drm/i915/gem: Add a separate validate_priority helper

With the proto-context stuff added later in this series, we end up
having to duplicate set_priority.  This lets us avoid duplicating the
validation logic.
Signed-off-by: NJason Ekstrand <jason@jlekstrand.net>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210708154835.528166-15-jason@jlekstrand.net

drivers/gpu/drm/i915/gem/i915_gem_context.c

@@ -169,6 +169,28 @@ lookup_user_engine(struct i915_gem_context *ctx,
 	return i915_gem_context_get_engine(ctx, idx);
 }
 
+static int validate_priority(struct drm_i915_private *i915,
+			     const struct drm_i915_gem_context_param *args)
+{
+	s64 priority = args->value;
+
+	if (args->size)
+		return -EINVAL;
+
+	if (!(i915->caps.scheduler & I915_SCHEDULER_CAP_PRIORITY))
+		return -ENODEV;
+
+	if (priority > I915_CONTEXT_MAX_USER_PRIORITY ||
+	    priority < I915_CONTEXT_MIN_USER_PRIORITY)
+		return -EINVAL;
+
+	if (priority > I915_CONTEXT_DEFAULT_PRIORITY &&
+	    !capable(CAP_SYS_NICE))
+		return -EPERM;
+
+	return 0;
+}
+
 static struct i915_address_space *
 context_get_vm_rcu(struct i915_gem_context *ctx)
 {
@@ -1744,23 +1766,13 @@ static void __apply_priority(struct intel_context *ce, void *arg)
 static int set_priority(struct i915_gem_context *ctx,
 			const struct drm_i915_gem_context_param *args)
 {
-	s64 priority = args->value;
-
-	if (args->size)
-		return -EINVAL;
-
-	if (!(ctx->i915->caps.scheduler & I915_SCHEDULER_CAP_PRIORITY))
-		return -ENODEV;
-
-	if (priority > I915_CONTEXT_MAX_USER_PRIORITY ||
-	    priority < I915_CONTEXT_MIN_USER_PRIORITY)
-		return -EINVAL;
+	int err;
 
-	if (priority > I915_CONTEXT_DEFAULT_PRIORITY &&
-	    !capable(CAP_SYS_NICE))
-		return -EPERM;
+	err = validate_priority(ctx->i915, args);
+	if (err)
+		return err;
 
-	ctx->sched.priority = priority;
+	ctx->sched.priority = args->value;
 	context_apply_all(ctx, __apply_priority, ctx);
 
 	return 0;