lkml.org 
[lkml]   [2010]   [Mar]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH -mm 3/3] proc: make task_sig() lockless
On 03/23, David Howells wrote:
>
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > task_sig() doesn't need ->siglock.
>
> Except that the data returned might then be inconsistent because you don't
> hold a lock as you read the various bits of it.

Yes. From the changelog:

Of course, this means we read pending/blocked/etc nonatomically,
but I hope this is OK for fs/proc.

But I don't think the returned data could be "really" inconsistent
from the /bin/ps pov. Yes, it is possible that, say, some signal is
seen as both pending and ignored without ->siglock. Or we can report
user->sigpending != 0 while pending/shpending are empty.

But this looks harmless to me. We never guaranteed /proc/pid/status
can't report the "intermediate" state, and I don't think we can
confuse the user-space.

Do you agree? Or do you think this can make problems ?

Oleg.



\
 
 \ /
  Last update: 2010-03-23 12:01    [W:0.077 / U:0.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site