Various fixups to locking:

- Remove a lot of superfluous locking during attach.  There is no need
  to lock access to the driver until some other thread has a way of getting
  to it.  For ethernet drivers the other ways include registering an
  interrupt handler via bus_setup_intr(), calling ether_ifattach() to hook
  into the network stack, and kicking off a callout-driven timer via
  callout_reset().
- Use callout_* rather than timeout/untimeout.
- Break out of xl_rxeof() if IFF_DRV_RUNNING is clear after ifp->if_input
  returns to handle the case where the interface was stopped while we were
  passing a packet up the stack.  Don't call xl_rxeof() in xl_rxeof_task()
  unless IFF_DRV_RUNNING is set.  With these fixes in place, any
  outstanding task will gracefully terminate as soon as it gets a chance to
  run after the interface has been stopped via xl_stop().  As a result,
  taskqueue_drain() is no longer required in xl_stop().  The task is still
  drained in detach() however to make sure that detach() can safely destroy
  the driver mutex at the end of the function.
- Lock the driver lock in the ifmedia callouts and don't lock across
  ifmedia_ioctl() in xl_ioctl().

Note: glebius came up with most of (3) as well independently.  I took a
rather roundabout way of arriving at the same conclusion.

MFC after:	3 days

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/pci/if_xlreg.h b/sys/pci/if_xlreg.h
index d1d2e8f..f999b71 100644
--- a/sys/pci/if_xlreg.h
+++ b/sys/pci/if_xlreg.h
@@ -601,7 +601,7 @@ struct xl_softc {
 	int			xl_if_flags;
 	struct xl_list_data	xl_ldata;
 	struct xl_chain_data	xl_cdata;
-	struct callout_handle	xl_stat_ch;
+	struct callout		xl_stat_callout;
 	int			xl_flags;
 	struct resource		*xl_fres;
 	bus_space_handle_t	xl_fhandle;