From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34287) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VbB1l-0007OF-H2 for qemu-devel@nongnu.org; Tue, 29 Oct 2013 11:16:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VbB1f-0001vs-UF for qemu-devel@nongnu.org; Tue, 29 Oct 2013 11:16:17 -0400 Received: from mail-bk0-x22f.google.com ([2a00:1450:4008:c01::22f]:38402) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VbB1f-0001vk-H3 for qemu-devel@nongnu.org; Tue, 29 Oct 2013 11:16:11 -0400 Received: by mail-bk0-f47.google.com with SMTP id mx12so2447298bkb.20 for ; Tue, 29 Oct 2013 08:16:10 -0700 (PDT) Date: Tue, 29 Oct 2013 15:55:42 +0100 From: Stefan Hajnoczi Message-ID: <20131029145542.GA1929@stefanha-thinkpad.redhat.com> References: <1366284715-10107-1-git-send-email-s.fedorov@samsung.com> <20130422114711.GA21317@stefanha-thinkpad.redhat.com> <51752C68.6030408@samsung.com> <20130422145749.GA28049@stefanha-thinkpad.redhat.com> <517556D9.2080809@samsung.com> <20130423065841.GA6447@stefanha-thinkpad.redhat.com> <51763B36.1000701@samsung.com> <20130423120021.GC2431@stefanha-thinkpad.redhat.com> <526513AE.2050605@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <526513AE.2050605@samsung.com> Subject: Re: [Qemu-devel] [PATCH] net/hub: remove can_receive handler List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fedorov Sergey Cc: Stefan Hajnoczi , a.basov@samsung.com, qemu-devel@nongnu.org, Anthony Liguori On Mon, Oct 21, 2013 at 03:44:46PM +0400, Fedorov Sergey wrote: > After our discussion about this patch I decided to keep my patch in > our branch until rebase onto a new release. Recently I have rebased > our branch onto v1.5.3 and reverted my patch. Then I face an issue > when using user-mode networking with USB network device for mounting > root file system through NFS. Fragmented UDP packets from host to > guest does not handled properly. Seems that some fragments is lost > or somehow stalled. See guest tcpdump log below. > > 03:16:52.259690 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], > proto UDP (17), length 164) > 10.0.2.15.3369105030 > 10.0.2.2.nfs: 136 readdirplus fh Unknown/0100070004001200000000002873593C9B3C43388E23748B0BAD870C00000000 > 512 bytes @ 0 max 4096 verf 0000000000000000 > 03:16:52.262323 IP (tos 0x0, ttl 64, id 16, offset 0, flags [+], > proto UDP (17), length 1500) > 10.0.2.2.nfs > 10.0.2.15.3369105030: reply ok 1472 readdirplus > POST: DIR 40777 ids 0/0 sz 4096 verf 0000000000000000 > 03:16:52.264592 IP (tos 0x0, ttl 64, id 16, offset 1480, flags [+], > proto UDP (17), length 1500) > 10.0.2.2 > 10.0.2.15: udp > 03:16:54.462961 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], > proto UDP (17), length 164) > 10.0.2.15.3369105030 > 10.0.2.2.nfs: 136 readdirplus fh Unknown/0100070004001200000000002873593C9B3C43388E23748B0BAD870C00000000 > 512 bytes @ 0 max 4096 verf 0000000000000000 > 03:16:54.466300 IP (tos 0x0, ttl 64, id 17, offset 0, flags [+], > proto UDP (17), length 1500) > 10.0.2.2.nfs > 10.0.2.15.3369105030: reply ok 1472 readdirplus > POST: DIR 40777 ids 0/0 sz 4096 verf 0000000000000000 > 03:16:54.467084 IP (tos 0x0, ttl 64, id 17, offset 1480, flags [+], > proto UDP (17), length 1500) > 10.0.2.2 > 10.0.2.15: udp > ... > > I didn't investigate the cause of the problem in detail. I just reverted > > commit 199ee608f0d08510b5c6c37f31a7fbff211d63c4 > Author: Luigi Rizzo > Date: Tue Feb 5 17:53:31 2013 +0100 > > net: fix qemu_flush_queued_packets() in presence of a hub > > And then applied my patch. After that everything works fine for me. > See guest tcpdump log below. > > 04:45:15.897245 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], > proto UDP (17), length 164) > 10.0.2.15.3642011847 > 10.0.2.2.nfs: 136 readdirplus fh Unknown/0100070004001200000000002873593C9B3C43388E23748B0BAD870C00000000 > 512 bytes @ 0 max 4096 verf 0000000000000000 > 04:45:15.899686 IP (tos 0x0, ttl 64, id 15, offset 0, flags [+], > proto UDP (17), length 1500) > 10.0.2.2.nfs > 10.0.2.15.3642011847: reply ok 1472 readdirplus > POST: DIR 40777 ids 0/0 sz 4096 verf 0000000000000000 > 04:45:15.906253 IP (tos 0x0, ttl 64, id 15, offset 1480, flags [+], > proto UDP (17), length 1500) > 10.0.2.2 > 10.0.2.15: udp > 04:45:15.906687 IP (tos 0x0, ttl 64, id 15, offset 2960, flags > [none], proto UDP (17), length 240) > 10.0.2.2 > 10.0.2.15: udp > > So there must be something wrong with already applied patch. What > could you suggest? The next step is to investigate the cause. Perhaps hw/usb/dev-network.c:usb_net_handle_datain() is not calling qemu_flush_queued_packets() every time in_buf[] is read completely. This if statement looks strange to me: if (s->in_ptr >= s->in_len && (is_rndis(s) || (s->in_len & (64 - 1)) || !len)) { /* no short packet necessary */ usb_net_reset_in_buf(s); } Try placing printfs to find out whether qemu_flush_queued_packets() is getting called when you see packet loss. Stefan