diff options
| -rw-r--r-- | include/linux/sched.h | 29 | ||||
| -rw-r--r-- | kernel/futex/futex.h | 6 | ||||
| -rw-r--r-- | kernel/locking/ww_mutex.h | 6 |
3 files changed, 25 insertions, 16 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 2b272382673d..f8188b833350 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2152,6 +2152,8 @@ static inline struct mutex *__get_task_blocked_on(struct task_struct *p) static inline void __set_task_blocked_on(struct task_struct *p, struct mutex *m) { + struct mutex *blocked_on = READ_ONCE(p->blocked_on); + WARN_ON_ONCE(!m); /* The task should only be setting itself as blocked */ WARN_ON_ONCE(p != current); @@ -2162,8 +2164,8 @@ static inline void __set_task_blocked_on(struct task_struct *p, struct mutex *m) * with a different mutex. Note, setting it to the same * lock repeatedly is ok. */ - WARN_ON_ONCE(p->blocked_on && p->blocked_on != m); - p->blocked_on = m; + WARN_ON_ONCE(blocked_on && blocked_on != m); + WRITE_ONCE(p->blocked_on, m); } static inline void set_task_blocked_on(struct task_struct *p, struct mutex *m) @@ -2174,16 +2176,19 @@ static inline void set_task_blocked_on(struct task_struct *p, struct mutex *m) static inline void __clear_task_blocked_on(struct task_struct *p, struct mutex *m) { - WARN_ON_ONCE(!m); - /* Currently we serialize blocked_on under the mutex::wait_lock */ - lockdep_assert_held_once(&m->wait_lock); - /* - * There may be cases where we re-clear already cleared - * blocked_on relationships, but make sure we are not - * clearing the relationship with a different lock. - */ - WARN_ON_ONCE(m && p->blocked_on && p->blocked_on != m); - p->blocked_on = NULL; + if (m) { + struct mutex *blocked_on = READ_ONCE(p->blocked_on); + + /* Currently we serialize blocked_on under the mutex::wait_lock */ + lockdep_assert_held_once(&m->wait_lock); + /* + * There may be cases where we re-clear already cleared + * blocked_on relationships, but make sure we are not + * clearing the relationship with a different lock. + */ + WARN_ON_ONCE(blocked_on && blocked_on != m); + } + WRITE_ONCE(p->blocked_on, NULL); } static inline void clear_task_blocked_on(struct task_struct *p, struct mutex *m) diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index c74eac572acd..2cd57096c38e 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -319,13 +319,13 @@ static __always_inline int futex_put_value(u32 val, u32 __user *to) { if (can_do_masked_user_access()) to = masked_user_access_begin(to); - else if (!user_read_access_begin(to, sizeof(*to))) + else if (!user_write_access_begin(to, sizeof(*to))) return -EFAULT; unsafe_put_user(val, to, Efault); - user_read_access_end(); + user_write_access_end(); return 0; Efault: - user_read_access_end(); + user_write_access_end(); return -EFAULT; } diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h index 086fd5487ca7..31a785afee6c 100644 --- a/kernel/locking/ww_mutex.h +++ b/kernel/locking/ww_mutex.h @@ -342,8 +342,12 @@ static bool __ww_mutex_wound(struct MUTEX *lock, * When waking up the task to wound, be sure to clear the * blocked_on pointer. Otherwise we can see circular * blocked_on relationships that can't resolve. + * + * NOTE: We pass NULL here instead of lock, because we + * are waking the mutex owner, who may be currently + * blocked on a different mutex. */ - __clear_task_blocked_on(owner, lock); + __clear_task_blocked_on(owner, NULL); wake_q_add(wake_q, owner); } return true; |