linux-kernel - Re: [PATCH] watchdog: mena21_wdt: Fix a possible data race in a21_wdt_set

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Message-ID: <26fde8a3-fb78-e12f-2f0f-c9b5bb2158e0@gmail.com>
Date:   Tue, 8 May 2018 11:32:20 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>, morbidrsa@...il.com,
        wim@...ux-watchdog.org
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: mena21_wdt: Fix a possible data race in
 a21_wdt_set_timeout



On 2018/5/8 11:28, Guenter Roeck wrote:
> On 05/07/2018 08:18 PM, Jia-Ju Bai wrote:
>> The write operation to "wdt->timeout" is protected by
>> the lock on line 118, but the read operation to
>> this data on line 105 is not protected by the lock.
>> Thus, there may exist a data race for "wdt->timeout".
>>
>> To fix this data race, the read operation to "wdt->timeout"
>> should be also protected by the lock.
>>
>
> There is no race. There is already a mutex in the watchdog core which 
> serializes
> calls to the various API functions. It would make more sense to drop 
> drv->lock
> from the driver.
>

Thanks for your reply :)
Need I submit a patch of dropping all calls to "drv->lock"?


Best wishes,
Jia-Ju Bai