Re: [Qemu-devel] [PATCH 1/3] Revert "usb-storage: Drop useless null test in usb_msd_handle_data()"

[Markus Armbruster]

Gerd Hoffmann <address@hidden> writes:

> This reverts commit a1cbfd554e11bb8af38c2f3e1f1574bf4c563cd2.
>
> Test isn't useless.  scsi_req_enqueue() may finish the request (will
> actually happen for requests which don't trigger any I/O such as
> INQUIRY), then call usb_msd_command_complete() which in turn will
> set s->req to NULL after unref'ing it.
>
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  hw/usb/dev-storage.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
> index b839798..1b87352 100644
> --- a/hw/usb/dev-storage.c
> +++ b/hw/usb/dev-storage.c
> @@ -427,7 +427,7 @@ static void usb_msd_handle_data(USBDevice *dev, USBPacket 
> *p)
>              scsi_req_print(s->req);
>  #endif
>              scsi_req_enqueue(s->req);
> -            if (s->req->cmd.xfer != SCSI_XFER_NONE) {
> +            if (s->req && s->req->cmd.xfer != SCSI_XFER_NONE) {
>                  scsi_req_continue(s->req);
>              }
>              break;

No objection to the revert, and sorry for screwing this up.

However, we generally use scsi_req_enqueue() like this:

    n = scsi_req_enqueue(req);
    if (n) {
        [...]
        scsi_req_continue(req);
    }

Any particular reason to do it differently here?