drm: Fix error handling in drm_legacy_addctx

'ctx->handle' is unsigned, it never less than zero.
This patch use int 'tmp_handle' to handle the err condition.

Fixes: 62968144e673 ("drm: convert drm context code to use Linux idr")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181229024907.12852-1-yuehaibing@huawei.com

diff --git a/drivers/gpu/drm/drm_context.c b/drivers/gpu/drm/drm_context.c
index 506663c69b0a1e443a7dccb4a62dae117cc105de..6e8e1a9fcae301a2417316ac4331dcfc060daaf1 100644 (file)
--- a/drivers/gpu/drm/drm_context.c
+++ b/drivers/gpu/drm/drm_context.c
@@ -361,23 +361,26 @@ int drm_legacy_addctx(struct drm_device *dev, void *data,
 {
        struct drm_ctx_list *ctx_entry;
        struct drm_ctx *ctx = data;
+       int tmp_handle;
 
        if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
            !drm_core_check_feature(dev, DRIVER_LEGACY))
                return -EOPNOTSUPP;
 
-       ctx->handle = drm_legacy_ctxbitmap_next(dev);
-       if (ctx->handle == DRM_KERNEL_CONTEXT) {
+       tmp_handle = drm_legacy_ctxbitmap_next(dev);
+       if (tmp_handle == DRM_KERNEL_CONTEXT) {
                /* Skip kernel's context and get a new one. */
-               ctx->handle = drm_legacy_ctxbitmap_next(dev);
+               tmp_handle = drm_legacy_ctxbitmap_next(dev);
        }
-       DRM_DEBUG("%d\n", ctx->handle);
-       if (ctx->handle < 0) {
+       DRM_DEBUG("%d\n", tmp_handle);
+       if (tmp_handle < 0) {
                DRM_DEBUG("Not enough free contexts.\n");
                /* Should this return -EBUSY instead? */
-               return -ENOMEM;
+               return tmp_handle;
        }
 
+       ctx->handle = tmp_handle;
+
        ctx_entry = kmalloc(sizeof(*ctx_entry), GFP_KERNEL);
        if (!ctx_entry) {
                DRM_DEBUG("out of memory\n");