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Subject[PATCH] tty: synclink_gt: unwind actions in error path of net device open
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Zhengchao Shao <shaozhengchao@huawei.com> identified by inspection bugs in the error path of hdlcdev_open() in synclink_gt.c

The function did not fully unwind actions in the error path. The use of try_module_get()/module_put() is unnecessary, potentially hazardous and is removed. The synclink_gt driver is already pinned any point the net device is registered, a requirement for calling this entry point.

The call hdlc_open() to init the generic HDLC layer is moved to after driver level init/checks and proper rollback of previous actions is added. This is a more sensible ordering as the most common error paths are at the driver level and the driver level rollbacks require less processing than hdlc_open()/hdlc_close().

This has been tested with supported hardware.

Signed-off-by:Paul Fulghum <paulkf@microgate.com>

diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index 25e9befdda3a..72b76cdde534 100644
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -1433,16 +1433,8 @@ static int hdlcdev_open(struct net_device *dev)
int rc;
unsigned long flags;

- if (!try_module_get(THIS_MODULE))
- return -EBUSY;
-
DBGINFO(("%s hdlcdev_open\n", dev->name));

- /* generic HDLC layer open processing */
- rc = hdlc_open(dev);
- if (rc)
- return rc;
-
/* arbitrate between network and tty opens */
spin_lock_irqsave(&info->netlock, flags);
if (info->port.count != 0 || info->netcount != 0) {
@@ -1461,6 +1453,16 @@ static int hdlcdev_open(struct net_device *dev)
return rc;
}

+ /* generic HDLC layer open processing */
+ rc = hdlc_open(dev);
+ if (rc) {
+ shutdown(info);
+ spin_lock_irqsave(&info->netlock, flags);
+ info->netcount = 0;
+ spin_unlock_irqrestore(&info->netlock, flags);
+ return rc;
+ }
+
/* assert RTS and DTR, apply hardware settings */
info->signals |= SerialSignal_RTS | SerialSignal_DTR;
program_hw(info);
@@ -1506,7 +1508,6 @@ static int hdlcdev_close(struct net_device *dev)
info->netcount=0;
spin_unlock_irqrestore(&info->netlock, flags);

- module_put(THIS_MODULE);
return 0;
}

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