Re: [PATCH] fix RTC_CLASS regression with PARISC

[David Miller <davem@davemloft.net>]

From: David Brownell <david-b@pacbell.net>
Date: Mon, 8 Sep 2008 17:55:25 -0700

> On Monday 08 September 2008, David Miller wrote:
> > From: David Brownell <david-b@pacbell.net>
> > Date: Mon, 8 Sep 2008 16:29:20 -0700
> > 
> > > That said, there's a bit of unresolved stuff around NTP hooks
> > > in the kernel.  Some patches are pending to let thtem work with
> > > the RTC framework -- where writing an RTC may need to sleep,
> > > for example because the RTC is on an I2C or SPI bus.  And
> > > then there's the discussion of whether that shouldn't all be
> > > handled by NTPD anyway, no special kernel support desired.
> > > Alessandro has opinions there.  ;)
> > 
> > My update_persistent_clock() on sparc64 is:
> > 
> > int update_persistent_clock(struct timespec now)
> > {
> > 	struct rtc_device *rtc = rtc_class_open("rtc0");
> 
> I'd be tempted to cache that ... notice how you never
> close it, too.  That will goof lots of refcounts...

Well if I cache it then we'll hold it forever and that's not
so nice right?

I'm going to put the missing rtc_close() in there for now to
fix the leak.

I'm happy to cache this if you think it's warranted, but then
this is like saying that the refcount doesn't matter :-)

> =============== CUT ON THE DOTTED LINE ==================
> Subject: ntp: let update_persistent_clock() sleep
> From: "Maciej W. Rozycki" <macro@linux-mips.org>

I see, as Paul mentioned this is needed for stuff like RTCs
behind I2C.

This change isn't in Linus's tree yet.