lkml.org 
[lkml]   [2011]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] comm: Introduce comm_lock spinlock to protect task->comm access
On Tue, 17 May 2011, Peter Zijlstra wrote:

> The changelog also fails to mention _WHY_ this is no longer true. Nor
> does it treat why making it true again isn't an option.
>

It's been true since:

4614a696bd1c3a9af3a08f0e5874830a85b889d4
Author: john stultz <johnstul@us.ibm.com>
Date: Mon Dec 14 18:00:05 2009 -0800

procfs: allow threads to rename siblings via /proc/pid/tasks/tid/comm

Although at the time it appears that nobody was concerned about races so
proper syncronization was never implemented. We always had the
prctl(PR_SET_NAME) so the majority of comm reads, those to current,
required no locking, but this commit changed that. The remainder of comm
dereferences always required task_lock() and the helper get_task_comm() to
read the string into a (usually stack-allocated) buffer.

> Who is changing another task's comm? That's just silly.
>

I agree, and I suggested taking write privileges away from /proc/pid/comm,
but others find that it is useful to be able to differentiate between
threads in the same thread group without using the prctl() for debugging?


\
 
 \ /
  Last update: 2011-05-18 00:59    [from the cache]
©2003-2011 Jasper Spaans