path: root/drivers/net/ppp/ppp_generic.c
diff options
authorDavid Woodhouse <dwmw2@infradead.org>2012-04-08 10:01:44 +0000
committerDavid S. Miller <davem@davemloft.net>2012-04-13 13:06:47 -0400
commit9a5d2bd99e0dfe9a31b3c160073ac445ba3d773f (patch)
treee91d28ce1852c8a7016065ee2184dd2531d56892 /drivers/net/ppp/ppp_generic.c
parentipv6: fix problem with expired dst cache (diff)
ppp: Fix race condition with queue start/stop
Commit e675f0cc9a872fd152edc0c77acfed19bf28b81e ("ppp: Don't stop and restart queue on every TX packet") introduced a race condition which could leave the net queue stopped even when the channel is no longer busy. By calling netif_stop_queue() from ppp_start_xmit(), based on the return value from ppp_xmit_process() but *after* all the locks have been dropped, we could potentially do so *after* the channel has actually finished transmitting and attempted to re-wake the queue. Fix this by moving the netif_stop_queue() into ppp_xmit_process() under the xmit lock. I hadn't done this previously, because it gets called from other places than ppp_start_xmit(). But I now think it's the better option. The net queue *should* be stopped if the channel becomes congested due to writes from pppd, anyway. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ppp/ppp_generic.c')
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 33f8c51968b6..21d7151fb0ab 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -235,7 +235,7 @@ struct ppp_net {
/* Prototypes. */
static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
struct file *file, unsigned int cmd, unsigned long arg);
-static int ppp_xmit_process(struct ppp *ppp);
+static void ppp_xmit_process(struct ppp *ppp);
static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
static void ppp_push(struct ppp *ppp);
static void ppp_channel_push(struct channel *pch);
@@ -969,8 +969,7 @@ ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
put_unaligned_be16(proto, pp);
skb_queue_tail(&ppp->file.xq, skb);
- if (!ppp_xmit_process(ppp))
- netif_stop_queue(dev);
+ ppp_xmit_process(ppp);
return NETDEV_TX_OK;
@@ -1048,11 +1047,10 @@ static void ppp_setup(struct net_device *dev)
* Called to do any work queued up on the transmit side
* that can now be done.
-static int
+static void
ppp_xmit_process(struct ppp *ppp)
struct sk_buff *skb;
- int ret = 0;
if (!ppp->closing) {
@@ -1062,13 +1060,12 @@ ppp_xmit_process(struct ppp *ppp)
ppp_send_frame(ppp, skb);
/* If there's no work left to do, tell the core net
code that we can accept some more. */
- if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq)) {
+ if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
- ret = 1;
- }
+ else
+ netif_stop_queue(ppp->dev);
- return ret;
static inline struct sk_buff *