moxart_mac_start_xmit() doesn't care where tx_tail is, tx_head can catch and pass tx_tail, which is bad because moxart_tx_finished() isn't guaranteed to catch up on freeing resources from tx_tail.
Add a check in moxart_mac_start_xmit(), exit to make sure tx_head never passes tx_tail. Move tx_head and place tx_tail within spinlock, avoiding read-write race that could happen when interrupts hit at the wrong moment. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=99451 Signed-off-by: Jonas Jensen <jonas.jen...@gmail.com> --- Notes: Applies to next-20150604 drivers/net/ethernet/moxa/moxart_ether.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c index becbb5f..e0af86c 100644 --- a/drivers/net/ethernet/moxa/moxart_ether.c +++ b/drivers/net/ethernet/moxa/moxart_ether.c @@ -25,6 +25,7 @@ #include <linux/of_irq.h> #include <linux/crc32.h> #include <linux/crc32c.h> +#include <linux/circ_buf.h> #include "moxart_ether.h" @@ -312,13 +313,22 @@ static int moxart_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev) struct moxart_mac_priv_t *priv = netdev_priv(ndev); void __iomem *desc; unsigned int len; - unsigned int tx_head = priv->tx_head; + unsigned int tx_head, tx_tail; u32 txdes1; int ret = NETDEV_TX_BUSY; + spin_lock_irq(&priv->txlock); + + tx_head = priv->tx_head; + tx_tail = priv->tx_tail; + desc = priv->tx_desc_base + (TX_REG_DESC_SIZE * tx_head); - spin_lock_irq(&priv->txlock); + if (CIRC_SPACE(tx_head, tx_tail, TX_DESC_NUM) == 0) { + priv->stats.tx_dropped++; + goto out_unlock; + } + if (readl(desc + TX_REG_OFFSET_DESC0) & TX_DESC0_DMA_OWN) { net_dbg_ratelimited("no TX space for packet\n"); priv->stats.tx_dropped++; -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
