drm_legacy_ctxbitmap_next() returns idr_alloc() which can return
-ENOMEM, -EINVAL or -ENOSPC none of which are -1. since drm_context_t
is an unsigned int an intermediate variable is used to handle the
error cases, and then cast to drm_context_t after ensuring that the
value is >= 0. The explicit cast is to mark the type conversion as
intentional.
Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Reported-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
Fixes: d530b5f1ca0b ("drm: re-enable error handling")
Fixes: 62968144e673 ("drm: convert drm context code to use Linux idr")
---
V3: bug in patch - omission to remove old code properly - V3 fixes the
original problem as proposed in V2 and drops the excess line.
reported by Sean Paul <seanpaul@xxxxxxxxxxxx> - thanks!
V2: The proposed fix in d530b5f1ca0b ("drm: re-enable error handling")
actually was ineffective as the negative return value check was
against a unsigned int and thus always false as reported by
kbuild test robot <lkp@xxxxxxxxx>. The below patch removes that
warning and fixes the original problem of missed error handling.
drm_context_t is actually just used in a few placed so the type could be
changed but it is also exported via tools/include/uapi/drm/drm.h so
changing the typedef of drm_context_t could break applications and thus
this is not an option.
Patch was compile tested with: x86_64_defconfig
Patch is against 4.18-rc5 (localversion-next is next-20180718)
drivers/gpu/drm/drm_context.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_context.c b/drivers/gpu/drm/drm_context.c
index f973d28..ad268c8 100644
--- a/drivers/gpu/drm/drm_context.c
+++ b/drivers/gpu/drm/drm_context.c
@@ -361,22 +361,25 @@ int drm_legacy_addctx(struct drm_device *dev, void *data,
{
struct drm_ctx_list *ctx_entry;
struct drm_ctx *ctx = data;
+ int ret;
if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
!drm_core_check_feature(dev, DRIVER_LEGACY))
return -EINVAL;
- ctx->handle = drm_legacy_ctxbitmap_next(dev);
- if (ctx->handle == DRM_KERNEL_CONTEXT) {
+ ret = drm_legacy_ctxbitmap_next(dev);
+ if (ret == DRM_KERNEL_CONTEXT) {
/* Skip kernel's context and get a new one. */
- ctx->handle = drm_legacy_ctxbitmap_next(dev);
+ ret = drm_legacy_ctxbitmap_next(dev);
}
- DRM_DEBUG("%d\n", ctx->handle);
- if (ctx->handle < 0) {
+ DRM_DEBUG("ctxbitmap is error code %d\n", ret);
+ if (ret < 0) {
DRM_DEBUG("Not enough free contexts.\n");
/* Should this return -EBUSY instead? */
return -ENOMEM;
}
+ /* valid context is >= 0 */
+ ctx->handle = (drm_context_t)ret;
ctx_entry = kmalloc(sizeof(*ctx_entry), GFP_KERNEL);
if (!ctx_entry) {
--
2.1.4
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel
