linux-kernel - Re: [PATCH v2 5/7] Watchdog: introduce "pretimeout" into framework

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Date:	Mon, 25 May 2015 11:09:00 +0800
From:	Fu Wei <fu.wei@...aro.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
	linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	Wei Fu <tekkamanninja@...il.com>,
	G Gregory <graeme.gregory@...aro.org>,
	Al Stone <al.stone@...aro.org>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Timur Tabi <timur@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, vgandhi@...eaurora.org,
	wim@...ana.be, Jon Masters <jcm@...hat.com>,
	Leo Duran <leo.duran@....com>, Jon Corbet <corbet@....net>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 5/7] Watchdog: introduce "pretimeout" into framework

Hi Guenter,

Great thanks for your suggestion,

I have put this kind of validation into watchdog_pretimeout_invalid
and watchdog_timeout_invalid.

So :

(1)
 set_timeout(10);   ------> if this setting is successful
 set_pretimeout(20); ----->  return fail (-EINVAL)


(2)
set_timeout(10);  ------> if this setting is successful
set_pretimeout(10); ----->  return fail (-EINVAL)

this kind of situation will not result in an invalid / unexpected timeout value.

you will see this change in my next patchset

On 21 May 2015 at 23:32, Guenter Roeck <linux@...ck-us.net> wrote:
> On Thu, May 21, 2015 at 04:32:34PM +0800, fu.wei@...aro.org wrote:
>> From: Fu Wei <fu.wei@...aro.org>
>>
>> Also update Documentation/watchdog/watchdog-kernel-api.txt to
>> introduce:
>> (1)the new elements in the watchdog_device and watchdog_ops struct;
>> (2)the new API "watchdog_init_timeouts".
>>
>> Reasons:
>> (1)kernel already has two watchdog drivers are using "pretimeout":
>>       drivers/char/ipmi/ipmi_watchdog.c
>>       drivers/watchdog/kempld_wdt.c(but the definition is different)
>> (2)some other dirvers are going to use this: ARM SBSA Generic Watchdog
>>
>> Signed-off-by: Fu Wei <fu.wei@...aro.org>
>> ---
>
> [ ... ]
>
>>
>> +/* Use the following function to check if a pretimeout value is invalid */
>> +static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
>> +                                            unsigned int t)
>> +{
>> +     return ((wdd->max_pretimeout != 0) &&
>> +             (t < wdd->min_pretimeout || t > wdd->max_pretimeout));
>> +}
>
> Should this function also enforce "t < wdd->timeout", and
> should watchdog_timeout_invalid() enforce "t > wdd->pretimeout" ?
>
> Thanks,
> Guenter



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
Ph: +86 21 61221326(direct)
Ph: +86 186 2020 4684 (mobile)
Room 1512, Regus One Corporate Avenue,Level 15,
One Corporate Avenue,222 Hubin Road,Huangpu District,
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