Re: [PATCH] - Fix memory ordering problem in wake_futex()

[Manfred Spraul]

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
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