diff options
| author | David Woodhouse <dwmw2@infradead.org> | 2012-04-08 10:01:44 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-04-13 13:06:47 -0400 |
| commit | 9a5d2bd99e0dfe9a31b3c160073ac445ba3d773f (patch) | |
| tree | e91d28ce1852c8a7016065ee2184dd2531d56892 | |
| parent | 1716a96101c49186bb0b8491922fd3e69030235f (diff) | |
| download | linux-3.10-9a5d2bd99e0dfe9a31b3c160073ac445ba3d773f.tar.gz linux-3.10-9a5d2bd99e0dfe9a31b3c160073ac445ba3d773f.tar.bz2 linux-3.10-9a5d2bd99e0dfe9a31b3c160073ac445ba3d773f.zip | |
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>
| -rw-r--r-- | drivers/net/ppp/ppp_generic.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index 33f8c51968b..21d7151fb0a 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; outf: @@ -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; ppp_xmit_lock(ppp); 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)) netif_wake_queue(ppp->dev); - ret = 1; - } + else + netif_stop_queue(ppp->dev); } ppp_xmit_unlock(ppp); - return ret; } static inline struct sk_buff * |