Re: [PATCH] xen/manage: unwind partial shutdown watcher setup on error

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

Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on v7.0]
[cannot apply to xen-tip/linux-next linus/master next-20260420]
[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/zhaoguohan-kylinos-cn/xen-manage-unwind-partial-shutdown-watcher-setup-on-error/20260416-185003
base:   v7.0
patch link:    https://lore.kernel.org/r/20260407022443.12971-1-zhaoguohan%40kylinos.cn
patch subject: [PATCH] xen/manage: unwind partial shutdown watcher setup on error
config: arm64-randconfig-002-20260421 (https://download.01.org/0day-ci/archive/20260421/202604211801.rqptlYaS-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260421/202604211801.rqptlYaS-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/202604211801.rqptlYaS-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/xen/manage.c: In function 'setup_shutdown_watcher':
>> drivers/xen/manage.c:380:1: warning: label 'err_unregister_shutdown' defined but not used [-Wunused-label]
     380 | err_unregister_shutdown:
         | ^~~~~~~~~~~~~~~~~~~~~~~
   drivers/xen/manage.c: In function 'shutdown_event':
   drivers/xen/manage.c:357:60: warning: '%s' directive output may be truncated writing up to 71 bytes into a region of size 12 [-Wformat-truncation=]
     357 |                 snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
         |                                                            ^~
   In function 'setup_shutdown_watcher',
       inlined from 'shutdown_event' at drivers/xen/manage.c:389:2:
   drivers/xen/manage.c:357:17: note: 'snprintf' output between 9 and 80 bytes into a destination of size 20
     357 |                 snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     358 |                          shutdown_handlers[idx].command);
         |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/err_unregister_shutdown +380 drivers/xen/manage.c

   353	
   354		for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
   355			if (!shutdown_handlers[idx].flag)
   356				continue;
   357			snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
   358				 shutdown_handlers[idx].command);
   359			err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
   360			if (err) {
   361				pr_err("%s: Error %d writing %s\n", __func__,
   362					err, node);
   363				goto err_remove_features;
   364			}
   365		}
   366	
   367		return 0;
   368	
   369	err_remove_features:
   370		while (--idx >= 0) {
   371			if (!shutdown_handlers[idx].flag)
   372				continue;
   373			snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
   374				 shutdown_handlers[idx].command);
   375			xenbus_rm(XBT_NIL, "control", node);
   376		}
   377	#ifdef CONFIG_MAGIC_SYSRQ
   378		unregister_xenbus_watch(&sysrq_watch);
   379	#endif
 > 380	err_unregister_shutdown:
   381		unregister_xenbus_watch(&shutdown_watch);
   382		return err;
   383	}
   384	

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