提交 fa59b0b0 编写于 作者: W Waiman Long 提交者: openeuler-sync-bot

locking/rwsem: Pass the current atomic count to rwsem_down_read_slowpath()

mainline inclusion
from mainline-v5.11-rc1
commit c8fe8b05
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7A0N9
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c8fe8b0564388f41147326f31e4587171aacccd4

--------------------------------

The atomic count value right after reader count increment can be useful
to determine the rwsem state at trylock time. So the count value is
passed down to rwsem_down_read_slowpath() to be used when appropriate.
Signed-off-by: NWaiman Long <longman@redhat.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NDavidlohr Bueso <dbueso@suse.de>
Link: https://lkml.kernel.org/r/20201121041416.12285-2-longman@redhat.com
Conflicts:
  kernel/locking/rwsem.c
[yyl: No functional changed.]
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
(cherry picked from commit 6f54c87c)
上级 70e33bec
......@@ -270,14 +270,14 @@ static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem)
owner | RWSEM_NONSPINNABLE));
}
static inline bool rwsem_read_trylock(struct rw_semaphore *sem)
static inline bool rwsem_read_trylock(struct rw_semaphore *sem, long *cntp)
{
long cnt = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count);
*cntp = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count);
if (WARN_ON_ONCE(cnt < 0))
if (WARN_ON_ONCE(*cntp < 0))
rwsem_set_nonspinnable(sem);
if (!(cnt & RWSEM_READ_FAILED_MASK)) {
if (!(*cntp & RWSEM_READ_FAILED_MASK)) {
rwsem_set_reader_owned(sem);
return true;
}
......@@ -996,9 +996,9 @@ rwsem_spin_on_owner(struct rw_semaphore *sem, unsigned long nonspinnable)
* Wait for the read lock to be granted
*/
static struct rw_semaphore __sched *
rwsem_down_read_slowpath(struct rw_semaphore *sem, int state)
rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, int state)
{
long count, adjustment = -RWSEM_READER_BIAS;
long adjustment = -RWSEM_READER_BIAS;
struct rwsem_waiter waiter;
DEFINE_WAKE_Q(wake_q);
bool wake = false;
......@@ -1344,16 +1344,20 @@ static struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
*/
static inline void __down_read(struct rw_semaphore *sem)
{
if (!rwsem_read_trylock(sem)) {
rwsem_down_read_slowpath(sem, TASK_UNINTERRUPTIBLE);
long count;
if (!rwsem_read_trylock(sem, &count)) {
rwsem_down_read_slowpath(sem, count, TASK_UNINTERRUPTIBLE);
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
}
}
static inline int __down_read_interruptible(struct rw_semaphore *sem)
{
if (!rwsem_read_trylock(sem)) {
if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_INTERRUPTIBLE)))
long count;
if (!rwsem_read_trylock(sem, &count)) {
if (IS_ERR(rwsem_down_read_slowpath(sem, count, TASK_INTERRUPTIBLE)))
return -EINTR;
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
}
......@@ -1362,8 +1366,10 @@ static inline int __down_read_interruptible(struct rw_semaphore *sem)
static inline int __down_read_killable(struct rw_semaphore *sem)
{
if (!rwsem_read_trylock(sem)) {
if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_KILLABLE)))
long count;
if (!rwsem_read_trylock(sem, &count)) {
if (IS_ERR(rwsem_down_read_slowpath(sem, count, TASK_KILLABLE)))
return -EINTR;
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
}
......
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