Re: [PATCH] Export current_is_keventd() for libphy

[Roland Dreier <rdreier@cisco.com>]

 > Ah.  The point is that the phy code doesn't want to flush _all_ pending
 > callbacks.  It only wants to flush its own one.  And its own one doesn't
 > take rtnl_lock().

OK, got it.  You're absolutely correct.

 > Maybe the lesson here is that flush_scheduled_work() is a bad function.
 > It should really be flush_this_work(struct work_struct *w).  That is in
 > fact what approximately 100% of the flush_scheduled_work() callers actually
 > want to do.

I think flush_this_work() runs into trouble if it means "make sure
everything up to <this work> has completed" because it still syncs
with everything before <this work>, which has the same risk of
deadlock.  And I'm not totally sure everyone who does
flush_scheduled_work() really means "cancel my work" -- they might mean
"finish up my work".

For example I would have to do some archeology to remember exactly
what I needed flush_scheduled_work() when I wrote drivers/infiniband/ulp/ipoib

 - R.