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Date: Fri, 15 May 2015 21:49:07 +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>
Subject: Re: [PATCH 4/6] Watchdog: introdouce "pretimeout" into framework
Hi Guenter,
Great thanks for your review,
feedback inline below :-)
On 15 May 2015 at 21:33, Guenter Roeck <linux@...ck-us.net> wrote:
> On 05/15/2015 04:24 AM, fu.wei@...aro.org wrote:
>>
>> From: Fu Wei <fu.wei@...aro.org>
>>
>> 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>
>> ---
>> drivers/watchdog/watchdog_core.c | 66
>> ++++++++++++++++++++++++++++++++++++++++
>> drivers/watchdog/watchdog_dev.c | 48 +++++++++++++++++++++++++++++
>> include/linux/watchdog.h | 19 ++++++++++++
>> 3 files changed, 133 insertions(+)
>>
>> diff --git a/drivers/watchdog/watchdog_core.c
>> b/drivers/watchdog/watchdog_core.c
>> index cec9b55..6ca9578 100644
>> --- a/drivers/watchdog/watchdog_core.c
>> +++ b/drivers/watchdog/watchdog_core.c
>> @@ -54,6 +54,14 @@ static void watchdog_check_min_max_timeout(struct
>> watchdog_device *wdd)
>> wdd->min_timeout = 0;
>> wdd->max_timeout = 0;
>> }
>> + if (wdd->min_pretimeout && wdd->min_timeout < wdd->min_pretimeout)
>> {
>> + pr_info("Invalid min timeout, resetting to min
>> pretimeout!\n");
>> + wdd->min_timeout = wdd->min_pretimeout;
>> + }
>> + if (wdd->max_pretimeout && wdd->max_timeout < wdd->max_pretimeout)
>> {
>> + pr_info("Invalid max timeout, resetting to max
>> pretimeout!\n");
>> + wdd->max_timeout = wdd->max_pretimeout;
>> + }
>
>
> I am a bit concerned about the context dependency introduced here. If
> someone calls
> _init_pretimeout after calling init_timeout, this may result in still
> invalid timeout
> values.
yes, that logic is not very clean, so my thought is :
maybe we can integrate watchdog_init_timeout and watchdog_init_pretimeout,
if maintainer agree to add pretimeout into framework.
>
>
>> }
>>
>> /**
>> @@ -98,6 +106,63 @@ int watchdog_init_timeout(struct watchdog_device *wdd,
>> }
>> EXPORT_SYMBOL_GPL(watchdog_init_timeout);
>>
>> +static void watchdog_check_min_max_pretimeout(struct watchdog_device
>> *wdd)
>> +{
>> + /*
>> + * Check that we have valid min and max pretimeout values, if
>> + * not reset them both to 0 (=not used or unknown)
>> + */
>> + if (wdd->min_pretimeout > wdd->max_pretimeout) {
>> + pr_info("Invalid min and max pretimeout, resetting to
>> 0!\n");
>> + wdd->min_pretimeout = 0;
>> + wdd->max_pretimeout = 0;
>> + }
>> +}
>> +
>> +/**
>> + * watchdog_init_pretimeout() - initialize the pretimeout field
>> + * @pretimeout_parm: pretimeout module parameter
>> + * @dev: Device that stores the timeout-sec property
>> + *
>> + * Initialize the pretimeout field of the watchdog_device struct with
>> either
>> + * the pretimeout module parameter (if it is valid value) or the
>> timeout-sec
>> + * property (only if it is a valid value and the timeout_parm is out of
>> bounds).
>> + * If none of them are valid then we keep the old value (which should
>> normally
>> + * be the default pretimeout value.
>> + *
>> + * A zero is returned on success and -EINVAL for failure.
>> + */
>
>
> The new API function also needs to be documented in
> Documentation/watchdog/watchdog-kernel-api.txt.
good point, thanks will do
>
>> +int watchdog_init_pretimeout(struct watchdog_device *wdd,
>> + unsigned int pretimeout_parm, struct device
>> *dev)
>> +{
>> + int ret = 0;
>> + u32 timeouts[2];
>> +
>> + watchdog_check_min_max_pretimeout(wdd);
>> +
>> + /* try to get the timeout module parameter first */
>> + if (!watchdog_pretimeout_invalid(wdd, pretimeout_parm) &&
>> + pretimeout_parm) {
>> + wdd->pretimeout = pretimeout_parm;
>> + return ret;
>> + }
>> + if (pretimeout_parm)
>> + ret = -EINVAL;
>> +
>> + /* try to get the timeout_sec property */
>> + if (!dev || !dev->of_node)
>> + return ret;
>> + ret = of_property_read_u32_array(dev->of_node,
>> + "timeout-sec", timeouts, 2);
>> + if (!watchdog_pretimeout_invalid(wdd, timeouts[1]) && timeouts[1])
>
>
> Guess we are still waiting for feedback from the devicetree maintainers on
> this.
yes!
>
> Both the above synchronization concern and this makes me wonder if we should
> introduce
> watchdog_init_timeouts() instead, which would take pretimeout as additional
> parameter.
> What do you think about that ?
yes, that is what I am thinking about
>
>
>> + wdd->pretimeout = timeouts[1];
>> + else
>> + ret = -EINVAL;
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(watchdog_init_pretimeout);
>> +
>> /**
>> * watchdog_register_device() - register a watchdog device
>> * @wdd: watchdog device
>> @@ -119,6 +184,7 @@ int watchdog_register_device(struct watchdog_device
>> *wdd)
>> if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
>> return -EINVAL;
>>
>> + watchdog_check_min_max_pretimeout(wdd);
>> watchdog_check_min_max_timeout(wdd);
>>
>> /*
>> diff --git a/drivers/watchdog/watchdog_dev.c
>> b/drivers/watchdog/watchdog_dev.c
>> index 6aaefba..b519257 100644
>> --- a/drivers/watchdog/watchdog_dev.c
>> +++ b/drivers/watchdog/watchdog_dev.c
>> @@ -218,6 +218,38 @@ out_timeout:
>> }
>>
>> /*
>> + * watchdog_set_pretimeout: set the watchdog timer pretimeout
>> + * @wddev: the watchdog device to set the timeout for
>> + * @pretimeout: pretimeout to set in seconds
>> + */
>> +
>> +static int watchdog_set_pretimeout(struct watchdog_device *wddev,
>> + unsigned int pretimeout)
>> +{
>> + int err;
>> +
>> + if (!wddev->ops->set_pretimeout ||
>> + !(wddev->info->options & WDIOF_PRETIMEOUT))
>> + return -EOPNOTSUPP;
>> +
>> + if (watchdog_pretimeout_invalid(wddev, pretimeout))
>> + return -EINVAL;
>> +
>> + mutex_lock(&wddev->lock);
>> +
>> + if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
>> + err = -ENODEV;
>> + goto out_pretimeout;
>> + }
>> +
>> + err = wddev->ops->set_pretimeout(wddev, pretimeout);
>> +
>> +out_pretimeout:
>> + mutex_unlock(&wddev->lock);
>> + return err;
>> +}
>> +
>> +/*
>> * watchdog_get_timeleft: wrapper to get the time left before a
>> reboot
>> * @wddev: the watchdog device to get the remaining time from
>> * @timeleft: the time that's left
>> @@ -388,6 +420,22 @@ static long watchdog_ioctl(struct file *file,
>> unsigned int cmd,
>> if (wdd->timeout == 0)
>> return -EOPNOTSUPP;
>> return put_user(wdd->timeout, p);
>> + case WDIOC_SETPRETIMEOUT:
>> + if (get_user(val, p))
>> + return -EFAULT;
>> + err = watchdog_set_pretimeout(wdd, val);
>> + if (err < 0)
>> + return err;
>> + /* If the watchdog is active then we send a keepalive ping
>> + * to make sure that the watchdog keep's running (and if
>
>
> s/keep's/keeps/
Great thanks, typo
>
>> + * possible that it takes the new timeout) */
>
>
> Please use the common multi-line comment style (that it isn't used above is
> not
> an argument).
yes, my bad, will fixed .
>
>
>> + watchdog_ping(wdd);
>> + /* Fall */
>> + case WDIOC_GETPRETIMEOUT:
>> + /* timeout == 0 means that we don't use the pretimeout */
>> + if (wdd->pretimeout == 0)
>> + return -EOPNOTSUPP;
>> + return put_user(wdd->pretimeout, p);
>> case WDIOC_GETTIMELEFT:
>> err = watchdog_get_timeleft(wdd, &val);
>> if (err)
>> diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
>> index a746bf5..f0a3c5b 100644
>> --- a/include/linux/watchdog.h
>> +++ b/include/linux/watchdog.h
>> @@ -25,6 +25,7 @@ struct watchdog_device;
>> * @ping: The routine that sends a keepalive ping to the watchdog
>> device.
>> * @status: The routine that shows the status of the watchdog device.
>> * @set_timeout:The routine for setting the watchdog devices timeout
>> value.
>> + * @set_pretimeout:The routine for setting the watchdog devices
>> pretimeout value
>> * @get_timeleft:The routine that get's the time that's left before a
>> reset.
>> * @ref: The ref operation for dyn. allocated watchdog_device
>> structs
>> * @unref: The unref operation for dyn. allocated watchdog_device
>> structs
>> @@ -44,6 +45,7 @@ struct watchdog_ops {
>> int (*ping)(struct watchdog_device *);
>> unsigned int (*status)(struct watchdog_device *);
>> int (*set_timeout)(struct watchdog_device *, unsigned int);
>> + int (*set_pretimeout)(struct watchdog_device *, unsigned int);
>> unsigned int (*get_timeleft)(struct watchdog_device *);
>> void (*ref)(struct watchdog_device *);
>> void (*unref)(struct watchdog_device *);
>> @@ -62,6 +64,9 @@ struct watchdog_ops {
>> * @timeout: The watchdog devices timeout value.
>> * @min_timeout:The watchdog devices minimum timeout value.
>> * @max_timeout:The watchdog devices maximum timeout value.
>> + * @pretimeout: The watchdog devices pretimeout value.
>> + * @min_pretimeout:The watchdog devices minimum pretimeout value.
>> + * @max_pretimeout:The watchdog devices maximum pretimeout value.
>> * @driver-data:Pointer to the drivers private data.
>> * @lock: Lock for watchdog core internal use only.
>> * @status: Field that contains the devices internal status bits.
>> @@ -86,6 +91,9 @@ struct watchdog_device {
>> unsigned int timeout;
>> unsigned int min_timeout;
>> unsigned int max_timeout;
>> + unsigned int pretimeout;
>> + unsigned int min_pretimeout;
>> + unsigned int max_pretimeout;
>> void *driver_data;
>> struct mutex lock;
>> unsigned long status;
>> @@ -120,6 +128,14 @@ static inline bool watchdog_timeout_invalid(struct
>> watchdog_device *wdd, unsigne
>> (t < wdd->min_timeout || t > wdd->max_timeout));
>> }
>>
>> +/* 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));
>> +}
>> +
>> /* Use the following functions to manipulate watchdog driver specific
>> data */
>> static inline void watchdog_set_drvdata(struct watchdog_device *wdd,
>> void *data)
>> {
>> @@ -134,6 +150,9 @@ static inline void *watchdog_get_drvdata(struct
>> watchdog_device *wdd)
>> /* drivers/watchdog/watchdog_core.c */
>> extern int watchdog_init_timeout(struct watchdog_device *wdd,
>> unsigned int timeout_parm, struct device
>> *dev);
>> +extern int watchdog_init_pretimeout(struct watchdog_device *wdd,
>> + unsigned int pretimeout_parm,
>> + struct device *dev);
>
>
> Please drop the 'extern'. Guess it may be time to clean up the watchdog core
> code ;-).
yes, you are right, but in different patchset ??
>
> 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,
Shanghai,China 200021
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