media: v4l2-subdev: Fix alloc failure check in v4l2_subdev_call_state_try()

v4l2_subdev_call_state_try() macro allocates a subdev state with
__v4l2_subdev_state_alloc(), but does not check the returned value. If
__v4l2_subdev_state_alloc fails, it returns an ERR_PTR, and that would
cause v4l2_subdev_call_state_try() to crash.

Add proper error handling to v4l2_subdev_call_state_try().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Fixes: 982c048 ("media: subdev: Add v4l2_subdev_call_state_try() macro")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/aJTNtpDUbTz7eyJc%40stanley.mountain/
Cc: stable@vger.kernel.org
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

Author: tomba

include/media/v4l2-subdev.h

@@ -1939,19 +1939,23 @@ extern const struct v4l2_subdev_ops v4l2_subdev_call_wrappers;
  *
  * Note: only legacy non-MC drivers may need this macro.
  */
-#define v4l2_subdev_call_state_try(sd, o, f, args...)                 \
-	({                                                            \
-		int __result;                                         \
-		static struct lock_class_key __key;                   \
-		const char *name = KBUILD_BASENAME                    \
-			":" __stringify(__LINE__) ":state->lock";     \
-		struct v4l2_subdev_state *state =                     \
-			__v4l2_subdev_state_alloc(sd, name, &__key);  \
-		v4l2_subdev_lock_state(state);                        \
-		__result = v4l2_subdev_call(sd, o, f, state, ##args); \
-		v4l2_subdev_unlock_state(state);                      \
-		__v4l2_subdev_state_free(state);                      \
-		__result;                                             \
+#define v4l2_subdev_call_state_try(sd, o, f, args...)                         \
+	({                                                                    \
+		int __result;                                                 \
+		static struct lock_class_key __key;                           \
+		const char *name = KBUILD_BASENAME                            \
+			":" __stringify(__LINE__) ":state->lock";             \
+		struct v4l2_subdev_state *state =                             \
+			__v4l2_subdev_state_alloc(sd, name, &__key);          \
+		if (IS_ERR(state)) {                                          \
+			__result = PTR_ERR(state);                            \
+		} else {                                                      \
+			v4l2_subdev_lock_state(state);                        \
+			__result = v4l2_subdev_call(sd, o, f, state, ##args); \
+			v4l2_subdev_unlock_state(state);                      \
+			__v4l2_subdev_state_free(state);                      \
+		}                                                             \
+		__result;                                                     \
 	})
 
 /**