[Qemu-devel] [PULL 11/11] usb-redir: allocate buffers before waking up the host adapter

[Gerd Hoffmann <kraxel@redhat.com>]

From: Hans de Goede <hdegoede@redhat.com>

Needed to make sure usb redirection is prepared to actually handle the
callback from the usb host adapter.  Without this interrupt endpoints
don't work on xhci.

Note: On ehci the usb_wakeup() call only schedules a BH for the actual
work, which hides this bug because the allocation happens before ehci
calls back even without this patch.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Message-id: 1476096313-7730-1-git-send-email-kraxel@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/redirect.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
index 444672a..d4ca026 100644
--- a/hw/usb/redirect.c
+++ b/hw/usb/redirect.c
@@ -2036,18 +2036,22 @@ static void usbredir_interrupt_packet(void *priv, uint64_t id,
     }
 
     if (ep & USB_DIR_IN) {
+        bool q_was_empty;
+
         if (dev->endpoint[EP2I(ep)].interrupt_started == 0) {
             DPRINTF("received int packet while not started ep %02X\n", ep);
             free(data);
             return;
         }
 
-        if (QTAILQ_EMPTY(&dev->endpoint[EP2I(ep)].bufpq)) {
-            usb_wakeup(usb_ep_get(&dev->dev, USB_TOKEN_IN, ep & 0x0f), 0);
-        }
+        q_was_empty = QTAILQ_EMPTY(&dev->endpoint[EP2I(ep)].bufpq);
 
         /* bufp_alloc also adds the packet to the ep queue */
         bufp_alloc(dev, data, data_len, interrupt_packet->status, ep, data);
+
+        if (q_was_empty) {
+            usb_wakeup(usb_ep_get(&dev->dev, USB_TOKEN_IN, ep & 0x0f), 0);
+        }
     } else {
         /*
          * We report output interrupt packets as completed directly upon
-- 
1.8.3.1