linux-kernel - Re: [PATCH v2] drivers/tty/serial: check the return value of uart_port

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Message-ID: <2033d06d-10a4-5a57-d650-7541c39990ee@linux.intel.com>
Date:   Mon, 29 Aug 2022 10:09:25 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Li Zhong <floridsleeves@...il.com>
cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH v2] drivers/tty/serial: check the return value of
 uart_port_check()

On Sun, 28 Aug 2022, Li Zhong wrote:

> On Fri, Aug 26, 2022 at 9:01 AM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
> >
> > On Fri, Aug 26, 2022 at 11:38 AM Li Zhong <floridsleeves@...il.com> wrote:
> > >
> > > uart_port_check() will return NULL pointer when state->uart_port is
> > > NULL. Check the return value before dereference it to avoid
> > > null-pointer-dereference error.
> >
> > Have you taken the locking into consideration?
> > If no, please do, if yes, expand your commit message to explain why
> > the current locking scheme doesn't prevent an error from happening.
> >
> 
> The locking is taken into consideration but these three checks do not need to
> unlock in error-handling because unlock() will be called in the callers. Will
> add the comment in v2 patch.

I think he meant you should indicate why the current locking doesn't cover 
the case you're fixing, not whether this function should call unlock() or 
not.

-- 
 i.