linux-kernel - Re: [PATCH 1/2] tty: serial: msm_serial: Fix lockup for sysrq and oops

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Message-ID: <20191125012119.GA15822@leoy-ThinkPad-X240s>
Date:   Mon, 25 Nov 2019 09:21:19 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Jeffrey Hugo <jeffrey.l.hugo@...il.com>
Cc:     Andy Gross <agross@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Nicolas Dechesne <nicolas.dechesne@...aro.org>,
        MSM <linux-arm-msm@...r.kernel.org>,
        linux-serial@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] tty: serial: msm_serial: Fix lockup for sysrq and
 oops

Hi Jeffrey,

On Sun, Nov 24, 2019 at 04:00:21PM -0700, Jeffrey Hugo wrote:
> On Sun, Nov 24, 2019 at 8:44 AM Leo Yan <leo.yan@...aro.org> wrote:
> >
> > As the commit 677fe555cbfb ("serial: imx: Fix recursive locking bug")
> > has mentioned the uart driver might cause recursive locking between
> > normal printing and the kernel debugging facilities (e.g. sysrq and
> > oops).  In the commit it gave out suggestion for fixing recursive
> > locking issue: "The solution is to avoid locking in the sysrq case
> > and trylock in the oops_in_progress case."
> >
> > This patch follows the suggestion (also used the exactly same code with
> > other serial drivers, e.g. amba-pl011.c) to fix the recursive locking
> > issue, this can avoid stuck caused by deadlock and print out log for
> > sysrq and oops.
> >
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> 
> Shouldn't this patch have a Fixes tag?

Will add fixes tag in next spin.

> Was there a cover letter?

Okay, I will add cover letter for patch set v2.

Thanks for reviewing!
Leo