xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

locking/rwsem: Check for operations on an uninitialized rwsem

Browse Source 
Currently rwsems is the only locking primitive that lacks this
debug feature. Add it under CONFIG_DEBUG_RWSEMS and do the magic
checking in the locking fastpath (trylock) operation such that
we cover all cases. The unlocking part is pretty straightforward.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: mingo@kernel.org
Cc: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lkml.kernel.org/r/20190729044735.9632-1-dave@stgolabs.net
This commit is contained in:
Davidlohr Bueso
2019-07-28 21:47:35 -07:00
committed by Peter Zijlstra
parent 91d2a812df
commit fce45cd411
2 changed files with 28 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
kernel/locking/rwsem.c
View File

@@ -105,8 +105,9 @@
#ifdef CONFIG_DEBUG_RWSEMS
# define DEBUG_RWSEMS_WARN_ON(c, sem) do { \
if (!debug_locks_silent && \
WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\
WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, magic = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\
#c, atomic_long_read(&(sem)->count), \
(unsigned long) sem->magic, \
atomic_long_read(&(sem)->owner), (long)current, \
list_empty(&(sem)->wait_list) ? "" : "not ")) \
debug_locks_off(); \
@@ -329,6 +330,9 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
*/
debug_check_no_locks_freed((void *)sem, sizeof(*sem));
lockdep_init_map(&sem->dep_map, name, key, 0);
#endif
#ifdef CONFIG_DEBUG_RWSEMS
sem->magic = sem;
#endif
atomic_long_set(&sem->count, RWSEM_UNLOCKED_VALUE);
raw_spin_lock_init(&sem->wait_lock);
@@ -1358,11 +1362,14 @@ static inline int __down_read_killable(struct rw_semaphore *sem)
static inline int __down_read_trylock(struct rw_semaphore *sem)
{
long tmp;
DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
/*
* Optimize for the case when the rwsem is not locked at all.
*/
long tmp = RWSEM_UNLOCKED_VALUE;
tmp = RWSEM_UNLOCKED_VALUE;
do {
if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp,
tmp + RWSEM_READER_BIAS)) {
@@ -1403,8 +1410,11 @@ static inline int __down_write_killable(struct rw_semaphore *sem)
static inline int __down_write_trylock(struct rw_semaphore *sem)
{
long tmp = RWSEM_UNLOCKED_VALUE;
long tmp;
DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
tmp = RWSEM_UNLOCKED_VALUE;
if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp,
RWSEM_WRITER_LOCKED)) {
rwsem_set_owner(sem);
@@ -1420,7 +1430,9 @@ inline void __up_read(struct rw_semaphore *sem)
{
long tmp;
DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
rwsem_clear_reader_owned(sem);
tmp = atomic_long_add_return_release(-RWSEM_READER_BIAS, &sem->count);
DEBUG_RWSEMS_WARN_ON(tmp < 0, sem);
@@ -1438,12 +1450,14 @@ static inline void __up_write(struct rw_semaphore *sem)
{
long tmp;
DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
/*
* sem->owner may differ from current if the ownership is transferred
* to an anonymous writer by setting the RWSEM_NONSPINNABLE bits.
*/
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) &&
!rwsem_test_oflags(sem, RWSEM_NONSPINNABLE), sem);
rwsem_clear_owner(sem);
tmp = atomic_long_fetch_add_release(-RWSEM_WRITER_LOCKED, &sem->count);
if (unlikely(tmp & RWSEM_FLAG_WAITERS))