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Subject[PATCH net] drivers/net/wan/x25_asy: Correct the ndo_open and ndo_stop functions
Date
1.
Move the lapb_register/lapb_unregister calls into the ndo_open/ndo_stop
functions in x25_asy_netdev_ops.
This makes the LAPB protocol start/stop when the network interface
starts/stops. When the network interface is down, the LAPB protocol
shouldn't be running and the LAPB module shoudn't be generating control
frames.

2.
Move netif_start_queue/netif_stop_queue into the ndo_open/ndo_stop
functions in x25_asy_netdev_ops.
This makes the TX queue start/stop when the network interface
starts/stops.

3.
The x25_asy_close function was originally used as the ndo_stop function.
However, I think when stopping the interface we shouldn't do the things
that this function does (except netif_stop_queue).
1) We shouldn't clear TTY_DO_WRITE_WAKEUP and set sl->xleft to 0,
because this may cause the transmission of the last frame before
stopping to be incomplete.
2) We shouldn't set sl->rcount to 0,
because if we stop the interface and quickly start it again,
the first frame we receive could be incomplete.
So I moved it to make it be called in x25_asy_close_tty (when closing
the TTY line discipline) instead. (This also makes the code look better
because x25_asy_open is called in x25_asy_open_tty.)

Cc: Martin Schiller <ms@dev.tdt.de>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
---
drivers/net/wan/x25_asy.c | 42 +++++++++++++++++++++++----------------
1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index 7ee980575208..88a73ce6d9f4 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -464,7 +464,6 @@ static int x25_asy_open(struct net_device *dev)
{
struct x25_asy *sl = netdev_priv(dev);
unsigned long len;
- int err;

if (sl->tty == NULL)
return -ENODEV;
@@ -490,14 +489,7 @@ static int x25_asy_open(struct net_device *dev)
sl->xleft = 0;
sl->flags &= (1 << SLF_INUSE); /* Clear ESCAPE & ERROR flags */

- netif_start_queue(dev);
-
- /*
- * Now attach LAPB
- */
- err = lapb_register(dev, &x25_asy_callbacks);
- if (err == LAPB_OK)
- return 0;
+ return 0;

/* Cleanup */
kfree(sl->xbuff);
@@ -519,7 +511,6 @@ static int x25_asy_close(struct net_device *dev)
if (sl->tty)
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);

- netif_stop_queue(dev);
sl->rcount = 0;
sl->xleft = 0;
spin_unlock(&sl->lock);
@@ -604,7 +595,6 @@ static int x25_asy_open_tty(struct tty_struct *tty)
static void x25_asy_close_tty(struct tty_struct *tty)
{
struct x25_asy *sl = tty->disc_data;
- int err;

/* First make sure we're connected. */
if (!sl || sl->magic != X25_ASY_MAGIC)
@@ -615,11 +605,7 @@ static void x25_asy_close_tty(struct tty_struct *tty)
dev_close(sl->dev);
rtnl_unlock();

- err = lapb_unregister(sl->dev);
- if (err != LAPB_OK)
- pr_err("%s: lapb_unregister error: %d\n",
- __func__, err);
-
+ x25_asy_close(sl->dev);
tty->disc_data = NULL;
sl->tty = NULL;
x25_asy_free(sl);
@@ -722,15 +708,37 @@ static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,

static int x25_asy_open_dev(struct net_device *dev)
{
+ int err;
struct x25_asy *sl = netdev_priv(dev);
if (sl->tty == NULL)
return -ENODEV;
+
+ err = lapb_register(dev, &x25_asy_callbacks);
+ if (err != LAPB_OK)
+ return -ENOMEM;
+
+ netif_start_queue(dev);
+
+ return 0;
+}
+
+static int x25_asy_close_dev(struct net_device *dev)
+{
+ int err;
+
+ netif_stop_queue(dev);
+
+ err = lapb_unregister(dev);
+ if (err != LAPB_OK)
+ pr_err("%s: lapb_unregister error: %d\n",
+ __func__, err);
+
return 0;
}

static const struct net_device_ops x25_asy_netdev_ops = {
.ndo_open = x25_asy_open_dev,
- .ndo_stop = x25_asy_close,
+ .ndo_stop = x25_asy_close_dev,
.ndo_start_xmit = x25_asy_xmit,
.ndo_tx_timeout = x25_asy_timeout,
.ndo_change_mtu = x25_asy_change_mtu,
--
2.25.1
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