Hi NÃmeth, On 16.12.2010 08:31, NÃmeth MÃrton wrote: > NÃmeth MÃrton wrote: >> I'm working with usbip and I sometimes see a stall when I run >> the "lsusb" command from the userspace. Does it eventually recover? >> I added some debug messages >> and it seems that the kernel_recvmsg() in >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/staging/usbip/usbip_common.c;h=210ef16bab8d271a52e5d36cd1994aad57ad99e1;hb=HEAD >> >> This is the only place I could find where the TCP messages are arriving in >> the usbip code. >> >> What happens if a message does not arrive? Does it stall forever? Yes, it will block until detached or until a TCP timeout or error closes the connection. The TCP timeout can take several minutes. >> yes, how can the kernel_recvmsg() call changed to handle some timeout? > > I found that the userspace manpage of recvmsg(2) ("man recvmsg") contains description > of the "flags" parameter. I suppose the parameters and behaviour of the userspace > recvmsg() is the same as the kernelspace kernel_recvmsg(). I recently faced this problem, too. The solution I arrived at was to set SO_RCVTIMEO and SO_SNDTIMEO socket opts in the tools together with the patch below. The patch works around a lack of heart-beat in the usbip protocol which would otherwise make idle connections time out. (It wont apply cleanly but hopefully conveys the idea.). Extending the protocol for a heart-beat message doesn't seem to be possible without breaking the compatibility at the same time. I was planning to submit it on the weekend along with the tool changes to set the timeouts. Max --- From: Max Vozeler <max@xxxxxxxxxxx> Date: Mon, 13 Dec 2010 00:39:14 +0100 Subject: [PATCH 1/3] vhci: allow SO_RCVTIMEO on the socket In case of unanswered replies, a receive timeout is considered a connection error and the device will be shut down and removed. This is a workaround for the lack of heart-beat messages in the USBIP protocol. It allows userspace to set a maximum latency for the connection. --- vhci_rx.c | 21 ++++++++++++++++++++- 1 files changed, 20 insertions(+), 1 deletions(-) diff --git a/vhci_rx.c b/vhci_rx.c index bc16dc4..9a1fe80 100644 --- a/vhci_rx.c +++ b/vhci_rx.c @@ -197,6 +197,19 @@ 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) { @@ -216,8 +229,14 @@ static void vhci_rx_pdu(struct usbip_device *ud) usbip_uinfo("connection reset by peer\n"); else if (ret == -ETIMEDOUT) usbip_uinfo("connection timed out\n"); - else if (ret != -ERESTARTSYS) + else if (ret == -EAGAIN) { + /* 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; } -- 1.7.2.3 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
