From: Finn Thain fthain@telegraphics.com.au
commit eaabfd19b2c787bbe88dc32424b9a43d67293422 upstream.
The while loop in sonic_rx() traverses the rx descriptor ring. It stops when it reaches a descriptor that the SONIC has not used. Each iteration advances the EOL flag so the SONIC can keep using more descriptors. Therefore, the while loop has no definite termination condition.
The algorithm described in the National Semiconductor literature is quite different. It consumes descriptors up to the one with its EOL flag set (which will also have its "in use" flag set). All freed descriptors are then returned to the ring at once, by adjusting the EOL flags (and link pointers).
Adopt the algorithm from datasheet as it's simpler, terminates quickly and avoids a lot of pointless descriptor EOL flag changes.
Fixes: efcce839360f ("[PATCH] macsonic/jazzsonic network drivers update") Tested-by: Stan Johnson userm57@yahoo.com Signed-off-by: Finn Thain fthain@telegraphics.com.au Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/ethernet/natsemi/sonic.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)
--- a/drivers/net/ethernet/natsemi/sonic.c +++ b/drivers/net/ethernet/natsemi/sonic.c @@ -436,6 +436,7 @@ static void sonic_rx(struct net_device * struct sonic_local *lp = netdev_priv(dev); int status; int entry = lp->cur_rx; + int prev_entry = lp->eol_rx;
while (sonic_rda_get(dev, entry, SONIC_RD_IN_USE) == 0) { struct sk_buff *used_skb; @@ -516,13 +517,21 @@ static void sonic_rx(struct net_device * /* * give back the descriptor */ - sonic_rda_put(dev, entry, SONIC_RD_LINK, - sonic_rda_get(dev, entry, SONIC_RD_LINK) | SONIC_EOL); sonic_rda_put(dev, entry, SONIC_RD_IN_USE, 1); - sonic_rda_put(dev, lp->eol_rx, SONIC_RD_LINK, - sonic_rda_get(dev, lp->eol_rx, SONIC_RD_LINK) & ~SONIC_EOL); - lp->eol_rx = entry; - lp->cur_rx = entry = (entry + 1) & SONIC_RDS_MASK; + + prev_entry = entry; + entry = (entry + 1) & SONIC_RDS_MASK; + } + + lp->cur_rx = entry; + + if (prev_entry != lp->eol_rx) { + /* Advance the EOL flag to put descriptors back into service */ + sonic_rda_put(dev, prev_entry, SONIC_RD_LINK, SONIC_EOL | + sonic_rda_get(dev, prev_entry, SONIC_RD_LINK)); + sonic_rda_put(dev, lp->eol_rx, SONIC_RD_LINK, ~SONIC_EOL & + sonic_rda_get(dev, lp->eol_rx, SONIC_RD_LINK)); + lp->eol_rx = prev_entry; } /* * If any worth-while packets have been received, netif_rx()