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staging: usbip: vhci: handle EAGAIN from SO_RCVTIMEO

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If there is a receive timeout without any active
requests, we can tell the connection was idle and
ignore the timeout.

If there are active requests for which we expect
to receive a reply we close the connection.

This makes it possible to set an upper bound on
the time a usbip device may be unresponsive.

This is a workaround for the lack of heart-beat
messages in the USBIP protocol.

Extending the protocol would break compatibility
with all previous stub versions, so this seems like
the lesser evil.

Signed-off-by: Max Vozeler <max@vozeler.com>
Tested-by: Mark Wehby <MWehby@luxotticaRetail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Max Vozeler 2011-01-12 15:02:04 +02:00 committed by Greg Kroah-Hartman
parent 7e249c8b07
commit bd65f6233f
1 changed files with 20 additions and 1 deletions
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21
drivers/staging/usbip/vhci_rx.c
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@ -193,6 +193,19 @@ static void vhci_recv_ret_unlink(struct vhci_device *vdev,
return;
}
static int vhci_priv_tx_empty(struct vhci_device *vdev)
{
int empty = 0;
spin_lock(&vdev->priv_lock);
empty = list_empty(&vdev->priv_rx);
spin_unlock(&vdev->priv_lock);
return empty;
}
/* recv a pdu */
static void vhci_rx_pdu(struct usbip_device *ud)
{
@ -210,8 +223,14 @@ static void vhci_rx_pdu(struct usbip_device *ud)
if (ret < 0) {
if (ret == -ECONNRESET)
usbip_uinfo("connection reset by peer\n");
else if (ret != -ERESTARTSYS)
else if (ret == -EAGAIN) {
/* ignore if connection was idle */
if (vhci_priv_tx_empty(vdev))
return;
usbip_uinfo("connection timed out with pending urbs\n");
} else if (ret != -ERESTARTSYS)
usbip_uinfo("xmit failed %d\n", ret);
usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
return;
}