sunvnet: improve error handling when a remote crashes

If a remote machine crashes while there are pending transmit buffers, the
sunvnet driver reallocates the ring descriptors giving us enries that have
state VIO_DESC_FREE but also an allocated skb. This results in a BUG_ON()
call when the remote reboots and we reach that point in the ring.

This patch:

1) clears pending tx packets in the ring on port reset
2) changes a BUG_ON() to a pr_warn() when a remote host has given us an invalid
	descriptor state
3) collapses multiple active buffer frees in a ring to a single message per
	ring and adds the device name and remote MAC address

This fixes the particular problem of not cleaning up pending buffers on a
reset, but also prevents us from crashing if the remote handles descriptors
out of order or sets an unexpected state for a descriptor.

Signed-off-by: David L Stevens <david.stevens@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 28 deletions

diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index fe044f31708e..2b719ccd6e7c 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c
@@ -50,6 +50,7 @@ MODULE_VERSION(DRV_MODULE_VERSION);
 #define VNET_MAX_RETRIES        10
 
 static int __vnet_tx_trigger(struct vnet_port *port, u32 start);
+static void vnet_port_reset(struct vnet_port *port);
 
 /* Ordered from largest major to lowest */
 static struct vio_version vnet_versions[] = {
@@ -736,9 +737,7 @@ ldc_ctrl:
                 vio_link_state_change(vio, event);
 
                 if (event == LDC_EVENT_RESET) {
-                        port->rmtu = 0;
-                        port->tso = true;
-                        port->tsolen = 0;
+                        vnet_port_reset(port);
                         vio_port_up(vio);
                 }
                 port->rx_event = 0;
@@ -934,36 +933,36 @@ static struct sk_buff *vnet_clean_tx_ring(struct vnet_port *port,
 
         *pending = 0;
 
-        txi = dr->prod-1;
-        if (txi < 0)
-                txi = VNET_TX_RING_SIZE-1;
-
+        txi = dr->prod;
         for (i = 0; i < VNET_TX_RING_SIZE; ++i) {
                 struct vio_net_desc *d;
 
-                d = vio_dring_entry(dr, txi);
-
-                if (d->hdr.state == VIO_DESC_DONE) {
-                        if (port->tx_bufs[txi].skb) {
-                                BUG_ON(port->tx_bufs[txi].skb->next);
+                --txi;
+                if (txi < 0)
+                        txi = VNET_TX_RING_SIZE-1;
 
-                                port->tx_bufs[txi].skb->next = skb;
-                                skb = port->tx_bufs[txi].skb;
-                                port->tx_bufs[txi].skb = NULL;
+                d = vio_dring_entry(dr, txi);
 
-                                ldc_unmap(port->vio.lp,
-                                          port->tx_bufs[txi].cookies,
-                                          port->tx_bufs[txi].ncookies);
-                        }
-                        d->hdr.state = VIO_DESC_FREE;
-                } else if (d->hdr.state == VIO_DESC_READY) {
+                if (d->hdr.state == VIO_DESC_READY) {
                         (*pending)++;
-                } else if (d->hdr.state == VIO_DESC_FREE) {
-                        break;
+                        continue;
                 }
-                --txi;
-                if (txi < 0)
-                        txi = VNET_TX_RING_SIZE-1;
+                if (port->tx_bufs[txi].skb) {
+                        if (d->hdr.state != VIO_DESC_DONE)
+                                pr_notice("invalid ring buffer state %d\n",
+                                          d->hdr.state);
+                        BUG_ON(port->tx_bufs[txi].skb->next);
+
+                        port->tx_bufs[txi].skb->next = skb;
+                        skb = port->tx_bufs[txi].skb;
+                        port->tx_bufs[txi].skb = NULL;
+
+                        ldc_unmap(port->vio.lp,
+                                  port->tx_bufs[txi].cookies,
+                                  port->tx_bufs[txi].ncookies);
+                } else if (d->hdr.state == VIO_DESC_FREE)
+                        break;
+                d->hdr.state = VIO_DESC_FREE;
         }
         return skb;
 }
@@ -1649,8 +1648,6 @@ static void vnet_port_free_tx_bufs(struct vnet_port *port)
                         continue;
 
                 d = vio_dring_entry(dr, i);
-                if (d->hdr.state == VIO_DESC_READY)
-                        pr_warn("active transmit buffers freed\n");
 
                 ldc_unmap(port->vio.lp,
                           port->tx_bufs[i].cookies,
@@ -1669,6 +1666,15 @@ static void vnet_port_free_tx_bufs(struct vnet_port *port)
         dr->ncookies = 0;
 }
 
+static void vnet_port_reset(struct vnet_port *port)
+{
+        del_timer(&port->clean_timer);
+        vnet_port_free_tx_bufs(port);
+        port->rmtu = 0;
+        port->tso = true;
+        port->tsolen = 0;
+}
+
 static int vnet_port_alloc_tx_ring(struct vnet_port *port)
 {
         struct vio_dring_state *dr;