shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-08 03:40:35 +09:00
Code Issues Packages Projects Releases Wiki Activity

futex: Provide distinct return value when owner is exiting

Browse Source 
commit ac31c7ff86 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>
This commit is contained in:
Thomas Gleixner
2021-02-01 10:01:42 +00:00
committed by Greg Kroah-Hartman
parent ad3466ae9d
commit c27f392040
1 changed files with 6 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/futex.c
View File

@@ -1918,12 +1918,13 @@ 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.
*/
double_unlock_hb(hb1, hb2);
hb_waiters_dec(hb2);
@@ -2615,12 +2616,13 @@ 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);