[PATCH] USB MSD: Set s->req to NULL after handling a packet

[PATCH] USB MSD: Set s->req to NULL after handling a packet

[Hannes Bredberg]

This fixes compatibility for OSes which enqueue multiple data transfers
on the same endpoint without waiting for the previous one to be ACKed by
the mass storage device.

Signed-off-by: Hannes Bredberg <hannesbredberg@gmail.com>
---
 hw/usb/dev-storage.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index b13fe345c4..43d57afd00 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -182,13 +182,14 @@ static void usb_msd_packet_complete(MSDState *s,
int status)
     USBPacket *p = s->packet;

     /*
-     * Set s->packet to NULL before calling usb_packet_complete
+     * Set s->packet and s->req to NULL before calling usb_packet_complete
      * because another request may be issued before
      * usb_packet_complete returns.
      */
     trace_usb_msd_packet_complete();
     p->status = status;
     s->packet = NULL;
+    s->req = NULL;
     usb_packet_complete(&s->dev, p);
 }

--
2.47.0

Re: [PATCH] USB MSD: Set s->req to NULL after handling a packet

[Peter Maydell]

On Thu, 10 Jul 2025 at 18:54, Hannes Bredberg <hannesbredberg@gmail.com> wrote:
>
> This fixes compatibility for OSes which enqueue multiple data transfers
> on the same endpoint without waiting for the previous one to be ACKed by
> the mass storage device.

Which OSes are these? If there's a specific one that users
might be having problems with and we're fixing a bug for
them, that's worth noting.

thanks
-- PMM