myx_intr should be able to run without a lock, except in teh situation where
are bringing an interface down.
this interlock was done by serialising the changes myx_down and myx_intr needed
to do with a mutex, but for the many millions and billions of interrupts you
get when you're actually using the interface, this is an annoying overhead.
this plays tricks to avoid the mutex.
it works for me, but im throwing it out so someone else can try and hopefully
break it.
Index: if_myx.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/if_myx.c,v
retrieving revision 1.82
diff -u -p -r1.82 if_myx.c
--- if_myx.c 15 Aug 2015 01:17:01 -0000 1.82
+++ if_myx.c 1 Sep 2015 05:09:34 -0000
@@ -32,6 +32,7 @@
#include <sys/pool.h>
#include <sys/timeout.h>
#include <sys/device.h>
+#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/atomic.h>
@@ -123,7 +124,6 @@ struct myx_softc {
struct myx_dmamem sc_sts_dma;
volatile struct myx_status *sc_sts;
- struct mutex sc_sts_mtx;
int sc_intx;
void *sc_irqh;
@@ -226,26 +226,6 @@ void myx_tx_free(struct myx_softc *);
void myx_refill(void *);
-static inline void
-myx_sts_enter(struct myx_softc *sc)
-{
- bus_dmamap_t map = sc->sc_sts_dma.mxm_map;
-
- mtx_enter(&sc->sc_sts_mtx);
- bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
- BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);
-}
-
-static inline void
-myx_sts_leave(struct myx_softc *sc)
-{
- bus_dmamap_t map = sc->sc_sts_dma.mxm_map;
-
- bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
- BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
- mtx_leave(&sc->sc_sts_mtx);
-}
-
struct cfdriver myx_cd = {
NULL, "myx", DV_IFNET
};
@@ -285,8 +265,6 @@ myx_attach(struct device *parent, struct
timeout_set(&sc->sc_rx_ring[MYX_RXBIG].mrr_refill, myx_refill,
&sc->sc_rx_ring[MYX_RXBIG]);
- mtx_init(&sc->sc_sts_mtx, IPL_NET);
-
/* Map the PCI memory space */
memtype = pci_mapreg_type(sc->sc_pc, sc->sc_tag, MYXBAR0);
if (pci_mapreg_map(pa, MYXBAR0, memtype, BUS_SPACE_MAP_PREFETCHABLE,
@@ -889,6 +867,7 @@ void
myx_media_status(struct ifnet *ifp, struct ifmediareq *imr)
{
struct myx_softc *sc = (struct myx_softc *)ifp->if_softc;
+ bus_dmamap_t map = sc->sc_sts_dma.mxm_map;
u_int32_t sts;
imr->ifm_active = IFM_ETHER | IFM_AUTO;
@@ -897,9 +876,11 @@ myx_media_status(struct ifnet *ifp, stru
return;
}
- myx_sts_enter(sc);
+ bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
+ BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);
sts = sc->sc_sts->ms_linkstate;
- myx_sts_leave(sc);
+ bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
+ BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
myx_link_state(sc, sts);
@@ -1220,9 +1201,7 @@ myx_up(struct myx_softc *sc)
goto empty_rx_ring_big;
}
- mtx_enter(&sc->sc_sts_mtx);
sc->sc_state = MYX_S_RUNNING;
- mtx_leave(&sc->sc_sts_mtx);
if (myx_cmd(sc, MYXCMD_SET_IFUP, &mc, NULL) != 0) {
printf("%s: failed to start the device\n", DEVNAME(sc));
@@ -1349,24 +1328,28 @@ myx_down(struct myx_softc *sc)
struct ifnet *ifp = &sc->sc_ac.ac_if;
volatile struct myx_status *sts = sc->sc_sts;
bus_dmamap_t map = sc->sc_sts_dma.mxm_map;
+ struct sleep_state sls;
struct myx_cmd mc;
int s;
int ring;
- myx_sts_enter(sc);
+ bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
+ BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);
sc->sc_linkdown = sts->ms_linkdown;
+ bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
+ BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
+
sc->sc_state = MYX_S_DOWN;
+ membar_producer();
memset(&mc, 0, sizeof(mc));
(void)myx_cmd(sc, MYXCMD_SET_IFDOWN, &mc, NULL);
- bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
- BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
- while (sc->sc_state != MYX_S_OFF)
- msleep(sts, &sc->sc_sts_mtx, 0, "myxdown", 0);
- bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
- BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);
- mtx_leave(&sc->sc_sts_mtx);
+ while (sc->sc_state != MYX_S_OFF) {
+ sleep_setup(&sls, sts, PWAIT, "myxdown");
+ membar_consumer();
+ sleep_finish(&sls, sc->sc_state != MYX_S_OFF);
+ }
s = splnet();
if (ifp->if_link_state != LINK_STATE_UNKNOWN) {
@@ -1604,23 +1587,22 @@ myx_intr(void *arg)
struct myx_softc *sc = (struct myx_softc *)arg;
struct ifnet *ifp = &sc->sc_ac.ac_if;
volatile struct myx_status *sts = sc->sc_sts;
- enum myx_state state = MYX_S_RUNNING;
+ enum myx_state state;
bus_dmamap_t map = sc->sc_sts_dma.mxm_map;
- u_int32_t data, link = 0xffffffff;
+ u_int32_t data, start;
u_int8_t valid = 0;
- mtx_enter(&sc->sc_sts_mtx);
- if (sc->sc_state == MYX_S_OFF) {
- mtx_leave(&sc->sc_sts_mtx);
+ state = sc->sc_state;
+ if (state == MYX_S_OFF)
return (0);
- }
bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);
valid = sts->ms_isvalid;
if (valid == 0x0) {
- myx_sts_leave(sc);
+ bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
+ BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
return (0);
}
@@ -1639,15 +1621,6 @@ myx_intr(void *arg)
BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
} while (sts->ms_isvalid);
- if (sts->ms_statusupdated) {
- link = sts->ms_linkstate;
-
- if (sc->sc_state == MYX_S_DOWN &&
- sc->sc_linkdown != sts->ms_linkdown)
- state = MYX_S_DOWN;
- }
- myx_sts_leave(sc);
-
data = betoh32(data);
if (data != sc->sc_tx_count)
myx_txeof(sc, data);
@@ -1662,23 +1635,29 @@ myx_intr(void *arg)
bus_space_write_raw_region_4(sc->sc_memt, sc->sc_memh,
sc->sc_irqclaimoff + sizeof(data), &data, sizeof(data));
- if (state == MYX_S_DOWN) {
- /* myx_down is waiting for us */
- mtx_enter(&sc->sc_sts_mtx);
- sc->sc_state = MYX_S_OFF;
- wakeup(sts);
- mtx_leave(&sc->sc_sts_mtx);
+ start = ISSET(ifp->if_flags, IFF_OACTIVE);
- return (1);
+ if (sts->ms_statusupdated) {
+ if (state == MYX_S_DOWN &&
+ sc->sc_linkdown != sts->ms_linkdown) {
+ sc->sc_state = MYX_S_OFF;
+ membar_producer();
+ wakeup(sts);
+ start = 0;
+ } else {
+ data = sts->ms_linkstate;
+ if (data != 0xffffffff) {
+ KERNEL_LOCK();
+ myx_link_state(sc, data);
+ KERNEL_UNLOCK();
+ }
+ }
}
- if (link != 0xffffffff) {
- KERNEL_LOCK();
- myx_link_state(sc, link);
- KERNEL_UNLOCK();
- }
+ bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
+ BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
- if (ISSET(ifp->if_flags, IFF_OACTIVE)) {
+ if (start) {
KERNEL_LOCK();
CLR(ifp->if_flags, IFF_OACTIVE);
myx_start(ifp);
