On Tue, Oct 29, 2024 at 03:55:58PM -0300, Jason Gunthorpe wrote:
On Tue, Oct 29, 2024 at 09:18:05AM -0700, Nicolin Chen wrote:
I think we'd need the same change in iommufd_object_abort() too.
Makes sense
I found xa_cmpxchg() does xas_result to its returning value, which turns XA_ZERO_ENTRY into NULL failing our intended verifications.
So, I replaced that further with xas_store: ----------------------------------------------------------------- @@ -41,20 +41,26 @@ static struct miscdevice vfio_misc_dev; void iommufd_object_finalize(struct iommufd_ctx *ictx, struct iommufd_object *obj) { + XA_STATE(xas, &ictx->objects, obj->id); void *old;
- old = xa_store(&ictx->objects, obj->id, obj, GFP_KERNEL); - /* obj->id was returned from xa_alloc() so the xa_store() cannot fail */ - WARN_ON(old); + xa_lock(&ictx->objects); + old = xas_store(&xas, obj); + xa_unlock(&ictx->objects); + /* obj->id was returned from xa_alloc() so the xas_store() cannot fail */ + WARN_ON(old != XA_ZERO_ENTRY); }
/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */ void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj) { + XA_STATE(xas, &ictx->objects, obj->id); void *old;
- old = xa_erase(&ictx->objects, obj->id); - WARN_ON(old); + xa_lock(&ictx->objects); + old = xas_store(&xas, NULL); + xa_unlock(&ictx->objects); + WARN_ON(old != XA_ZERO_ENTRY); kfree(obj); } -----------------------------------------------------------------
Thanks Nicolin