linux-kernel - Re: [ldv-project] [PATCH] drivers: watchdog: rdc321x

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Message-ID: <6fb7fc90-1577-98ac-2be3-a8aa631f11ef@roeck-us.net>
Date:   Fri, 7 Aug 2020 12:00:56 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Evgeny Novikov <novikov@...ras.ru>,
        "madhuparnabhowmik10@...il.com" <madhuparnabhowmik10@...il.com>
Cc:     "ldv-project@...uxtesting.org" <ldv-project@...uxtesting.org>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>
Subject: Re: [ldv-project] [PATCH] drivers: watchdog: rdc321x_wdt: Fix race
 condition bugs

On 8/7/20 11:30 AM, Evgeny Novikov wrote:
> 07.08.2020, 19:21, "Guenter Roeck" <linux@...ck-us.net>:
>> On Fri, Aug 07, 2020 at 04:59:02PM +0530, madhuparnabhowmik10@...il.com wrote:
>>>  From: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
>>>
>>>  In rdc321x_wdt_probe(), rdc321x_wdt_device.queue is initialized
>>>  after misc_register(), hence if ioctl is called before its
>>>  initialization which can call rdc321x_wdt_start() function,
>>>  it will see an uninitialized value of rdc321x_wdt_device.queue,
>>>  hence initialize it before misc_register().
>>>  Also, rdc321x_wdt_device.default_ticks is accessed in reset()
>>>  function called from write callback, thus initialize it before
>>>  misc_register().
>>>
>>>  Found by Linux Driver Verification project (linuxtesting.org).
>>>
>>>  Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
>>
>> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
>>
>> Having said that ... this is yet another potentially obsolete driver.
>> You are really wasting your (and, fwiw, my) time.
> 
> Static analysis tools are not aware about obsolete drivers.
> It would be great if there will be some formal way to filter them out.
> Maybe some file will enumerate all obsolete drivers, or there will be
> something within their source code, or something else.
> 

In general, all watchdog drivers not implementing the watchdog API
are effectively obsolete and should not be touched. If they are still
in use (meaning someone has a means to test them), they should be
converted to use the watchdog API instead.

Guenter