Date: Fri, 12 Apr 2013 14:30:24 -0700
From: Guenter Roeck <linux@roeck-us.net>
To: Don Zickus <dzickus@redhat.com>
Cc: Dave Young <dyoung@redhat.com>, linux-watchdog@vger.kernel.org,
        kexec@lists.infradead.org, wim@iguana.be,
        LKML <linux-kernel@vger.kernel.org>, vgoyal@redhat.com
Subject: Re: [RFC PATCH] watchdog: Add hook for kicking in kdump path
Message-ID: <20130412213024.GA5812@roeck-us.net>
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 <20130409160757.GA27050@roeck-us.net>
 <20130410134039.GV79013@redhat.com>
 <20130410135123.GB15456@roeck-us.net>
 <20130410142055.GW79013@redhat.com>
 <20130410151041.GA6670@roeck-us.net>
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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 ?).

Guenter
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