Re: [RFC PATCH 2/2] netconsole: Defer netpoll cleanup to avoid lock release during list traversal

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

Hi Breno,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]
[also build test ERROR on net/main linus/master next-20240719]
[cannot apply to horms-ipvs/master v6.10]
[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/Breno-Leitao/netpoll-extract-core-of-netpoll_cleanup/20240719-024801
base:   net-next/main
patch link:    https://lore.kernel.org/r/20240718184311.3950526-3-leitao%40debian.org
patch subject: [RFC PATCH 2/2] netconsole: Defer netpoll cleanup to avoid lock release during list traversal
config: i386-buildonly-randconfig-005-20240719 (https://download.01.org/0day-ci/archive/20240719/202407192328.P5nrBKoH-lkp@intel.com/config)
compiler: gcc-10 (Ubuntu 10.5.0-1ubuntu1) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240719/202407192328.P5nrBKoH-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202407192328.P5nrBKoH-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/net/netconsole.c: In function 'netconsole_netdev_event':
>> drivers/net/netconsole.c:1053:2: error: implicit declaration of function 'netconsole_process_cleanups_core' [-Werror=implicit-function-declaration]
    1053 |  netconsole_process_cleanups_core();
         |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/netconsole_process_cleanups_core +1053 drivers/net/netconsole.c

   996	
   997	/* Handle network interface device notifications */
   998	static int netconsole_netdev_event(struct notifier_block *this,
   999					   unsigned long event, void *ptr)
  1000	{
  1001		unsigned long flags;
  1002		struct netconsole_target *nt, *tmp;
  1003		struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  1004		bool stopped = false;
  1005	
  1006		if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
  1007		      event == NETDEV_RELEASE || event == NETDEV_JOIN))
  1008			goto done;
  1009	
  1010		mutex_lock(&target_cleanup_list_lock);
  1011		spin_lock_irqsave(&target_list_lock, flags);
  1012		list_for_each_entry_safe(nt, tmp, &target_list, list) {
  1013			netconsole_target_get(nt);
  1014			if (nt->np.dev == dev) {
  1015				switch (event) {
  1016				case NETDEV_CHANGENAME:
  1017					strscpy(nt->np.dev_name, dev->name, IFNAMSIZ);
  1018					break;
  1019				case NETDEV_RELEASE:
  1020				case NETDEV_JOIN:
  1021				case NETDEV_UNREGISTER:
  1022					nt->enabled = false;
  1023					list_move(&nt->list, &target_cleanup_list);
  1024					stopped = true;
  1025				}
  1026			}
  1027			netconsole_target_put(nt);
  1028		}
  1029		spin_unlock_irqrestore(&target_list_lock, flags);
  1030		mutex_unlock(&target_cleanup_list_lock);
  1031	
  1032		if (stopped) {
  1033			const char *msg = "had an event";
  1034	
  1035			switch (event) {
  1036			case NETDEV_UNREGISTER:
  1037				msg = "unregistered";
  1038				break;
  1039			case NETDEV_RELEASE:
  1040				msg = "released slaves";
  1041				break;
  1042			case NETDEV_JOIN:
  1043				msg = "is joining a master device";
  1044				break;
  1045			}
  1046			pr_info("network logging stopped on interface %s as it %s\n",
  1047				dev->name, msg);
  1048		}
  1049	
  1050		/* Process target_cleanup_list entries. By the end, target_cleanup_list
  1051		 * should be empty
  1052		 */
> 1053		netconsole_process_cleanups_core();
  1054	
  1055	done:
  1056		return NOTIFY_DONE;
  1057	}
  1058	

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https://github.com/intel/lkp-tests/wiki