svn commit: r191142 - head/sys/dev/mge

[Rafal Jaworowski]

Author: raj
Date: Thu Apr 16 11:38:06 2009
New Revision: 191142
URL: http://svn.freebsd.org/changeset/base/191142

Log:
  mge(4): fix two bugs, which were leading to crash/hang under very heavy
  network load.
  
  1. Leave the RX interrupt routine if there is no mbuf available.
  
  2. Properly initialize and track tx_desc_used_count counter so as not to
  leak mbuf while traversing used descriptors.
  
  Obtained from:        Semihalf

Modified:
  head/sys/dev/mge/if_mge.c

Modified: head/sys/dev/mge/if_mge.c
==============================================================================
--- head/sys/dev/mge/if_mge.c   Thu Apr 16 11:21:52 2009        (r191141)
+++ head/sys/dev/mge/if_mge.c   Thu Apr 16 11:38:06 2009        (r191142)
@@ -642,6 +642,7 @@ mge_attach(device_t dev)
        sc->tx_desc_curr = 0;
        sc->rx_desc_curr = 0;
        sc->tx_desc_used_idx = 0;
+       sc->tx_desc_used_count = 0;
 
        /* Configure defaults for interrupts coalescing */
        sc->rx_ic_time = 768;
@@ -899,6 +900,7 @@ mge_init_locked(void *arg)
        sc->tx_desc_curr = 0;
        sc->rx_desc_curr = 0;
        sc->tx_desc_used_idx = 0;
+       sc->tx_desc_used_count = 0;
 
        /* Enable RX descriptors */
        for (i = 0; i < MGE_RX_DESC_NUM; i++) {
@@ -1022,7 +1024,7 @@ mge_intr_rx_locked(struct mge_softc *sc,
 
        MGE_RECEIVE_LOCK_ASSERT(sc);
 
-       while(count != 0) {
+       while (count != 0) {
                dw = &sc->mge_rx_desc[sc->rx_desc_curr];
                bus_dmamap_sync(sc->mge_desc_dtag, dw->desc_dmap,
                    BUS_DMASYNC_POSTREAD);
@@ -1033,7 +1035,6 @@ mge_intr_rx_locked(struct mge_softc *sc,
                if ((status & MGE_DMA_OWNED) != 0)
                        break;
 
-               sc->rx_desc_curr = (++sc->rx_desc_curr % MGE_RX_DESC_NUM);
                if (dw->mge_desc->byte_count &&
                    ~(status & MGE_ERR_SUMMARY)) {
 
@@ -1044,6 +1045,10 @@ mge_intr_rx_locked(struct mge_softc *sc,
                            dw->mge_desc->byte_count - ETHER_CRC_LEN,
                            0, ifp, NULL);
 
+                       if (mb == NULL)
+                               /* Give up if no mbufs */
+                               break;
+
                        mb->m_len -= 2;
                        mb->m_pkthdr.len -= 2;
                        mb->m_data += 2;
@@ -1058,6 +1063,7 @@ mge_intr_rx_locked(struct mge_softc *sc,
 
                dw->mge_desc->byte_count = 0;
                dw->mge_desc->cmd_status = MGE_RX_ENABLE_INT | MGE_DMA_OWNED;
+               sc->rx_desc_curr = (++sc->rx_desc_curr % MGE_RX_DESC_NUM);
                bus_dmamap_sync(sc->mge_desc_dtag, dw->desc_dmap,
                    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
 
@@ -1514,7 +1520,8 @@ mge_stop(struct mge_softc *sc)
        MGE_WRITE(sc, MGE_RX_QUEUE_CMD, MGE_DISABLE_RXQ_ALL);
 
        /* Remove pending data from TX queue */
-       while (sc->tx_desc_used_idx < sc->tx_desc_curr) {
+       while (sc->tx_desc_used_idx != sc->tx_desc_curr &&
+           sc->tx_desc_used_count) {
                /* Get the descriptor */
                dw = &sc->mge_tx_desc[sc->tx_desc_used_idx];
                desc = dw->mge_desc;
@@ -1529,6 +1536,7 @@ mge_stop(struct mge_softc *sc)
 
                sc->tx_desc_used_idx = (++sc->tx_desc_used_idx) %
                    MGE_TX_DESC_NUM;
+               sc->tx_desc_used_count--;
 
                bus_dmamap_sync(sc->mge_tx_dtag, dw->buffer_dmap,
                    BUS_DMASYNC_POSTWRITE);
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