From: Peter Hurley <peter@hurleysoftware.com>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Kumar Gala <galak@codeaurora.org>,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
linux-arm-kernel@lists.infradead.org,
Rob Herring <robh@kernel.org>
Subject: Re: [PATCH] tty: serial: msm: Fix lock init issue with earlycon
Date: Tue, 21 Oct 2014 15:42:00 -0400 [thread overview]
Message-ID: <5446B708.6070404@hurleysoftware.com> (raw)
In-Reply-To: <20141020222003.GD12469@codeaurora.org>
On 10/20/2014 06:20 PM, Stephen Boyd wrote:
> On 10/20, Stephen Boyd wrote:
>> On 10/20, Peter Hurley wrote:
>>>
>>> FWIW, __msm_console_write() is a deadlock-waiting-to_happen since it does
>>> not disable interrupts with spin_lock_irqsave().
>>>
>>
>> Yeah we should fix that. As far as I can tell we've never used
>> the irqsave variant of the lock in the console path. Did this
>> become necessary at some point since this driver was introduced?
>> I'm wondering how many stable trees need the fix.
>
> Actually I don't see this case. It looks like the console is
> always called in call_console_drivers() with irqs saved and
> disabled via the logbuf_lock in console_cont_flush() or
> console_unlock().
Thanks for bringing that to my attention.
That looks like a vestige of the initial transition away from BKL.
I might look into just disabling preemption; even that might not
really be necessary.
Regards,
Peter Hurley
WARNING: multiple messages have this Message-ID (diff)
From: peter@hurleysoftware.com (Peter Hurley)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] tty: serial: msm: Fix lock init issue with earlycon
Date: Tue, 21 Oct 2014 15:42:00 -0400 [thread overview]
Message-ID: <5446B708.6070404@hurleysoftware.com> (raw)
In-Reply-To: <20141020222003.GD12469@codeaurora.org>
On 10/20/2014 06:20 PM, Stephen Boyd wrote:
> On 10/20, Stephen Boyd wrote:
>> On 10/20, Peter Hurley wrote:
>>>
>>> FWIW, __msm_console_write() is a deadlock-waiting-to_happen since it does
>>> not disable interrupts with spin_lock_irqsave().
>>>
>>
>> Yeah we should fix that. As far as I can tell we've never used
>> the irqsave variant of the lock in the console path. Did this
>> become necessary at some point since this driver was introduced?
>> I'm wondering how many stable trees need the fix.
>
> Actually I don't see this case. It looks like the console is
> always called in call_console_drivers() with irqs saved and
> disabled via the logbuf_lock in console_cont_flush() or
> console_unlock().
Thanks for bringing that to my attention.
That looks like a vestige of the initial transition away from BKL.
I might look into just disabling preemption; even that might not
really be necessary.
Regards,
Peter Hurley
next prev parent reply other threads:[~2014-10-21 19:42 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-17 13:13 [PATCH] tty: serial: msm: Fix lock init issue with earlycon Kumar Gala
2014-10-17 13:13 ` Kumar Gala
2014-10-20 18:27 ` Stephen Boyd
2014-10-20 18:27 ` Stephen Boyd
2014-10-20 21:38 ` Peter Hurley
2014-10-20 21:38 ` Peter Hurley
2014-10-20 22:16 ` Stephen Boyd
2014-10-20 22:16 ` Stephen Boyd
2014-10-20 22:20 ` Stephen Boyd
2014-10-20 22:20 ` Stephen Boyd
2014-10-21 19:42 ` Peter Hurley [this message]
2014-10-21 19:42 ` Peter Hurley
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5446B708.6070404@hurleysoftware.com \
--to=peter@hurleysoftware.com \
--cc=galak@codeaurora.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robh@kernel.org \
--cc=sboyd@codeaurora.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.