lkml.org 
[lkml]   [2018]   [Jan]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 3/3] tty: Use RCU read lock to iterate tasks and threads in __do_SAK()
On 01/17, Eric W. Biederman wrote:
>
> __do_SAK() needs to be 100% accurate.

But it can't. A process/thread can open tty right after the check.

> I do not see the rcu_read_lock
> guaranteeing that new processes created while the process list is being
> iterated that happen to have a reference to the tty will be seen.

We can't miss the new child if its parent has this tty opened at fork() time,
__do_SAK() sends SIGKILL and ->siglock serializes __do_SAK() with copy_process()
which checks signal_pending() under the same ->siglock. So either fork() should
fail or for_each_process() should see the new child.

Right?

Otherwise we do not care. The child can open tty later but this doesn't differ
from the "race" above.

Oleg.

\
 
 \ /
  Last update: 2018-01-18 00:21    [W:0.140 / U:1.332 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site