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Message-ID: <alpine.LFD.2.01.0907290859230.3161@localhost.localdomain>
Date: Wed, 29 Jul 2009 09:05:46 -0700 (PDT)
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
cc: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
"Rafael J. Wysocki" <rjw@...k.pl>, Ray Lee <ray-lk@...rabbit.org>,
LKML <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] kdesu broken
On Wed, 29 Jul 2009, Alan Cox wrote:
> > The tty_ldisc_hangup() already does tty_ldisc_wait_idle() after disabling
> > the timer (and clearing the TTY_LDISC bit), so that all seems fine
> > already. No?
>
> We only do tty_ldisc_wait_idle if tty->driver->flags & TTY_RESET_TERMIOS
> is set that I can see ?
I agree, but that's also the only time we do that 'tty_ldisc_halt()' that
cancels the timer. So if there is something that depends on the
flush_to_ldisc() not happening, the bug was pre-existing since it never
got rid of the flush to begin with, so the flush_to_ldisc() would happen
at some random later time as a result of the delayed-work timer.
That said, I suspect that from a sanity standpoint, I suspect something
like the appended migth be a good idea. But I think it's an independent
issue (and unless somebody can actually point to an actual problem, I'd
only apply something like this during the merge window, not after -rc4).
Linus
---
drivers/char/tty_ldisc.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index acd76b7..640b100 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -778,6 +778,8 @@ void tty_ldisc_hangup(struct tty_struct *tty)
if (ld->ops->hangup)
ld->ops->hangup(tty);
tty_ldisc_deref(ld);
+ tty_ldisc_halt(tty);
+ tty_ldisc_wait_idle(tty);
}
/*
* FIXME: Once we trust the LDISC code better we can wait here for
@@ -794,8 +796,6 @@ void tty_ldisc_hangup(struct tty_struct *tty)
mutex_lock(&tty->ldisc_mutex);
if (tty->ldisc) { /* Not yet closed */
/* Switch back to N_TTY */
- tty_ldisc_halt(tty);
- tty_ldisc_wait_idle(tty);
tty_ldisc_reinit(tty);
/* At this point we have a closed ldisc and we want to
reopen it. We could defer this to the next open but
--
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