Add support for Clang's capability analysis for rw_semaphore. Signed-off-by: Marco Elver --- v3: * Switch to DECLARE_LOCK_GUARD_1_ATTRS() (suggested by Peter) * __assert -> __assume rename --- .../dev-tools/capability-analysis.rst | 2 +- include/linux/rwsem.h | 66 ++++++++++++------- lib/test_capability-analysis.c | 64 ++++++++++++++++++ 3 files changed, 106 insertions(+), 26 deletions(-) diff --git a/Documentation/dev-tools/capability-analysis.rst b/Documentation/dev-tools/capability-analysis.rst index 779ecb5ec17a..7a4c2238c910 100644 --- a/Documentation/dev-tools/capability-analysis.rst +++ b/Documentation/dev-tools/capability-analysis.rst @@ -82,7 +82,7 @@ Supported Kernel Primitives Currently the following synchronization primitives are supported: `raw_spinlock_t`, `spinlock_t`, `rwlock_t`, `mutex`, `seqlock_t`, -`bit_spinlock`, RCU, SRCU (`srcu_struct`). +`bit_spinlock`, RCU, SRCU (`srcu_struct`), `rw_semaphore`. For capabilities with an initialization function (e.g., `spin_lock_init()`), calling this function on the capability instance before initializing any diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index f1aaf676a874..d2bce28be68b 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -45,7 +45,7 @@ * reduce the chance that they will share the same cacheline causing * cacheline bouncing problem. */ -struct rw_semaphore { +struct_with_capability(rw_semaphore) { atomic_long_t count; /* * Write owner or one of the read owners as well flags regarding @@ -76,11 +76,13 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) } static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem) + __assumes_cap(sem) { WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE); } static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem) + __assumes_cap(sem) { WARN_ON(!(atomic_long_read(&sem->count) & RWSEM_WRITER_LOCKED)); } @@ -119,6 +121,7 @@ do { \ static struct lock_class_key __key; \ \ __init_rwsem((sem), #sem, &__key); \ + __assume_cap(sem); \ } while (0) /* @@ -148,7 +151,7 @@ extern bool is_rwsem_reader_owned(struct rw_semaphore *sem); #include -struct rw_semaphore { +struct_with_capability(rw_semaphore) { struct rwbase_rt rwbase; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; @@ -172,6 +175,7 @@ do { \ static struct lock_class_key __key; \ \ __init_rwsem((sem), #sem, &__key); \ + __assume_cap(sem); \ } while (0) static __always_inline int rwsem_is_locked(const struct rw_semaphore *sem) @@ -180,11 +184,13 @@ static __always_inline int rwsem_is_locked(const struct rw_semaphore *sem) } static __always_inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem) + __assumes_cap(sem) { WARN_ON(!rwsem_is_locked(sem)); } static __always_inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem) + __assumes_cap(sem) { WARN_ON(!rw_base_is_write_locked(&sem->rwbase)); } @@ -202,6 +208,7 @@ static __always_inline int rwsem_is_contended(struct rw_semaphore *sem) */ static inline void rwsem_assert_held(const struct rw_semaphore *sem) + __assumes_cap(sem) { if (IS_ENABLED(CONFIG_LOCKDEP)) lockdep_assert_held(sem); @@ -210,6 +217,7 @@ static inline void rwsem_assert_held(const struct rw_semaphore *sem) } static inline void rwsem_assert_held_write(const struct rw_semaphore *sem) + __assumes_cap(sem) { if (IS_ENABLED(CONFIG_LOCKDEP)) lockdep_assert_held_write(sem); @@ -220,48 +228,56 @@ static inline void rwsem_assert_held_write(const struct rw_semaphore *sem) /* * lock for reading */ -extern void down_read(struct rw_semaphore *sem); -extern int __must_check down_read_interruptible(struct rw_semaphore *sem); -extern int __must_check down_read_killable(struct rw_semaphore *sem); +extern void down_read(struct rw_semaphore *sem) __acquires_shared(sem); +extern int __must_check down_read_interruptible(struct rw_semaphore *sem) __cond_acquires_shared(0, sem); +extern int __must_check down_read_killable(struct rw_semaphore *sem) __cond_acquires_shared(0, sem); /* * trylock for reading -- returns 1 if successful, 0 if contention */ -extern int down_read_trylock(struct rw_semaphore *sem); +extern int down_read_trylock(struct rw_semaphore *sem) __cond_acquires_shared(true, sem); /* * lock for writing */ -extern void down_write(struct rw_semaphore *sem); -extern int __must_check down_write_killable(struct rw_semaphore *sem); +extern void down_write(struct rw_semaphore *sem) __acquires(sem); +extern int __must_check down_write_killable(struct rw_semaphore *sem) __cond_acquires(0, sem); /* * trylock for writing -- returns 1 if successful, 0 if contention */ -extern int down_write_trylock(struct rw_semaphore *sem); +extern int down_write_trylock(struct rw_semaphore *sem) __cond_acquires(true, sem); /* * release a read lock */ -extern void up_read(struct rw_semaphore *sem); +extern void up_read(struct rw_semaphore *sem) __releases_shared(sem); /* * release a write lock */ -extern void up_write(struct rw_semaphore *sem); +extern void up_write(struct rw_semaphore *sem) __releases(sem); -DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T)) -DEFINE_GUARD_COND(rwsem_read, _try, down_read_trylock(_T)) -DEFINE_GUARD_COND(rwsem_read, _intr, down_read_interruptible(_T), _RET == 0) +DEFINE_LOCK_GUARD_1(rwsem_read, struct rw_semaphore, down_read(_T->lock), up_read(_T->lock)) +DEFINE_LOCK_GUARD_1_COND(rwsem_read, _try, down_read_trylock(_T->lock)) +DEFINE_LOCK_GUARD_1_COND(rwsem_read, _intr, down_read_interruptible(_T->lock), _RET == 0) -DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T)) -DEFINE_GUARD_COND(rwsem_write, _try, down_write_trylock(_T)) -DEFINE_GUARD_COND(rwsem_write, _kill, down_write_killable(_T), _RET == 0) +DECLARE_LOCK_GUARD_1_ATTRS(rwsem_read, __assumes_cap(_T), /* */) +DECLARE_LOCK_GUARD_1_ATTRS(rwsem_read_try, __assumes_cap(_T), /* */) +DECLARE_LOCK_GUARD_1_ATTRS(rwsem_read_intr, __assumes_cap(_T), /* */) + +DEFINE_LOCK_GUARD_1(rwsem_write, struct rw_semaphore, down_write(_T->lock), up_write(_T->lock)) +DEFINE_LOCK_GUARD_1_COND(rwsem_write, _try, down_write_trylock(_T->lock)) +DEFINE_LOCK_GUARD_1_COND(rwsem_write, _kill, down_write_killable(_T->lock), _RET == 0) + +DECLARE_LOCK_GUARD_1_ATTRS(rwsem_write, __assumes_cap(_T), /* */) +DECLARE_LOCK_GUARD_1_ATTRS(rwsem_write_try, __assumes_cap(_T), /* */) +DECLARE_LOCK_GUARD_1_ATTRS(rwsem_write_kill, __assumes_cap(_T), /* */) /* * downgrade write lock to read lock */ -extern void downgrade_write(struct rw_semaphore *sem); +extern void downgrade_write(struct rw_semaphore *sem) __releases(sem) __acquires_shared(sem); #ifdef CONFIG_DEBUG_LOCK_ALLOC /* @@ -277,11 +293,11 @@ extern void downgrade_write(struct rw_semaphore *sem); * lockdep_set_class() at lock initialization time. * See Documentation/locking/lockdep-design.rst for more details.) */ -extern void down_read_nested(struct rw_semaphore *sem, int subclass); -extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass); -extern void down_write_nested(struct rw_semaphore *sem, int subclass); -extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass); -extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock); +extern void down_read_nested(struct rw_semaphore *sem, int subclass) __acquires_shared(sem); +extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass) __cond_acquires_shared(0, sem); +extern void down_write_nested(struct rw_semaphore *sem, int subclass) __acquires(sem); +extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass) __cond_acquires(0, sem); +extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock) __acquires(sem); # define down_write_nest_lock(sem, nest_lock) \ do { \ @@ -295,8 +311,8 @@ do { \ * [ This API should be avoided as much as possible - the * proper abstraction for this case is completions. ] */ -extern void down_read_non_owner(struct rw_semaphore *sem); -extern void up_read_non_owner(struct rw_semaphore *sem); +extern void down_read_non_owner(struct rw_semaphore *sem) __acquires_shared(sem); +extern void up_read_non_owner(struct rw_semaphore *sem) __releases_shared(sem); #else # define down_read_nested(sem, subclass) down_read(sem) # define down_read_killable_nested(sem, subclass) down_read_killable(sem) diff --git a/lib/test_capability-analysis.c b/lib/test_capability-analysis.c index 5b17fd94f31e..3c6dad0ba065 100644 --- a/lib/test_capability-analysis.c +++ b/lib/test_capability-analysis.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -255,6 +256,69 @@ static void __used test_seqlock_writer(struct test_seqlock_data *d) write_sequnlock_irqrestore(&d->sl, flags); } +struct test_rwsem_data { + struct rw_semaphore sem; + int counter __guarded_by(&sem); +}; + +static void __used test_rwsem_init(struct test_rwsem_data *d) +{ + init_rwsem(&d->sem); + d->counter = 0; +} + +static void __used test_rwsem_reader(struct test_rwsem_data *d) +{ + down_read(&d->sem); + (void)d->counter; + up_read(&d->sem); + + if (down_read_trylock(&d->sem)) { + (void)d->counter; + up_read(&d->sem); + } +} + +static void __used test_rwsem_writer(struct test_rwsem_data *d) +{ + down_write(&d->sem); + d->counter++; + up_write(&d->sem); + + down_write(&d->sem); + d->counter++; + downgrade_write(&d->sem); + (void)d->counter; + up_read(&d->sem); + + if (down_write_trylock(&d->sem)) { + d->counter++; + up_write(&d->sem); + } +} + +static void __used test_rwsem_assert(struct test_rwsem_data *d) +{ + rwsem_assert_held_nolockdep(&d->sem); + d->counter++; +} + +static void __used test_rwsem_guard(struct test_rwsem_data *d) +{ + { guard(rwsem_read)(&d->sem); (void)d->counter; } + { guard(rwsem_write)(&d->sem); d->counter++; } +} + +static void __used test_rwsem_cond_guard(struct test_rwsem_data *d) +{ + scoped_cond_guard(rwsem_read_try, return, &d->sem) { + (void)d->counter; + } + scoped_cond_guard(rwsem_write_try, return, &d->sem) { + d->counter++; + } +} + struct test_bit_spinlock_data { unsigned long bits; int counter __guarded_by(__bitlock(3, &bits)); -- 2.51.0.384.g4c02a37b29-goog