Overhaul Rx path to recover from mbuf cluster allocation failure.
o Create one more spare DMA map for Rx handler to recover from
bus_dmamap_load_mbuf_sg(9) failure.
o Make sure to update status bit in Rx descriptors even if we failed
to allocate a new buffer. Previously it resulted in stuck condition
and em_handle_rxtx task took up all available CPU cycles.
o Don't blindly unload DMA map. Reuse loaded DMA map if received
packet has errors. This would speed up Rx processing a bit under
heavy load as it does not need to reload DMA map in case of error.
(bus_dmamap_load_mbuf_sg(9) is the most expensive call in driver
context.)
o Update if_iqdrops counter if it can't allocate a mbuf cluster.
With this change it's now possible to see queue dropped packets
with netstat(1).
o Update mbuf_cluster_failed counter if fixup code failed to
allocate mbuf header.
o Return ENOBUFS instead of ENOMEM in case of Rx fixup failure.
o Make adapter->lmp NULL in case of Rx fixup failure. Strictly
specking it's not necessary for correct operation but it makes
the intention clear.
o Remove now unused dropped_pkts member in softc.
With these changes em(4) should survive mbuf cluster allocation
failure on Rx path.
Reviewed by: pdeuskar, glebius (with improvements)
This commit is contained in:
Pyun YongHyeon
parent
1ad7bca7e9
commit
f1909c6f53
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=161266
@ -236,7 +236,7 @@ static void em_disable_promisc(struct adapter *);
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static void em_set_multi(struct adapter *);
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static void em_print_hw_stats(struct adapter *);
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static void em_update_link_status(struct adapter *);
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static int em_get_buf(int i, struct adapter *, struct mbuf *);
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static int em_get_buf(struct adapter *, int);
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static void em_enable_vlans(struct adapter *);
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static void em_disable_vlans(struct adapter *);
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static int em_encap(struct adapter *, struct mbuf **);
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@ -2803,45 +2803,49 @@ em_txeof(struct adapter *adapter)
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*
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**********************************************************************/
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static int
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em_get_buf(int i, struct adapter *adapter, struct mbuf *mp)
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em_get_buf(struct adapter *adapter, int i)
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{
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struct mbuf *m;
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bus_dma_segment_t segs[1];
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bus_dmamap_t map;
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struct em_buffer *rx_buffer;
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int error, nsegs;
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if (mp == NULL) {
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mp = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
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if (mp == NULL) {
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adapter->mbuf_cluster_failed++;
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return (ENOBUFS);
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}
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mp->m_len = mp->m_pkthdr.len = MCLBYTES;
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} else {
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mp->m_len = mp->m_pkthdr.len = MCLBYTES;
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mp->m_data = mp->m_ext.ext_buf;
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mp->m_next = NULL;
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m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
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if (m == NULL) {
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adapter->mbuf_cluster_failed++;
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return (ENOBUFS);
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}
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m->m_len = m->m_pkthdr.len = MCLBYTES;
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if (adapter->hw.max_frame_size <= (MCLBYTES - ETHER_ALIGN))
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m_adj(mp, ETHER_ALIGN);
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rx_buffer = &adapter->rx_buffer_area[i];
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m_adj(m, ETHER_ALIGN);
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/*
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* Using memory from the mbuf cluster pool, invoke the
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* bus_dma machinery to arrange the memory mapping.
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*/
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error = bus_dmamap_load_mbuf_sg(adapter->rxtag, rx_buffer->map,
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mp, segs, &nsegs, 0);
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error = bus_dmamap_load_mbuf_sg(adapter->rxtag, adapter->rx_sparemap,
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m, segs, &nsegs, BUS_DMA_NOWAIT);
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if (error != 0) {
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m_free(mp);
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m_free(m);
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return (error);
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}
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/* If nsegs is wrong then the stack is corrupt. */
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KASSERT(nsegs == 1, ("Too many segments returned!"));
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rx_buffer->m_head = mp;
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adapter->rx_desc_base[i].buffer_addr = htole64(segs[0].ds_addr);
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rx_buffer = &adapter->rx_buffer_area[i];
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if (rx_buffer->m_head != NULL)
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bus_dmamap_unload(adapter->rxtag, rx_buffer->map);
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map = rx_buffer->map;
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rx_buffer->map = adapter->rx_sparemap;
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adapter->rx_sparemap = map;
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bus_dmamap_sync(adapter->rxtag, rx_buffer->map, BUS_DMASYNC_PREREAD);
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rx_buffer->m_head = m;
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adapter->rx_desc_base[i].buffer_addr = htole64(segs[0].ds_addr);
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/* Zero out the receive descriptors status. */
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adapter->rx_desc_base[i].status = 0;
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return (0);
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}
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@ -2888,6 +2892,13 @@ em_allocate_receive_structures(struct adapter *adapter)
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goto fail;
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}
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error = bus_dmamap_create(adapter->rxtag, BUS_DMA_NOWAIT,
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&adapter->rx_sparemap);
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if (error) {
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device_printf(dev, "%s: bus_dmamap_create failed: %d\n",
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__func__, error);
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goto fail;
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}
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rx_buffer = adapter->rx_buffer_area;
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for (i = 0; i < adapter->num_rx_desc; i++, rx_buffer++) {
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error = bus_dmamap_create(adapter->rxtag, BUS_DMA_NOWAIT,
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@ -2900,7 +2911,7 @@ em_allocate_receive_structures(struct adapter *adapter)
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}
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for (i = 0; i < adapter->num_rx_desc; i++) {
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error = em_get_buf(i, adapter, NULL);
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error = em_get_buf(adapter, i);
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if (error)
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goto fail;
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}
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@ -3035,6 +3046,10 @@ em_free_receive_structures(struct adapter *adapter)
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INIT_DEBUGOUT("free_receive_structures: begin");
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if (adapter->rx_sparemap) {
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bus_dmamap_destroy(adapter->rxtag, adapter->rx_sparemap);
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adapter->rx_sparemap = NULL;
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}
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if (adapter->rx_buffer_area != NULL) {
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rx_buffer = adapter->rx_buffer_area;
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for (i = 0; i < adapter->num_rx_desc; i++, rx_buffer++) {
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@ -3103,10 +3118,12 @@ em_rxeof(struct adapter *adapter, int count)
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struct mbuf *m = NULL;
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mp = adapter->rx_buffer_area[i].m_head;
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/*
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* Can't defer bus_dmamap_sync(9) because TBI_ACCEPT
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* needs to access the last received byte in the mbuf.
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*/
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bus_dmamap_sync(adapter->rxtag, adapter->rx_buffer_area[i].map,
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BUS_DMASYNC_POSTREAD);
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bus_dmamap_unload(adapter->rxtag,
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adapter->rx_buffer_area[i].map);
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accept_frame = 1;
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prev_len_adj = 0;
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@ -3145,14 +3162,9 @@ em_rxeof(struct adapter *adapter, int count)
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}
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if (accept_frame) {
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if (em_get_buf(i, adapter, NULL) == ENOBUFS) {
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adapter->dropped_pkts++;
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em_get_buf(i, adapter, mp);
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if (adapter->fmp != NULL)
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m_freem(adapter->fmp);
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adapter->fmp = NULL;
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adapter->lmp = NULL;
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break;
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if (em_get_buf(adapter, i) != 0) {
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ifp->if_iqdrops++;
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goto discard;
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}
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/* Assign correct length to the current fragment */
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@ -3203,16 +3215,25 @@ em_rxeof(struct adapter *adapter, int count)
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adapter->lmp = NULL;
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}
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} else {
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adapter->dropped_pkts++;
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em_get_buf(i, adapter, mp);
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if (adapter->fmp != NULL)
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ifp->if_ierrors++;
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discard:
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/* Reuse loaded DMA map and just update mbuf chain */
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mp = adapter->rx_buffer_area[i].m_head;
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mp->m_len = mp->m_pkthdr.len = MCLBYTES;
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mp->m_data = mp->m_ext.ext_buf;
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mp->m_next = NULL;
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if (adapter->hw.max_frame_size <= (MCLBYTES - ETHER_ALIGN))
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m_adj(mp, ETHER_ALIGN);
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if (adapter->fmp != NULL) {
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m_freem(adapter->fmp);
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adapter->fmp = NULL;
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adapter->lmp = NULL;
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adapter->fmp = NULL;
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adapter->lmp = NULL;
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}
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/* Zero out the receive descriptors status. */
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adapter->rx_desc_base[i].status = 0;
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m = NULL;
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}
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/* Zero out the receive descriptors status. */
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current_desc->status = 0;
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bus_dmamap_sync(adapter->rxdma.dma_tag, adapter->rxdma.dma_map,
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BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
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@ -3281,10 +3302,12 @@ em_fixup_rx(struct adapter *adapter)
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n->m_next = m;
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adapter->fmp = n;
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} else {
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adapter->dropped_pkts++;
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adapter->ifp->if_iqdrops++;
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adapter->mbuf_alloc_failed++;
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m_freem(adapter->fmp);
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adapter->fmp = NULL;
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error = ENOMEM;
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adapter->lmp = NULL;
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error = ENOBUFS;
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}
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}
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@ -3556,9 +3579,9 @@ em_update_stats_counters(struct adapter *adapter)
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ifp->if_collisions = adapter->stats.colc;
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/* Rx Errors */
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ifp->if_ierrors = adapter->dropped_pkts + adapter->stats.rxerrc +
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adapter->stats.crcerrs + adapter->stats.algnerrc + adapter->stats.ruc +
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adapter->stats.roc + adapter->stats.mpc + adapter->stats.cexterr;
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ifp->if_ierrors = adapter->stats.rxerrc + adapter->stats.crcerrs +
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adapter->stats.algnerrc + adapter->stats.ruc + adapter->stats.roc +
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adapter->stats.mpc + adapter->stats.cexterr;
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/* Tx Errors */
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ifp->if_oerrors = adapter->stats.ecol + adapter->stats.latecol +
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@ -3611,8 +3634,6 @@ em_print_debug_info(struct adapter *adapter)
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adapter->mbuf_alloc_failed);
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device_printf(dev, "Std mbuf cluster failed = %ld\n",
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adapter->mbuf_cluster_failed);
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device_printf(dev, "Driver dropped packets = %ld\n",
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adapter->dropped_pkts);
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}
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static void
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@ -324,13 +324,13 @@ struct adapter {
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int rx_process_limit;
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struct em_buffer *rx_buffer_area;
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bus_dma_tag_t rxtag;
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bus_dmamap_t rx_sparemap;
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/* First/last mbuf pointers, for collecting multisegment RX packets. */
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struct mbuf *fmp;
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struct mbuf *lmp;
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/* Misc stats maintained by the driver */
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unsigned long dropped_pkts;
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unsigned long mbuf_alloc_failed;
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unsigned long mbuf_cluster_failed;
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unsigned long no_tx_desc_avail1;
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