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net: moxa: fix TX overrun memory leak 

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 <jonas.jensen@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jonas Jensen 2017-03-28 12:12:38 +02:00 committed by David S. Miller
parent af109a2cf6
commit c2b341a620
2 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/net/ethernet/moxa/moxart_ether.c
View File

@ -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++;

1
drivers/net/ethernet/moxa/moxart_ether.h
View File

@ -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)