diff options
| -rw-r--r-- | kernel/futex.c | 38 |
1 files changed, 34 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index fac0c1747396..7eeb56d61f48 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -3684,7 +3684,7 @@ static void exit_robust_list(struct task_struct *curr) } } -void futex_exec_release(struct task_struct *tsk) +static void futex_cleanup(struct task_struct *tsk) { if (unlikely(tsk->robust_list)) { exit_robust_list(tsk); @@ -3724,7 +3724,7 @@ void futex_exit_recursive(struct task_struct *tsk) tsk->futex_state = FUTEX_STATE_DEAD; } -void futex_exit_release(struct task_struct *tsk) +static void futex_cleanup_begin(struct task_struct *tsk) { /* * Switch the state to FUTEX_STATE_EXITING under tsk->pi_lock. @@ -3740,10 +3740,40 @@ void futex_exit_release(struct task_struct *tsk) raw_spin_lock_irq(&tsk->pi_lock); tsk->futex_state = FUTEX_STATE_EXITING; raw_spin_unlock_irq(&tsk->pi_lock); +} - futex_exec_release(tsk); +static void futex_cleanup_end(struct task_struct *tsk, int state) +{ + /* + * Lockless store. The only side effect is that an observer might + * take another loop until it becomes visible. + */ + tsk->futex_state = state; +} - tsk->futex_state = FUTEX_STATE_DEAD; +void futex_exec_release(struct task_struct *tsk) +{ + /* + * The state handling is done for consistency, but in the case of + * exec() there is no way to prevent futher damage as the PID stays + * the same. But for the unlikely and arguably buggy case that a + * futex is held on exec(), this provides at least as much state + * consistency protection which is possible. + */ + futex_cleanup_begin(tsk); + futex_cleanup(tsk); + /* + * Reset the state to FUTEX_STATE_OK. The task is alive and about + * exec a new binary. + */ + futex_cleanup_end(tsk, FUTEX_STATE_OK); +} + +void futex_exit_release(struct task_struct *tsk) +{ + futex_cleanup_begin(tsk); + futex_cleanup(tsk); + futex_cleanup_end(tsk, FUTEX_STATE_DEAD); } long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |