Re: [PATCH for-6.0 v2 4/8] hw/block/nvme: fix controller namespaces array indexing

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 4/5/21 7:54 PM, Klaus Jensen wrote:
> From: Klaus Jensen <k.jensen@samsung.com>
> 
> The controller namespaces array being 0-indexed requires 'nsid - 1'
> everywhere. Something that is easy to miss. Align the controller
> namespaces array with the subsystem namespaces array such that both are
> 1-indexed.

TBH I don't understand the justification. Assuming you hit a
bug and try to protect yourself, maybe now you should also
check for

  assert(n->namespaces[0] == NULL);

somewhere. In nvme_ns() maybe?

> 
> Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> Reviewed-by: Gollu Appalanaidu <anaidu.gollu@samsung.com>
> ---
>  hw/block/nvme.h | 8 ++++----
>  hw/block/nvme.c | 2 +-
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/block/nvme.h b/hw/block/nvme.h
> index 9edc86d79e98..c610ab30dc5c 100644
> --- a/hw/block/nvme.h
> +++ b/hw/block/nvme.h
> @@ -217,7 +217,7 @@ typedef struct NvmeCtrl {
>       * Attached namespaces to this controller.  If subsys is not given, all
>       * namespaces in this list will always be attached.
>       */
> -    NvmeNamespace   *namespaces[NVME_MAX_NAMESPACES];
> +    NvmeNamespace   *namespaces[NVME_MAX_NAMESPACES + 1];
>      NvmeSQueue      **sq;
>      NvmeCQueue      **cq;
>      NvmeSQueue      admin_sq;
> @@ -232,7 +232,7 @@ static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid)
>          return NULL;
>      }
>  
> -    return n->namespaces[nsid - 1];
> +    return n->namespaces[nsid];
>  }
>  
>  static inline bool nvme_ns_is_attached(NvmeCtrl *n, NvmeNamespace *ns)
> @@ -253,7 +253,7 @@ static inline void nvme_ns_attach(NvmeCtrl *n, NvmeNamespace *ns)
>      uint32_t nsid = nvme_nsid(ns);
>      assert(nsid && nsid <= NVME_MAX_NAMESPACES);
>  
> -    n->namespaces[nsid - 1] = ns;
> +    n->namespaces[nsid] = ns;
>  }
>  
>  static inline void nvme_ns_detach(NvmeCtrl *n, NvmeNamespace *ns)
> @@ -261,7 +261,7 @@ static inline void nvme_ns_detach(NvmeCtrl *n, NvmeNamespace *ns)
>      uint32_t nsid = nvme_nsid(ns);
>      assert(nsid && nsid <= NVME_MAX_NAMESPACES);
>  
> -    n->namespaces[nsid - 1] = NULL;
> +    n->namespaces[nsid] = NULL;
>  }
>  
>  static inline NvmeCQueue *nvme_cq(NvmeRequest *req)
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index c54ec3c9523c..6d31d5b17a0b 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -5915,7 +5915,7 @@ int nvme_register_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
>              return -1;
>          }
>      } else {
> -        if (n->namespaces[nsid - 1]) {
> +        if (n->namespaces[nsid]) {
>              error_setg(errp, "namespace id '%d' is already in use", nsid);
>              return -1;
>          }
>