lkml.org 
[lkml]   [2005]   [Dec]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] - Fix memory ordering problem in wake_futex()
Again replying to myself, sorry:

Jack Steiner wrote:

>On Fri, Dec 23, 2005 at 11:23:11PM +0100, Manfred Spraul wrote:
>
>
>>Bad race.
>>Unfortuantely the scenario that you describe is quite frequent:
>>- autoremove_wake_function()
>>
>>
Not a bug, but for very subtile reasons:
There are no writes to the wait_queue structure except the
list_del_init(), and for list_del_init() no memory barriers are required
because finish_wait() uses list_empty_careful(), i.e. the spin_lock() is
only bypassed if both write operations from list_del_init() have completed.

>>- ipc/sem.c (search for IN_WAKEUP)
>>
>>
fixed in -rc7.


--
Manfred
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-12-25 17:05    [W:0.049 / U:0.440 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site