drm/xe/configfs: Fix engine class parsing

If mask is NULL, only the engine class should be accepted, so the
pattern string should be completely parsed. This should fix passing e.g.
rcs0 to ctx_restore_post_bb when it's only expecting the engine class.

Reported-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Closes: https://lore.kernel.org/r/20250922155544.67712-1-jonathan.cavitt@intel.com
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/aNJKnrCQmL9xS9Gv@stanley.mountain
Fixes: e2a9854d806e ("drm/xe/configfs: Allow to select by class only")
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Raag Jadav <raag.jadav@intel.com>
Link: https://lore.kernel.org/r/20250924152709.659483-3-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
(cherry picked from commit dd797967160b79cc0ca2d2eb05fc55436b66dce0)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
index 8a9b950e7a6d1c6d7e51c4084a562cffee6702fb..beade13efbae7e8ad7a4d752d1c0b624f413d3eb 100644 (file)
--- a/drivers/gpu/drm/xe/xe_configfs.c
+++ b/drivers/gpu/drm/xe/xe_configfs.c
@@ -324,8 +324,8 @@ static const struct engine_info *lookup_engine_info(const char *pattern, u64 *ma
                        continue;
 
                pattern += strlen(engine_info[i].cls);
-               if (!mask && !*pattern)
-                       return &engine_info[i];
+               if (!mask)
+                       return *pattern ? NULL : &engine_info[i];
 
                if (!strcmp(pattern, "*")) {
                        *mask = engine_info[i].mask;