diff mbox series

tty: synclink_gt: unwind actions in error path of net device open

Message ID 2b501d50-6777-a34f-7373-6648ed418794@microgate.com
State New
Headers
Series tty: synclink_gt: unwind actions in error path of net device open |

Commit Message

Paul Fulghum Nov. 15, 2022, 6:21 p.m. UTC 
  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>

Comments

Greg KH Nov. 15, 2022, 6:48 p.m. UTC | #1 
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.

You are receiving this message because of the following common error(s)
as indicated below:

- Your patch is malformed (tabs converted to spaces, linewrapped, etc.)
  and can not be applied.  Please read the file,
  Documentation/email-clients.txt in order to fix this.

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/SubmittingPatches for what needs to be done
  here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot
diff mbox series

Patch

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;
  }