There's currently a diagnostic printk in relay_switch_subbuf() meant as
a warning if you accidentally try to log an event larger than the
sub-buffer size.

The problem is if this happens while logging from somewhere it's not
safe to be doing printks, such as in the scheduler, you can end up with
a deadlock.  This patch removes the warning from relay_switch_subbuf()
and instead prints some diagnostic info when the channel is closed.

Thanks to Mathieu Desnoyers for pointing out the problem and
suggesting a fix.

Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>