _t; }), \ + typeof_member(class_##_name##_t, lock) l) \ + static inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T) \ + { return class_##_name##_lock_ptr(_T); } + + #endif /* __LINUX_GUARDS_H */ diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 5b5630e58407..e1c323c7d75b 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -248,6 +248,7 @@ extern void mutex_unlock(struct mutex *lock); extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T)) -DEFINE_FREE(mutex, struct mutex *, if (_T) mutex_unlock(_T)) +DEFINE_GUARD_COND(mutex, _try, mutex_trylock(_T)) +DEFINE_GUARD_COND(mutex, _intr, mutex_lock_interruptible(_T) == 0)
#endif /* __LINUX_MUTEX_H */ diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 1dd530ce8b45..9c29689ff505 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -203,11 +203,11 @@ extern void up_read(struct rw_semaphore *sem); extern void up_write(struct rw_semaphore *sem);
DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T)) -DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T)) - -DEFINE_FREE(up_read, struct rw_semaphore *, if (_T) up_read(_T)) -DEFINE_FREE(up_write, struct rw_semaphore *, if (_T) up_write(_T)) +DEFINE_GUARD_COND(rwsem_read, _try, down_read_trylock(_T)) +DEFINE_GUARD_COND(rwsem_read, _intr, down_read_interruptible(_T) == 0)
+DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T)) +DEFINE_GUARD_COND(rwsem_write, _try, down_write_trylock(_T))
/* * downgrade write lock to read lock diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 31d3d747a9db..ceb56b39c70f 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -507,6 +507,8 @@ DEFINE_LOCK_GUARD_1(raw_spinlock, raw_spinlock_t, raw_spin_lock(_T->lock), raw_spin_unlock(_T->lock))
+DEFINE_LOCK_GUARD_1_COND(raw_spinlock, _try, raw_spin_trylock(_T->lock)) + DEFINE_LOCK_GUARD_1(raw_spinlock_nested, raw_spinlock_t, raw_spin_lock_nested(_T->lock, SINGLE_DEPTH_NESTING), raw_spin_unlock(_T->lock)) @@ -515,23 +517,36 @@ DEFINE_LOCK_GUARD_1(raw_spinlock_irq, raw_spinlock_t, raw_spin_lock_irq(_T->lock), raw_spin_unlock_irq(_T->lock))
+DEFINE_LOCK_GUARD_1_COND(raw_spinlock_irq, _try, raw_spin_trylock_irq(_T->lock)) + DEFINE_LOCK_GUARD_1(raw_spinlock_irqsave, raw_spinlock_t, raw_spin_lock_irqsave(_T->lock, _T->flags), raw_spin_unlock_irqrestore(_T->lock, _T->flags), unsigned long flags)
+DEFINE_LOCK_GUARD_1_COND(raw_spinlock_irqsave, _try, + raw_spin_trylock_irqsave(_T->lock, _T->flags)) + DEFINE_LOCK_GUARD_1(spinlock, spinlock_t, spin_lock(_T->lock), spin_unlock(_T->lock))
+DEFINE_LOCK_GUARD_1_COND(spinlock, _try, spin_trylock(_T->lock)) + DEFINE_LOCK_GUARD_1(spinlock_irq, spinlock_t, spin_lock_irq(_T->lock), spin_unlock_irq(_T->lock))
+DEFINE_LOCK_GUARD_1_COND(spinlock_irq, _try, + spin_trylock_irq(_T->lock)) + DEFINE_LOCK_GUARD_1(spinlock_irqsave, spinlock_t, spin_lock_irqsave(_T->lock, _T->flags), spin_unlock_irqrestore(_T->lock, _T->flags), unsigned long flags)
+DEFINE_LOCK_GUARD_1_COND(spinlock_irqsave, _try, + spin_trylock_irqsave(_T->lock, _T->flags)) + #undef __LINUX_INSIDE_SPINLOCK_H #endif /* __LINUX_SPINLOCK_H */