gianfar: Fix race between gfar_error() and gfar_start_xmit()

gfar_error() can arrive at the middle of gfar_start_xmit() processing,
and so it can trigger transfers of BDs that we don't yet expect to
be transmitted.

Fix this by locking the tx queues in gfar_error().

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index a5b0038a8d98..fde430a0b84b 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -2943,14 +2943,22 @@ static irqreturn_t gfar_error(int irq, void *grp_id)
                 if (events & IEVENT_CRL)
                         dev->stats.tx_aborted_errors++;
                 if (events & IEVENT_XFUN) {
+                        unsigned long flags;
+
                         if (netif_msg_tx_err(priv))
                                 printk(KERN_DEBUG "%s: TX FIFO underrun, "
                                        "packet dropped.\n", dev->name);
                         dev->stats.tx_dropped++;
                         priv->extra_stats.tx_underrun++;
 
+                        local_irq_save(flags);
+                        lock_tx_qs(priv);
+
                         /* Reactivate the Tx Queues */
                         gfar_write(&regs->tstat, gfargrp->tstat);
+
+                        unlock_tx_qs(priv);
+                        local_irq_restore(flags);
                 }
                 if (netif_msg_tx_err(priv))
                         printk(KERN_DEBUG "%s: Transmit Error\n", dev->name);