diff options
Diffstat (limited to 'include/linux/futex.h')
| -rw-r--r-- | include/linux/futex.h | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h index d6ed11c51a8e..025ad96bcf9d 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -50,6 +50,10 @@ union futex_key { #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } } #ifdef CONFIG_FUTEX +enum { + FUTEX_STATE_OK, + FUTEX_STATE_DEAD, +}; static inline void futex_init_task(struct task_struct *tsk) { @@ -59,6 +63,34 @@ static inline void futex_init_task(struct task_struct *tsk) #endif INIT_LIST_HEAD(&tsk->pi_state_list); tsk->pi_state_cache = NULL; + tsk->futex_state = FUTEX_STATE_OK; +} + +/** + * futex_exit_done - Sets the tasks futex state to FUTEX_STATE_DEAD + * @tsk: task to set the state on + * + * Set the futex exit state of the task lockless. The futex waiter code + * observes that state when a task is exiting and loops until the task has + * actually finished the futex cleanup. The worst case for this is that the + * waiter runs through the wait loop until the state becomes visible. + * + * This has two callers: + * + * - futex_mm_release() after the futex exit cleanup has been done + * + * - do_exit() from the recursive fault handling path. + * + * In case of a recursive fault this is best effort. Either the futex exit + * code has run already or not. If the OWNER_DIED bit has been set on the + * futex then the waiter can take it over. If not, the problem is pushed + * back to user space. If the futex exit code did not run yet, then an + * already queued waiter might block forever, but there is nothing which + * can be done about that. + */ +static inline void futex_exit_done(struct task_struct *tsk) +{ + tsk->futex_state = FUTEX_STATE_DEAD; } void futex_mm_release(struct task_struct *tsk); @@ -68,6 +100,7 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, #else static inline void futex_init_task(struct task_struct *tsk) { } static inline void futex_mm_release(struct task_struct *tsk) { } +static inline void futex_exit_done(struct task_struct *tsk) { } static inline long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, u32 __user *uaddr2, u32 val2, u32 val3) |