linux-kernel - Re: [PATCH] test_firmware: remove unnecessary test_fw_mutex in test_dev_config_show

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Message-ID: <20200416060011.GK11244@42.do-not-panic.com>
Date:   Thu, 16 Apr 2020 06:00:11 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Scott Branden <scott.branden@...adcom.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Brown <david.brown@...aro.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Shuah Khan <shuah@...nel.org>, bjorn.andersson@...aro.org,
        Shuah Khan <skhan@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        Olof Johansson <olof@...om.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Colin Ian King <colin.king@...onical.com>,
        Takashi Iwai <tiwai@...e.de>, linux-kselftest@...r.kernel.org,
        Andy Gross <agross@...nel.org>
Subject: Re: [PATCH] test_firmware: remove unnecessary test_fw_mutex in
 test_dev_config_show_xxx

On Wed, Apr 15, 2020 at 09:44:31AM -0700, Kees Cook wrote:
> On Wed, Apr 15, 2020 at 09:28:18AM -0700, Scott Branden wrote:
> > Hi Kees,
> > 
> > On 2020-04-14 8:10 p.m., Kees Cook wrote:
> > > On Tue, Apr 14, 2020 at 05:25:17PM -0700, Scott Branden wrote:
> > > > Remove unnecessary use of test_fw_mutex in test_dev_config_show_xxx
> > > > functions that show simple bool, int, and u8.
> > > I would expect at least a READ_ONCE(), yes?
> > I don't understand why you need a READ_ONCE when removing a mutex around an
> > assignment
> > of a parameter passed into a function being assigned to a local variable.
> > 
> > Could you please explain your expectations.
> 
> Oops, yes, you're right. I misread and was thinking this was reading
> from a global. This looks fine.
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>

Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>

  Luis