lkml.org 
[lkml]   [2008]   [May]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Fix SMP alternatives : use mutex instead of spinlock, text_poke is sleepable
* Linus Torvalds (torvalds@linux-foundation.org) wrote:
>
>
> On Thu, 1 May 2008, Mathieu Desnoyers wrote:
> >
> > Yep. I think using a mutex should fix it. There is no reason to use a
> > spinlock rather than a mutex here.
>
> Is there any reason to do any locking what-so-ever?
>
> If this code could possibly race with something else, that sounds like a
> bug in itself, no?
>
> Linus

The smp_alt mutex taken in
alternatives_smp_module_add/alternatives_smp_module_del seems required
because this code will run at module load/free, even in SMP context (not
within stop_machine_run).

As for alternatives_smp_switch, which is called when switching between
UP and SMP, always in UP context, I guess we should assume it could be
executed concurrently wrt the module_load/free, even in UP on a
CONFIG_PREEMPT kernel.

Mathieu


--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68


\
 
 \ /
  Last update: 2008-05-01 22:11    [W:0.193 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site