Re: [PATCH] USB: HCD: Fix URB giveback issue in tasklet function

[kernel test robot <lkp@intel.com>]

Hi Weitao,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on usb/usb-testing]
[also build test WARNING on linus/master v5.19-rc7 next-20220721]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Weitao-Wang/USB-HCD-Fix-URB-giveback-issue-in-tasklet-function/20220721-144208
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
config: i386-defconfig (https://download.01.org/0day-ci/archive/20220721/202207212305.50JoL7V2-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/302398ba5a76bb39957bad7a6a8cb9d0429cd43a
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Weitao-Wang/USB-HCD-Fix-URB-giveback-issue-in-tasklet-function/20220721-144208
        git checkout 302398ba5a76bb39957bad7a6a8cb9d0429cd43a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/usb/core/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/usb/core/hcd.c: In function 'usb_giveback_urb_bh':
>> drivers/usb/core/hcd.c:1694:2: warning: label 'restart' defined but not used [-Wunused-label]
    1694 |  restart:
         |  ^~~~~~~


vim +/restart +1694 drivers/usb/core/hcd.c

94dfd7edfd5c9b Ming Lei    2013-07-03  1686  
e71ea55a5b6f91 Allen Pais  2020-08-17  1687  static void usb_giveback_urb_bh(struct tasklet_struct *t)
94dfd7edfd5c9b Ming Lei    2013-07-03  1688  {
e71ea55a5b6f91 Allen Pais  2020-08-17  1689  	struct giveback_urb_bh *bh = from_tasklet(bh, t, bh);
94dfd7edfd5c9b Ming Lei    2013-07-03  1690  	struct list_head local_list;
94dfd7edfd5c9b Ming Lei    2013-07-03  1691  
94dfd7edfd5c9b Ming Lei    2013-07-03  1692  	spin_lock_irq(&bh->lock);
94dfd7edfd5c9b Ming Lei    2013-07-03  1693  	bh->running = true;
94dfd7edfd5c9b Ming Lei    2013-07-03 @1694   restart:
94dfd7edfd5c9b Ming Lei    2013-07-03  1695  	list_replace_init(&bh->head, &local_list);
94dfd7edfd5c9b Ming Lei    2013-07-03  1696  	spin_unlock_irq(&bh->lock);
94dfd7edfd5c9b Ming Lei    2013-07-03  1697  
94dfd7edfd5c9b Ming Lei    2013-07-03  1698  	while (!list_empty(&local_list)) {
94dfd7edfd5c9b Ming Lei    2013-07-03  1699  		struct urb *urb;
94dfd7edfd5c9b Ming Lei    2013-07-03  1700  
94dfd7edfd5c9b Ming Lei    2013-07-03  1701  		urb = list_entry(local_list.next, struct urb, urb_list);
94dfd7edfd5c9b Ming Lei    2013-07-03  1702  		list_del_init(&urb->urb_list);
c7ccde6eac6d3c Alan Stern  2013-09-03  1703  		bh->completing_ep = urb->ep;
94dfd7edfd5c9b Ming Lei    2013-07-03  1704  		__usb_hcd_giveback_urb(urb);
c7ccde6eac6d3c Alan Stern  2013-09-03  1705  		bh->completing_ep = NULL;
94dfd7edfd5c9b Ming Lei    2013-07-03  1706  	}
94dfd7edfd5c9b Ming Lei    2013-07-03  1707  
302398ba5a76bb Weitao Wang 2022-07-21  1708  	/* giveback new URBs next time to prevent this function from
302398ba5a76bb Weitao Wang 2022-07-21  1709  	 * not exiting for a long time.
302398ba5a76bb Weitao Wang 2022-07-21  1710  	 */
94dfd7edfd5c9b Ming Lei    2013-07-03  1711  	spin_lock_irq(&bh->lock);
302398ba5a76bb Weitao Wang 2022-07-21  1712  	if (!list_empty(&bh->head)) {
302398ba5a76bb Weitao Wang 2022-07-21  1713  		if (bh->hi_priority)
302398ba5a76bb Weitao Wang 2022-07-21  1714  			tasklet_hi_schedule(&bh->bh);
302398ba5a76bb Weitao Wang 2022-07-21  1715  		else
302398ba5a76bb Weitao Wang 2022-07-21  1716  			tasklet_schedule(&bh->bh);
302398ba5a76bb Weitao Wang 2022-07-21  1717  	}
94dfd7edfd5c9b Ming Lei    2013-07-03  1718  	bh->running = false;
94dfd7edfd5c9b Ming Lei    2013-07-03  1719  	spin_unlock_irq(&bh->lock);
94dfd7edfd5c9b Ming Lei    2013-07-03  1720  }
94dfd7edfd5c9b Ming Lei    2013-07-03  1721  

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