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if_awg: avoid hole in the rx ring buffer when mbuf allocation fails

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Use a spare dma map when attempting to map a new mbuf on the rx path.
If the mbuf allocation fails or the dma map loading for the new mbuf fails just reuse the old mbuf
and increase the drop counter.

Submitted by:	Guy Yur <guyyur@gmail.com>
Differential Revision:	https://reviews.freebsd.org/D12538
This commit is contained in:
Emmanuel Vadot 2017-11-18 21:08:18 +00:00
parent 337c6940a9
commit bd9063297c
1 changed files with 92 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

167
sys/arm/allwinner/if_awg.c
View File

@ -179,6 +179,7 @@ struct awg_rxring {
bus_addr_t desc_ring_paddr;
bus_dma_tag_t buf_tag;
struct awg_bufmap buf_map[RX_DESC_COUNT];
bus_dmamap_t buf_spare_map;
u_int cur;
};
@ -519,24 +520,45 @@ awg_setup_rxdesc(struct awg_softc *sc, int index, bus_addr_t paddr)
sc->rx.desc_ring[index].addr = htole32((uint32_t)paddr);
sc->rx.desc_ring[index].size = htole32(size);
sc->rx.desc_ring[index].next =
htole32(sc->rx.desc_ring_paddr + DESC_OFF(RX_NEXT(index)));
sc->rx.desc_ring[index].status = htole32(status);
}
static int
awg_setup_rxbuf(struct awg_softc *sc, int index, struct mbuf *m)
static void
awg_reuse_rxdesc(struct awg_softc *sc, int index)
{
bus_dma_segment_t seg;
int error, nsegs;
sc->rx.desc_ring[index].status = htole32(RX_DESC_CTL);
}
static int
awg_newbuf_rx(struct awg_softc *sc, int index)
{
struct mbuf *m;
bus_dma_segment_t seg;
bus_dmamap_t map;
int nsegs;
m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
if (m == NULL)
return (ENOBUFS);
m->m_pkthdr.len = m->m_len = m->m_ext.ext_size;
m_adj(m, ETHER_ALIGN);
error = bus_dmamap_load_mbuf_sg(sc->rx.buf_tag,
sc->rx.buf_map[index].map, m, &seg, &nsegs, 0);
if (error != 0)
return (error);
if (bus_dmamap_load_mbuf_sg(sc->rx.buf_tag, sc->rx.buf_spare_map,
m, &seg, &nsegs, BUS_DMA_NOWAIT) != 0) {
m_freem(m);
return (ENOBUFS);
}
if (sc->rx.buf_map[index].mbuf != NULL) {
bus_dmamap_sync(sc->rx.buf_tag, sc->rx.buf_map[index].map,
BUS_DMASYNC_POSTREAD);
bus_dmamap_unload(sc->rx.buf_tag, sc->rx.buf_map[index].map);
}
map = sc->rx.buf_map[index].map;
sc->rx.buf_map[index].map = sc->rx.buf_spare_map;
sc->rx.buf_spare_map = map;
bus_dmamap_sync(sc->rx.buf_tag, sc->rx.buf_map[index].map,
BUS_DMASYNC_PREREAD);
@ -546,18 +568,6 @@ awg_setup_rxbuf(struct awg_softc *sc, int index, struct mbuf *m)
return (0);
}
static struct mbuf *
awg_alloc_mbufcl(struct awg_softc *sc)
{
struct mbuf *m;
m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
if (m != NULL)
m->m_pkthdr.len = m->m_len = m->m_ext.ext_size;
return (m);
}
static void
awg_start_locked(struct awg_softc *sc)
{
@ -840,7 +850,7 @@ static int
awg_rxintr(struct awg_softc *sc)
{
if_t ifp;
struct mbuf *m, *m0, *mh, *mt;
struct mbuf *m, *mh, *mt;
int error, index, len, cnt, npkt;
uint32_t status;
@ -857,61 +867,62 @@ awg_rxintr(struct awg_softc *sc)
if ((status & RX_DESC_CTL) != 0)
break;
bus_dmamap_sync(sc->rx.buf_tag, sc->rx.buf_map[index].map,
BUS_DMASYNC_POSTREAD);
bus_dmamap_unload(sc->rx.buf_tag, sc->rx.buf_map[index].map);
len = (status & RX_FRM_LEN) >> RX_FRM_LEN_SHIFT;
if (len != 0) {
m = sc->rx.buf_map[index].mbuf;
m->m_pkthdr.rcvif = ifp;
m->m_pkthdr.len = len;
m->m_len = len;
if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
if ((if_getcapenable(ifp) & IFCAP_RXCSUM) != 0 &&
(status & RX_FRM_TYPE) != 0) {
m->m_pkthdr.csum_flags = CSUM_IP_CHECKED;
if ((status & RX_HEADER_ERR) == 0)
m->m_pkthdr.csum_flags |= CSUM_IP_VALID;
if ((status & RX_PAYLOAD_ERR) == 0) {
m->m_pkthdr.csum_flags |=
CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
m->m_pkthdr.csum_data = 0xffff;
}
}
m->m_nextpkt = NULL;
if (mh == NULL)
mh = m;
else
mt->m_nextpkt = m;
mt = m;
++cnt;
++npkt;
if (cnt == awg_rx_batch) {
AWG_UNLOCK(sc);
if_input(ifp, mh);
AWG_LOCK(sc);
mh = mt = NULL;
cnt = 0;
}
if (len == 0) {
if ((status & (RX_NO_ENOUGH_BUF_ERR | RX_OVERFLOW_ERR)) != 0)
if_inc_counter(ifp, IFCOUNTER_IERRORS, 1);
awg_reuse_rxdesc(sc, index);
continue;
}
if ((m0 = awg_alloc_mbufcl(sc)) != NULL) {
error = awg_setup_rxbuf(sc, index, m0);
if (error != 0) {
/* XXX hole in RX ring */
}
} else
m = sc->rx.buf_map[index].mbuf;
error = awg_newbuf_rx(sc, index);
if (error != 0) {
if_inc_counter(ifp, IFCOUNTER_IQDROPS, 1);
awg_reuse_rxdesc(sc, index);
continue;
}
m->m_pkthdr.rcvif = ifp;
m->m_pkthdr.len = len;
m->m_len = len;
if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
if ((if_getcapenable(ifp) & IFCAP_RXCSUM) != 0 &&
(status & RX_FRM_TYPE) != 0) {
m->m_pkthdr.csum_flags = CSUM_IP_CHECKED;
if ((status & RX_HEADER_ERR) == 0)
m->m_pkthdr.csum_flags |= CSUM_IP_VALID;
if ((status & RX_PAYLOAD_ERR) == 0) {
m->m_pkthdr.csum_flags |=
CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
m->m_pkthdr.csum_data = 0xffff;
}
}
m->m_nextpkt = NULL;
if (mh == NULL)
mh = m;
else
mt->m_nextpkt = m;
mt = m;
++cnt;
++npkt;
if (cnt == awg_rx_batch) {
AWG_UNLOCK(sc);
if_input(ifp, mh);
AWG_LOCK(sc);
mh = mt = NULL;
cnt = 0;
}
}
if (index != sc->rx.cur) {
bus_dmamap_sync(sc->rx.desc_tag, sc->rx.desc_map,
BUS_DMASYNC_PREWRITE);
BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
}
if (mh != NULL) {
@ -1500,7 +1511,6 @@ static int
awg_setup_dma(device_t dev)
{
struct awg_softc *sc;
struct mbuf *m;
int error, i;
sc = device_get_softc(dev);
@ -1615,18 +1625,25 @@ awg_setup_dma(device_t dev)
return (error);
}
error = bus_dmamap_create(sc->rx.buf_tag, 0, &sc->rx.buf_spare_map);
if (error != 0) {
device_printf(dev,
"cannot create RX buffer spare map\n");
return (error);
}
for (i = 0; i < RX_DESC_COUNT; i++) {
sc->rx.desc_ring[i].next =
htole32(sc->rx.desc_ring_paddr + DESC_OFF(RX_NEXT(i)));
error = bus_dmamap_create(sc->rx.buf_tag, 0,
&sc->rx.buf_map[i].map);
if (error != 0) {
device_printf(dev, "cannot create RX buffer map\n");
return (error);
}
if ((m = awg_alloc_mbufcl(sc)) == NULL) {
device_printf(dev, "cannot allocate RX mbuf\n");
return (ENOMEM);
}
error = awg_setup_rxbuf(sc, i, m);
sc->rx.buf_map[i].mbuf = NULL;
error = awg_newbuf_rx(sc, i);
if (error != 0) {
device_printf(dev, "cannot create RX buffer\n");
return (error);