drm/i915/gem: Return an error ptr from context_lookup

We're about to start doing lazy context creation which means contexts
get created in i915_gem_context_lookup and we may start having more
errors than -ENOENT.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210708154835.528166-23-jason@jlekstrand.net

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

@@ -2636,8 +2636,8 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 	int ret = 0;
 
 	ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
-	if (!ctx)
-		return -ENOENT;
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
 
 	switch (args->param) {
 	case I915_CONTEXT_PARAM_GTT_SIZE:
@@ -2705,8 +2705,8 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
 	int ret;
 
 	ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
-	if (!ctx)
-		return -ENOENT;
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
 
 	ret = ctx_setparam(file_priv, ctx, args);
 
@@ -2725,8 +2725,8 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev,
 		return -EINVAL;
 
 	ctx = i915_gem_context_lookup(file->driver_priv, args->ctx_id);
-	if (!ctx)
-		return -ENOENT;
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
 
 	/*
 	 * We opt for unserialised reads here. This may result in tearing

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -739,8 +739,8 @@ static int eb_select_context(struct i915_execbuffer *eb)
 	struct i915_gem_context *ctx;
 
 	ctx = i915_gem_context_lookup(eb->file->driver_priv, eb->args->rsvd1);
-	if (unlikely(!ctx))
-		return -ENOENT;
+	if (unlikely(IS_ERR(ctx)))
+		return PTR_ERR(ctx);
 
 	eb->gem_context = ctx;
 	if (rcu_access_pointer(ctx->vm))

drivers/gpu/drm/i915/i915_drv.h

@@ -1858,7 +1858,7 @@ i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32 id)
 		ctx = NULL;
 	rcu_read_unlock();
 
-	return ctx;
+	return ctx ? ctx : ERR_PTR(-ENOENT);
 }
 
 static inline struct i915_address_space *

drivers/gpu/drm/i915/i915_perf.c

@@ -3414,10 +3414,10 @@ i915_perf_open_ioctl_locked(struct i915_perf *perf,
 		struct drm_i915_file_private *file_priv = file->driver_priv;
 
 		specific_ctx = i915_gem_context_lookup(file_priv, ctx_handle);
-		if (!specific_ctx) {
+		if (IS_ERR(specific_ctx)) {
 			DRM_DEBUG("Failed to look up context with ID %u for opening perf stream\n",
 				  ctx_handle);
-			ret = -ENOENT;
+			ret = PTR_ERR(specific_ctx);
 			goto err;
 		}
 	}