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SubjectRe: [PATCH] tty: synclink_gt: unwind actions in error path of net device open
On Tue, Nov 15, 2022 at 10:21:14AM -0800, Paul Fulghum wrote:
> hdlcdev_open() in synclink_gt.c 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.
>
> Suggested-by: Zhengchao Shao <shaozhengchao@huawei.com>
> 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;
> }
>


Hi,

This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him
a patch that has triggered this response. He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created. Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

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Please read the section entitled "The canonical patch format" in the
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If you wish to discuss this problem further, or you have questions about
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thanks,

greg k-h's patch email bot

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