Convert ndis_spinlock to ndis_mtx and start using the sleepable

mtx interface for NDIS_LOCK/UNLOCK. This should result in less
CPU utilization on behalf of the ndis driver. Additionally, this
commit also fixes a potential LOR in the ndis_tick code, by
not locking inside the ndis_tick function, but instead delegating
that work to the helpers called through IoQueueWorkItem. The
way that this is currently set up for NDIS prevents us from
simply implementing a callout_init_mtx mechanism.

However, the helper functions that handle the various timeout
cases implement fine-grained locking using the spinlocks provided
by the NDIS-compat layer, and using the mtx that is added with
this commit. This leaves the following ndis_softc members operated
on in ndis_tick in an unlocked context:

  * ndis_hang_timer - Only modified outside of ndis_tick once, before
                      the first callout_reset to schedule ndis_tick
  * ifp->if_oerrors - Only incremented in two places, which should be
                      an atomic op
  * ndis_tx_timer   - Assigned to 5 (when guaranteed to be 0) or 0
                      (in txeof), to indicate to ndis_tick what to
                      do. This is the only member of which I was
                      suspicious for needing the NDIS_LOCK here. My
                      testing (and another's) have been fine so far.
  * ndis_stat_callout - Only uses a simple set of callout routines,
                        callout_reset only called by ndis_tick after
                        the initial reset, and then callout_drain is
                        used exactly once in shutdown code.

The benefit is that ndis_tick doesn't acquire NDIS_LOCK unless one of
the timeout conditions is flagged, and it still obeys the locking
order semantics that are dictated by the NDIS layer at the moment. I
have been investigating a more thorough s/spinlock/mtx/ of the NDIS
layer, but the simplest naive approach (replace KeAcquireSpinLock
with an mtx implementation) has anti-succeeded for me so far. This
is a good first step though.

Tested by:	onemda@gmail.com
Reviewed by:	current@, jhb, thompsa
Proposed by:	jhb

2 files changed, 5 insertions, 8 deletions

diff --git a/sys/dev/if_ndis/if_ndis.c b/sys/dev/if_ndis/if_ndis.c
index c4b7128..30600f4 100644
--- a/sys/dev/if_ndis/if_ndis.c
+++ b/sys/dev/if_ndis/if_ndis.c
@@ -533,7 +533,8 @@ ndis_attach(dev)
 
 	sc = device_get_softc(dev);
 
-	KeInitializeSpinLock(&sc->ndis_spinlock);
+	mtx_init(&sc->ndis_mtx, device_get_nameunit(dev), MTX_NETWORK_LOCK,
+	    MTX_DEF);
 	KeInitializeSpinLock(&sc->ndis_rxlock);
 	InitializeListHead(&sc->ndis_shlist);
 	callout_init(&sc->ndis_stat_callout, CALLOUT_MPSAFE);
@@ -1644,7 +1645,6 @@ ndis_tick(xsc)
 	struct ndis_softc	*sc;
 
 	sc = xsc;
-	NDIS_LOCK(sc);
 
 	if (sc->ndis_hang_timer && --sc->ndis_hang_timer == 0) {
 		IoQueueWorkItem(sc->ndis_tickitem,
@@ -1666,7 +1666,6 @@ ndis_tick(xsc)
 	}
 
 	callout_reset(&sc->ndis_stat_callout, hz, ndis_tick, sc);
-	NDIS_UNLOCK(sc);
 }
 
 static void
diff --git a/sys/dev/if_ndis/if_ndisvar.h b/sys/dev/if_ndis/if_ndisvar.h
index 61db134..868b5de 100644
--- a/sys/dev/if_ndis/if_ndisvar.h
+++ b/sys/dev/if_ndis/if_ndisvar.h
@@ -129,7 +129,7 @@ struct ndis_softc {
 	struct resource		*ndis_res_cm;	/* common mem (pccard) */
 	struct resource_list	ndis_rl;
 	int			ndis_rescnt;
-	kspin_lock		ndis_spinlock;
+	struct mtx		ndis_mtx;
 	uint8_t			ndis_irql;
 	device_t		ndis_dev;
 	int			ndis_unit;
@@ -185,7 +185,5 @@ struct ndis_softc {
 	int			ndis_hang_timer;
 };
 
-#define NDIS_LOCK(_sc)		KeAcquireSpinLock(&(_sc)->ndis_spinlock, \
-				    &(_sc)->ndis_irql);
-#define NDIS_UNLOCK(_sc)	KeReleaseSpinLock(&(_sc)->ndis_spinlock, \
-				    (_sc)->ndis_irql);
+#define NDIS_LOCK(_sc)		mtx_lock(&(_sc)->ndis_mtx)
+#define NDIS_UNLOCK(_sc)	mtx_unlock(&(_sc)->ndis_mtx)