lkml.org 
[lkml]   [2016]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] locking/mutex: Set and clear owner using WRITE_ONCE()
On Mon, 23 May 2016, Jason Low wrote:

>On Fri, 2016-05-20 at 18:00 -0700, Davidlohr Bueso wrote:
>> On Fri, 20 May 2016, Waiman Long wrote:
>>
>> >I think mutex-debug.h also needs similar changes for completeness.
>>
>> Maybe, but given that with debug the wait_lock is unavoidable, doesn't
>> this send the wrong message?
>
>The mutex_set_owner() and mutex_clear_owner() can still get called in
>the fastpath without the wait_lock for the debug case too correct?

The fastpath is a nop, see mutex-null:

#define __mutex_fastpath_lock(count, fail_fn) fail_fn(count)

In anycase, if there were a fastpath, that would at least have an
ACQUIRE barrier (unless you set ->owner it before it or something
weird). But this isn't the case, so debug should be safe afaict.

Thanks,
Davidlohr

\
 
 \ /
  Last update: 2016-05-24 00:01    [W:0.066 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site