[linux-next:master 10231/11867] drivers/gpu/drm/xe/xe_configfs.c:282 lookup_engine_info() error: we previously assumed 'mask' could be null (see line 278)

[linux-next:master 10231/11867] drivers/gpu/drm/xe/xe_configfs.c:282 lookup_engine_info() error: we previously assumed 'mask' could be null (see line 278)

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Lucas De Marchi <lucas.demarchi@intel.com>
CC: Raag Jadav <raag.jadav@intel.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   ce7f1a983b074f6cf8609068088ca3182c569ee4
commit: e2a9854d806e1cb95861a0f3c7125caaefd7ef03 [10231/11867] drm/xe/configfs: Allow to select by class only
:::::: branch date: 10 hours ago
:::::: commit date: 5 days ago
config: i386-randconfig-141-20250923 (https://download.01.org/0day-ci/archive/20250924/202509241020.mrKHkcLR-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)

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>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202509241020.mrKHkcLR-lkp@intel.com/

smatch warnings:
drivers/gpu/drm/xe/xe_configfs.c:282 lookup_engine_info() error: we previously assumed 'mask' could be null (see line 278)

vim +/mask +282 drivers/gpu/drm/xe/xe_configfs.c

d09bc3edfe5c702 Lucas De Marchi 2025-05-28  256  
e2a9854d806e1cb Lucas De Marchi 2025-09-16  257  /*
e2a9854d806e1cb Lucas De Marchi 2025-09-16  258   * Lookup engine_info. If @mask is not NULL, reduce the mask according to the
e2a9854d806e1cb Lucas De Marchi 2025-09-16  259   * instance in @pattern.
e2a9854d806e1cb Lucas De Marchi 2025-09-16  260   *
e2a9854d806e1cb Lucas De Marchi 2025-09-16  261   * Examples of inputs:
e2a9854d806e1cb Lucas De Marchi 2025-09-16  262   * - lookup_engine_info("rcs0", &mask): return "rcs" entry from @engine_info and
e2a9854d806e1cb Lucas De Marchi 2025-09-16  263   *   mask == BIT_ULL(XE_HW_ENGINE_RCS0)
e2a9854d806e1cb Lucas De Marchi 2025-09-16  264   * - lookup_engine_info("rcs*", &mask): return "rcs" entry from @engine_info and
e2a9854d806e1cb Lucas De Marchi 2025-09-16  265   *   mask == XE_HW_ENGINE_RCS_MASK
e2a9854d806e1cb Lucas De Marchi 2025-09-16  266   * - lookup_engine_info("rcs", NULL): return "rcs" entry from @engine_info
e2a9854d806e1cb Lucas De Marchi 2025-09-16  267   */
e2a9854d806e1cb Lucas De Marchi 2025-09-16  268  static const struct engine_info *lookup_engine_info(const char *pattern, u64 *mask)
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  269  {
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  270  	for (size_t i = 0; i < ARRAY_SIZE(engine_info); i++) {
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  271  		u8 instance;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  272  		u16 bit;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  273  
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  274  		if (!str_has_prefix(pattern, engine_info[i].cls))
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  275  			continue;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  276  
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  277  		pattern += strlen(engine_info[i].cls);
e2a9854d806e1cb Lucas De Marchi 2025-09-16 @278  		if (!mask && !*pattern)
e2a9854d806e1cb Lucas De Marchi 2025-09-16  279  			return &engine_info[i];
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  280  
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  281  		if (!strcmp(pattern, "*")) {
d09bc3edfe5c702 Lucas De Marchi 2025-05-28 @282  			*mask = engine_info[i].mask;
e2a9854d806e1cb Lucas De Marchi 2025-09-16  283  			return &engine_info[i];
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  284  		}
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  285  
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  286  		if (kstrtou8(pattern, 10, &instance))
e2a9854d806e1cb Lucas De Marchi 2025-09-16  287  			return NULL;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  288  
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  289  		bit = __ffs64(engine_info[i].mask) + instance;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  290  		if (bit >= fls64(engine_info[i].mask))
e2a9854d806e1cb Lucas De Marchi 2025-09-16  291  			return NULL;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  292  
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  293  		*mask = BIT_ULL(bit);
e2a9854d806e1cb Lucas De Marchi 2025-09-16  294  		return &engine_info[i];
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  295  	}
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  296  
e2a9854d806e1cb Lucas De Marchi 2025-09-16  297  	return NULL;
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  298  }
d09bc3edfe5c702 Lucas De Marchi 2025-05-28  299  

:::::: The code at line 282 was first introduced by commit
:::::: d09bc3edfe5c702463e2640314b7db2219242446 drm/xe/configfs: Add attribute to disable engines

:::::: TO: Lucas De Marchi <lucas.demarchi@intel.com>
:::::: CC: Lucas De Marchi <lucas.demarchi@intel.com>

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