[PATCH v3] net: moxa: fix TX overrun memory leak
From: Jonas Jensen <hidden>
Date: 2017-03-28 10:13:24
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() stopping the queue at the
end of the circular buffer. Also add a check in moxart_tx_finished()
waking the queue if the buffer has TX_WAKE_THRESHOLD or more
free descriptors.
While we're at it, move spin_lock_irq() to happen before our
descriptor pointer is assigned in moxart_mac_start_xmit().
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=99451
Signed-off-by: Jonas Jensen <redacted>
---
Notes:
ChangeLog v2->v3:
- add wakeup threshold
ChangeLog v1->v2:
- stop queue instead of dropping frames
Applies to next-20170310
drivers/net/ethernet/moxa/moxart_ether.c | 20 ++++++++++++++++++--
drivers/net/ethernet/moxa/moxart_ether.h | 1 +
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c
index 06c9f41..6ad44be 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"
@@ -278,6 +279,13 @@ static int moxart_rx_poll(struct napi_struct *napi, int budget) return rx; } +static int moxart_tx_queue_space(struct net_device *ndev) +{ + struct moxart_mac_priv_t *priv = netdev_priv(ndev); + + return CIRC_SPACE(priv->tx_head, priv->tx_tail, TX_DESC_NUM); +} + static void moxart_tx_finished(struct net_device *ndev) { struct moxart_mac_priv_t *priv = netdev_priv(ndev);
@@ -297,6 +305,9 @@ static void moxart_tx_finished(struct net_device *ndev) tx_tail = TX_NEXT(tx_tail); } priv->tx_tail = tx_tail; + if (netif_queue_stopped(ndev) && + moxart_tx_queue_space(ndev) >= TX_WAKE_THRESHOLD) + netif_wake_queue(ndev); } static irqreturn_t moxart_mac_interrupt(int irq, void *dev_id)
@@ -324,13 +335,18 @@ static int moxart_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev) struct moxart_mac_priv_t *priv = netdev_priv(ndev); void *desc; unsigned int len; - unsigned int tx_head = priv->tx_head; + unsigned int tx_head; u32 txdes1; int ret = NETDEV_TX_BUSY; + spin_lock_irq(&priv->txlock); + + tx_head = priv->tx_head; desc = priv->tx_desc_base + (TX_REG_DESC_SIZE * tx_head); - spin_lock_irq(&priv->txlock); + if (moxart_tx_queue_space(ndev) == 1) + netif_stop_queue(ndev); + if (moxart_desc_read(desc + TX_REG_OFFSET_DESC0) & TX_DESC0_DMA_OWN) { net_dbg_ratelimited("no TX space for packet\n"); priv->stats.tx_dropped++;
diff --git a/drivers/net/ethernet/moxa/moxart_ether.h b/drivers/net/ethernet/moxa/moxart_ether.h
index 93a9563..afc32ec 100644
--- a/drivers/net/ethernet/moxa/moxart_ether.h
+++ b/drivers/net/ethernet/moxa/moxart_ether.h@@ -59,6 +59,7 @@ #define TX_NEXT(N) (((N) + 1) & (TX_DESC_NUM_MASK)) #define TX_BUF_SIZE 1600 #define TX_BUF_SIZE_MAX (TX_DESC1_BUF_SIZE_MASK+1) +#define TX_WAKE_THRESHOLD 16 #define RX_DESC_NUM 64 #define RX_DESC_NUM_MASK (RX_DESC_NUM-1)
--
1.8.2.1