On Fri, Apr 12, 2013 at 02:30:24PM -0700, Guenter Roeck wrote: > On Fri, Apr 12, 2013 at 05:16:27PM -0400, Don Zickus wrote: > > On Wed, Apr 10, 2013 at 08:10:41AM -0700, Guenter Roeck wrote: > > > > have no idea how to even find out if multiple watchdogs are open on the > > > > system. Is there a list I could walk? And with regard to 'watchdog is > > > > > > /* the dev_t structure to store the dynamically allocated watchdog devices */ > > > static dev_t watchdog_devt; > > > > > > One way to look up the allocated watchdogs might be to loop through all kobj > > > instances for the major device using kobj_lookup. Don't know if there is a > > > better way. > > > > Hmm, I got around to poking at this today and I am not sure kobj_lookup > > will work. Besides being surrounded with another mutex, I don't have > > access to the character device domain to pass to kobj_lookup. > > > > Perhaps I am not reading the code right, but I can't find a good way > > forward. > > > > The only other hack I can think of, is to embed a list object in the > > watchdog structure and list_add each new register'd watchdog. Then it > > would be trivial to walk the watchdog list. > > > After looking into it again, I agree. Maybe you can give it a try. At least > other options look even more complicated (eg creating a watchdog class ?). I looked at the watchdog class in watchdog_core.c. Even implemented class_for_each_device. But got stuck trying to figure out how to go from a struct device *dev to a struct watchdog_device. Then I realized in the bowels of class_for_each_device were spinlocks. :-( So I implemented an RCU list. It isn't the prettiest solution but it seems to work. I posted a V2 and realized I forgot to cc you on it. I apologize for that. :-( I hope you can find it, otherwise I can post a pointer to it. Cheers, Don
