From: Stanislav Kozina <skozina@redhat.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-serial@vger.kernel.org
Subject: Re: Patch for panic in n_tty_read()
Date: Wed, 08 Aug 2012 09:58:40 +0200 [thread overview]
Message-ID: <50221C30.20607@redhat.com> (raw)
In-Reply-To: <20120720161123.58fc9703@pyramind.ukuu.org.uk>
[-- Attachment #1: Type: text/plain, Size: 641 bytes --]
Alan,
I am not sure if you got my last email, so I'm resending it now:
> I am very sorry, but I don't see it. We didn't held the lock while
calling tty_audit_push() before, and we don't hold it after the patch
neither.
> So what's the locking scheme change here? Is there some binding
between n_tty_read() and tty_audit_push() I just don't see?
Please can you advice me why I should check this patch with audit folks?
Thanks a lot,
-Stanislav
>> Looks good to me. However it changes the locking rules on
>> tty_audit_push() so please check the audit folks are ok with it. I don't
>> think that causes any problems.
>>
>> Alan
[-- Attachment #2: tty_panic_2.patch --]
[-- Type: text/plain, Size: 774 bytes --]
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ee1c268..54d1fc5 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1832,13 +1832,13 @@ do_it_again:
if (tty->icanon && !L_EXTPROC(tty)) {
/* N.B. avoid overrun if nr == 0 */
+ spin_lock_irqsave(&tty->read_lock, flags);
while (nr && tty->read_cnt) {
int eol;
eol = test_and_clear_bit(tty->read_tail,
tty->read_flags);
c = tty->read_buf[tty->read_tail];
- spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = ((tty->read_tail+1) &
(N_TTY_BUF_SIZE-1));
tty->read_cnt--;
@@ -1864,6 +1864,7 @@ do_it_again:
tty_audit_push(tty);
break;
}
+ spin_lock_irqsave(&tty->read_lock, flags);
}
if (retval)
break;
next prev parent reply other threads:[~2012-08-08 7:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-25 15:41 Patch for panic in n_tty_read() Stanislav Kozina
2012-06-26 14:21 ` Alan Cox
2012-07-20 12:18 ` Stanislav Kozina
2012-07-20 15:11 ` Alan Cox
2012-07-27 12:05 ` Stanislav Kozina
2012-07-27 12:50 ` Alan Cox
2012-07-30 11:58 ` Stanislav Kozina
2012-08-08 7:58 ` Stanislav Kozina [this message]
2012-08-08 9:00 ` Alan Cox
2012-08-08 12:09 ` Stanislav Kozina
2012-08-08 12:26 ` Alan Cox
2012-08-08 14:32 ` Stanislav Kozina
2012-08-08 14:28 ` [PATCH V2] [tty] Fix possible race " Stanislav Kozina
2012-08-08 15:27 ` Alan Cox
2012-08-09 11:16 ` Stanislaw Gruszka
2012-08-13 15:26 ` Stanislaw Gruszka
2012-08-14 11:15 ` Stanislav Kozina
2012-08-09 11:24 ` Stanislav Kozina
2012-08-09 12:35 ` Alan Cox
2012-08-10 10:52 ` Stanislav Kozina
2012-08-10 10:51 ` [PATCH] Remove BUG_ON from n_tty_read() Stanislav Kozina
2012-08-10 12:29 ` Stanislaw Gruszka
2012-08-10 14:53 ` Stanislav Kozina
2012-08-10 14:38 ` [PATCH V2] " Stanislav Kozina
2012-08-16 7:52 ` Stanislav Kozina
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