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| author | Thomas Gleixner <tglx@linutronix.de> | 2021-02-01 15:12:13 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-03 23:16:16 +0100 |
| commit | aa2f795a5bc171282a79c55d0a4e55cfdcea2845 (patch) | |
| tree | ce437efd6cc90906fa30e99710478a9537c06409 | |
| parent | 26f05b30e97d3bc30a20b52719d726f062539807 (diff) | |
| download | linux-stable-aa2f795a5bc171282a79c55d0a4e55cfdcea2845.tar.gz linux-stable-aa2f795a5bc171282a79c55d0a4e55cfdcea2845.tar.bz2 linux-stable-aa2f795a5bc171282a79c55d0a4e55cfdcea2845.zip | |
futex: Provide distinct return value when owner is exiting
commit ac31c7ff8624409ba3c4901df9237a616c187a5d upstream.
attach_to_pi_owner() returns -EAGAIN for various cases:
- Owner task is exiting
- Futex value has changed
The caller drops the held locks (hash bucket, mmap_sem) and retries the
operation. In case of the owner task exiting this can result in a live
lock.
As a preparatory step for seperating those cases, provide a distinct return
value (EBUSY) for the owner exiting case.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.935606117@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/futex.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index d21b151216aa..32d799b9bd20 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1909,12 +1909,13 @@ retry_private: if (!ret) goto retry; goto out; + case -EBUSY: case -EAGAIN: /* * Two reasons for this: - * - Owner is exiting and we just wait for the + * - EBUSY: Owner is exiting and we just wait for the * exit to complete. - * - The user space value changed. + * - EAGAIN: The user space value changed. */ free_pi_state(pi_state); pi_state = NULL; @@ -2580,12 +2581,13 @@ retry_private: goto out_unlock_put_key; case -EFAULT: goto uaddr_faulted; + case -EBUSY: case -EAGAIN: /* * Two reasons for this: - * - Task is exiting and we just wait for the + * - EBUSY: Task is exiting and we just wait for the * exit to complete. - * - The user space value changed. + * - EAGAIN: The user space value changed. */ queue_unlock(hb); put_futex_key(&q.key); |