Re: possible locking bug in tty_open

[Alan Cox]

On Sun, 2 May 2010 22:47:33 +0200
Arnd Bergmann <arnd@xxxxxxxx> wrote:

> While playing some more with my TTY BKL patches, I stumbled over
> what looks like a bug in tty_open, introduced in e8c6210 
> "tty: push the BKL down into the handlers a bit":
> 
> After the "retry_open:" label, we first get the tty_mutex
> and then the BKL. However a the end of tty_open, we jump
> back to retry_open with the BKL still held. If we run into
> this case, the tty_open function will be left with the BKL
> still held.
> 
> It may be impossible to actually trigger this bug, because
> the path is only taken if a tty driver open function returns
> -ERESTARTSYS without setting signal_pending().

It looks pretty much impossible to trigger but it's definitely a bug.
I'll send Greg a patch
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/