usb: gadget: f_hid: tidy error handling in hidg_alloc

Unify error handling at the end of the function, reducing the risk of
missing something on one of the error paths.

Moving the increment of opts->refcnt later means there is no need to
decrement it on the error path and is safe as this is guarded by
opts->lock which is held for this entire section.

Tested-by: Lee Jones <lee@kernel.org>
Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Reviewed-by: Lee Jones <lee@kernel.org>
Signed-off-by: John Keeping <john@metanate.com>
Link: https://lore.kernel.org/r/20221122123523.3068034-4-john@metanate.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index 6be6009..a8da3b4 100644 (file)
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -1269,18 +1269,14 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi)
        opts = container_of(fi, struct f_hid_opts, func_inst);
 
        mutex_lock(&opts->lock);
-       ++opts->refcnt;
 
        device_initialize(&hidg->dev);
        hidg->dev.release = hidg_release;
        hidg->dev.class = hidg_class;
        hidg->dev.devt = MKDEV(major, opts->minor);
        ret = dev_set_name(&hidg->dev, "hidg%d", opts->minor);
-       if (ret) {
-               --opts->refcnt;
-               mutex_unlock(&opts->lock);
-               return ERR_PTR(ret);
-       }
+       if (ret)
+               goto err_unlock;
 
        hidg->bInterfaceSubClass = opts->subclass;
        hidg->bInterfaceProtocol = opts->protocol;
@@ -1291,14 +1287,13 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi)
                                                 opts->report_desc_length,
                                                 GFP_KERNEL);
                if (!hidg->report_desc) {
-                       put_device(&hidg->dev);
-                       --opts->refcnt;
-                       mutex_unlock(&opts->lock);
-                       return ERR_PTR(-ENOMEM);
+                       ret = -ENOMEM;
+                       goto err_put_device;
                }
        }
        hidg->use_out_ep = !opts->no_out_endpoint;
 
+       ++opts->refcnt;
        mutex_unlock(&opts->lock);
 
        hidg->func.name    = "hid";
@@ -1313,6 +1308,12 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi)
        hidg->qlen         = 4;
 
        return &hidg->func;
+
+err_put_device:
+       put_device(&hidg->dev);
+err_unlock:
+       mutex_unlock(&opts->lock);
+       return ERR_PTR(ret);
 }
 
 DECLARE_USB_FUNCTION_INIT(hid, hidg_alloc_inst, hidg_alloc);