any inputs?
On Sun, Jun 2, 2013 at 3:56 PM, anish singh <anish198519851985@xxxxxxxxx> wrote:
> On Sun, Jun 2, 2013 at 3:43 PM, anish kumar <anish198519851985@xxxxxxxxx> wrote:
>> Certain watchdog drivers use a timer to keep kicking the watchdog at
>> a rate of 0.5s (HZ/2) untill userspace times out.They do this as
>> we can't guarantee that watchdog will be pinged fast enough
>> for all system loads, especially if timeout is configured for
>> less than or equal to 1 second(basically small values).
>>
>> As suggested by Wim Van Sebroeck & Guenter Roeck we should
>> add this functionality of individual watchdog drivers in the core
>> watchdog core.
>>
>> Signed-off-by: anish kumar <anish198519851985@xxxxxxxxx>
>> ---
>> drivers/watchdog/watchdog_dev.c | 34 +++++++++++++++++++++++++++++-----
>> include/linux/watchdog.h | 1 +
>> 2 files changed, 30 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
>> index faf4e18..0305803 100644
>> --- a/drivers/watchdog/watchdog_dev.c
>> +++ b/drivers/watchdog/watchdog_dev.c
>> @@ -41,9 +41,14 @@
>> #include <linux/miscdevice.h> /* For handling misc devices */
>> #include <linux/init.h> /* For __init/__exit/... */
>> #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
>> +#include <linux/timer.h>
>> +#include <linux/jiffies.h>
>>
>> #include "watchdog_core.h"
>>
>> +/* Timer heartbeat (500ms) */
>> +#define WDT_TIMEOUT (HZ/2) /* should this be sysfs? */
>> +
>> /* the dev_t structure to store the dynamically allocated watchdog devices */
>> static dev_t watchdog_devt;
>> /* the watchdog device behind /dev/watchdog */
>> @@ -73,16 +78,33 @@ static int watchdog_ping(struct watchdog_device *wddev)
> I think watchdog_ping function prototype should be changed as nowhere
> we use the return value.
>> if (!watchdog_active(wddev))
>> goto out_ping;
>>
>> - if (wddev->ops->ping)
>> - err = wddev->ops->ping(wddev); /* ping the watchdog */
>> - else
>> - err = wddev->ops->start(wddev); /* restart watchdog */
>> + /* should we check ping interval value i.e. timeout value
>> + if it is less than certain threshold then only we
>> + should add this logic of periodic pinging? */
>> + if (time_before(jiffies, (unsigned long)wddev->timeout)) {
>> + if (wddev->ops->ping)
>> + err = wddev->ops->ping(wddev);/* ping the watchdog */
>> + else
>> + err = wddev->ops->start(wddev);/* restart watchdog */
>> + mod_timer(&wddev->timer, jiffies + WDT_TIMEOUT);
>> + } else {
>> + /*
>> + *what we should when we find out that userspace
>> + *has timed out?
>> + **/
>> + }
>>
>> out_ping:
>> mutex_unlock(&wddev->lock);
>> return err;
>> }
>>
>> +static void watchdog_ping_wrapper(unsigned long priv)
> if we change the watchdog_ping api then we don't need this wrapper.
>> +{
>> + struct watchdog_device *wdd = (void *)priv;
>> + watchdog_ping(wdd);
>> +}
>> +
>> /*
>> * watchdog_start: wrapper to start the watchdog.
>> * @wddev: the watchdog device to start
>> @@ -109,7 +131,8 @@ static int watchdog_start(struct watchdog_device *wddev)
>> err = wddev->ops->start(wddev);
>> if (err == 0)
>> set_bit(WDOG_ACTIVE, &wddev->status);
>> -
>> +
>> + mod_timer(&wddev->timer, jiffies + WDT_TIMEOUT);
>> out_start:
>> mutex_unlock(&wddev->lock);
>> return err;
>> @@ -552,6 +575,7 @@ int watchdog_dev_register(struct watchdog_device *watchdog)
>> old_wdd = NULL;
>> }
>> }
>> + setup_timer(&watchdog->timer, 0, (long)watchdog_ping_wrapper);
>> return err;
>> }
>>
>> diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
>> index 2a3038e..e5f18f7 100644
>> --- a/include/linux/watchdog.h
>> +++ b/include/linux/watchdog.h
>> @@ -84,6 +84,7 @@ struct watchdog_device {
>> const struct watchdog_ops *ops;
>> unsigned int bootstatus;
>> unsigned int timeout;
>> + struct timer_list timer;
> should we use hrtimer? or timer would do?
>> unsigned int min_timeout;
>> unsigned int max_timeout;
>> void *driver_data;
>> --
>> 1.7.10.4
>>
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