drm/i915: add a helper to make a copy of i915_params

Abstract the one user in anticipation of more.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c6a94b4da8dc723df025b1f602fe46d76d00d53f.1545920737.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -1834,18 +1834,9 @@ static void capture_gen_state(struct i915_gpu_state *error)
 	error->driver_caps = i915->caps;
 }
 
-static __always_inline void dup_param(const char *type, void *x)
-{
-	if (!__builtin_strcmp(type, "char *"))
-		*(void **)x = kstrdup(*(void **)x, GFP_ATOMIC);
-}
-
 static void capture_params(struct i915_gpu_state *error)
 {
-	error->params = i915_modparams;
+	i915_params_copy(&error->params, &i915_modparams);
-#define DUP(T, x, ...) dup_param(#T, &error->params.x);
-	I915_PARAMS_FOR_EACH(DUP);
-#undef DUP
 }
 
 static unsigned long capture_find_epoch(const struct i915_gpu_state *error)

drivers/gpu/drm/i915/i915_params.c

@@ -203,3 +203,17 @@ void i915_params_dump(const struct i915_params *params, struct drm_printer *p)
 	I915_PARAMS_FOR_EACH(PRINT);
 #undef PRINT
 }
+
+static __always_inline void dup_param(const char *type, void *x)
+{
+	if (!__builtin_strcmp(type, "char *"))
+		*(void **)x = kstrdup(*(void **)x, GFP_ATOMIC);
+}
+
+void i915_params_copy(struct i915_params *dest, const struct i915_params *src)
+{
+	*dest = *src;
+#define DUP(T, x, ...) dup_param(#T, &dest->x);
+	I915_PARAMS_FOR_EACH(DUP);
+#undef DUP
+}

drivers/gpu/drm/i915/i915_params.h

@@ -78,6 +78,7 @@ struct i915_params {
 extern struct i915_params i915_modparams __read_mostly;
 
 void i915_params_dump(const struct i915_params *params, struct drm_printer *p);
+void i915_params_copy(struct i915_params *dest, const struct i915_params *src);
 
 #endif