matt mooney wrote: > On 22:25 Tue 24 May , NÃmeth MÃrton wrote: >> Greg KH wrote: >>> I think the code is the "real" documentation. > > I concur! > >> If it is, then I need to read it in the right way, through it is not an easy task. >> I tried to find the points in the USBIP kernel code where opening, sending, >> receiving and closing of the TCP connection takes place. I took all function names >> from linux/net.h and I found the following places so far: >> >> $ grep -n -E >> 'sock_wake_async|sock_register|sock_unregister|sock_create|sock_create_kern|sock_create_lite|sock_release|sock_sendmsg|sock_recvmsg|sock_map_fd|sockfd_lookup|sockfd_put|net_ratelimit|kernel_sendmsg|kernel_recvmsg|kernel_bind|kernel_listen|kernel_accept|kernel_connect|kernel_getsockname|kernel_getpeername|kernel_getsockopt|kernel_setsockopt|kernel_sendpage|kernel_sock_ioctl|kernel_sock_shutdown|SHUT_' >> linux-2.6/drivers/staging/usbip/* >> >> linux-2.6/drivers/staging/usbip/stub_dev.c:201: kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR); >> linux-2.6/drivers/staging/usbip/stub_dev.c:216: sock_release(ud->tcp_socket); >> linux-2.6/drivers/staging/usbip/stub_tx.c:263: ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, >> linux-2.6/drivers/staging/usbip/stub_tx.c:338: ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, iov, >> linux-2.6/drivers/staging/usbip/usbip_common.c:382: result = kernel_sendmsg(sock, &msg, &iov, 1, size); >> linux-2.6/drivers/staging/usbip/usbip_common.c:384: result = kernel_recvmsg(sock, &msg, &iov, 1, size, >> linux-2.6/drivers/staging/usbip/vhci_hcd.c:845: kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR); >> linux-2.6/drivers/staging/usbip/vhci_hcd.c:858: sock_release(vdev->ud.tcp_socket); >> linux-2.6/drivers/staging/usbip/vhci_tx.c:119: ret = kernel_sendmsg(vdev->ud.tcp_socket, &msg, iov, 3, txsize); >> linux-2.6/drivers/staging/usbip/vhci_tx.c:189: ret = kernel_sendmsg(vdev->ud.tcp_socket, &msg, iov, 1, txsize); >> >> I guess this is not all, there is also a protocol defined to the user-space world. > > Very true, and part of what is taking place is a unification of the userspace > and kernel protocols. Then there will be some degree of documentation. Mainly in > the form of packet diagrams to show on-wire communication. Could you please give some hints witch function names to look for and where to start "reading" the source code to see how the userspace protocol looks like? > On Tue, May 24, 2011 at 10:25:18PM +0200, NÃmeth MÃrton wrote: >> The current protocol implementation is based on top of TCP. In the message >> at http://marc.info/?l=linux-kernel&m=122001883519653&w=2 the SCTP is mentioned. >> Have anybody worked on finding out what benefits the SCTP could give to USBIP >> and what would be the drawbacks? Greg KH wrote: > It might not work well on Windows, which the current code does today. > > I think that the TCP vs. SCTP is the least of the protocol issues at the > moment, there are lots of other things to work on :) matt mooney wrote: > I think sctp would be interesting, but as greg said, and I tend to agree, this > is the least of usbip's problems. > > (Maybe eliminating the need to interact w/ windows would be a good project ;) > jk! OK, I see your point. I tried to check the "source code" for a TODO list, but I think I failed at that point because I just found: | $ cat linux-2.6/drivers/staging/usbip/README | TODO: | - more discussion about the protocol | - testing | - review of the userspace interface | | Please send patches for this code to Greg Kroah-Hartman <greg@xxxxxxxxx> These are quite hard tasks to solve. More discussion about the protocol? I think the first problem is that it is difficult (at least for me) to see clearly the protocol because of lack of documentation. Testing: when you test something you compare the running code against something. If you compare the running code against the source code then you will not test the USBIP implementation/protocol, but the compiler itself, whether the compiler generated the same code which is available in source format. Review of the userspace interface: first I will need to understand how it looks like befor I can do anything on this point. Do you have a bit detailed TODO list somewhere written down or in your heads so beginners can also help? E.g. running "scripts/checkpatch.pl -f" and solving the errors/warnings helps at this point? Or compiling with "make W=1 C=1 ..." and solving those warnings helps? Regards, MÃrton NÃmeth -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
