On Wed, Sep 06, 2006 at 03:07:53AM +0400, Oleg Nesterov wrote:
> Nowadays ->signal/->sighand are _also_ protected by ->sighand->siglock.
> Unless you are current, you can't lock ->siglock directly (without holding
> tasklist_lock), you should use lock_task_sighand().
Gack, that makes current controlling tty locking horrible (and wrong almost
everywhere still across a clone)
> tty_io.c:
> ->tty is set under task_lock()
>
> ->tty is cleared under lock_kernel() + tasklist_lock
>
> except TIOCNOTTY, cleared under task_lock()
>
> Note that include/linux/sched.h doesn't document that ->alloc_lock
> protects ->tty, it is only used in tty_io.c for that purpose, why?
Work in progress
> Btw, I think tiocsctty()/tty_open() is racy wrt to sys_setsid().
> tiocsctty() can see the result of '->signal->leader = 1' before
> sys_setsid() changed ->session/->pgrp and passed '->tty = NULL'.
Correct. I'm doing them bit by bit as I unpick them and check they
don't deadlock. If we need to take task_lock as well then its time
for set_controlling_tty() to get added.
Thanks for the signal lock explanation though. Now I've more idea wtf
is going on below the tty layer
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
