linux-kernel - Re: [PATCH resend] serial_core: Fix pm imbalance on unbind

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMuHMdUBiUzpvTzkhaguOQoDc8XJH7NvnNe2Z+jL6UeEitpJPg@mail.gmail.com>
Date:	Fri, 21 Mar 2014 14:23:49 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>, linux-serial@...r.kernel.org,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Geert Uytterhoeven <geert+renesas@...ux-m68k.org>
Subject: Re: [PATCH resend] serial_core: Fix pm imbalance on unbind

Hi Peter,

On Fri, Mar 21, 2014 at 2:06 PM, Peter Hurley <peter@...leysoftware.com> wrote:
>> @@ -2681,10 +2683,12 @@ int uart_remove_one_port(struct uart_driver *drv,
>> struct uart_port *uport)
>>         }
>>
>>         /*
>> -        * If the port is used as a console, unregister it
>> +        * If the port is used as a console, unregister it, and power it
>> down
>>          */
>> -       if (uart_console(uport))
>> +       if (uart_console(uport)) {
>>                 unregister_console(uport->cons);
>> +               uart_change_pm(state, UART_PM_STATE_OFF);
>
> Won't this power off the port while tty consoles may still be open?

I didn't see that actually happening.

> I think the right thing here is to unregister_console then set uport->cons =
> NULL
>
> [uport->cons is properly reassigned when/if a port is re-added via
> uart_add_one_port()).]

But indeed, for concistency/symmetry uport->state and uport->cons
should be resend, but that's something separate.

> Then, uart_close() will power off the port when all ttys using the port have
> been closed.

uart_close() won't get that far, so uart_change_pm() won't be called.

See also https://lkml.org/lkml/2014/3/10/651, and my workaround for the
crash https://lkml.org/lkml/2014/3/17/231.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/