From 905cc8032fc63619efb3f0a8c9754b7190bcc43a Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Mon, 11 Jul 2022 18:11:11 -0300 Subject: [PATCH 3/9] QIOChannelSocket: Fix zero-copy flush returning code 1 when nothing sent MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Leonardo Brás RH-MergeRequest: 201: Zero-copy-send fixes + improvements RH-Commit: [3/8] 1ad707702fa26cd4d0fa1870c21f5f26ae93ff97 RH-Bugzilla: 2110203 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Peter Xu RH-Acked-by: Miroslav Rezanina If flush is called when no buffer was sent with MSG_ZEROCOPY, it currently returns 1. This return code should be used only when Linux fails to use MSG_ZEROCOPY on a lot of sendmsg(). Fix this by returning early from flush if no sendmsg(...,MSG_ZEROCOPY) was attempted. Fixes: 2bc58ffc2926 ("QIOChannelSocket: Implement io_writev zero copy flag & io_flush for CONFIG_LINUX") Signed-off-by: Leonardo Bras Reviewed-by: Daniel P. Berrangé Acked-by: Daniel P. Berrangé Reviewed-by: Juan Quintela Reviewed-by: Peter Xu Message-Id: <20220711211112.18951-2-leobras@redhat.com> Signed-off-by: Dr. David Alan Gilbert (cherry picked from commit 927f93e099c4f9184e60a1bc61624ac2d04d0223) Signed-off-by: Leonardo Bras --- io/channel-socket.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/io/channel-socket.c b/io/channel-socket.c index df858da924..cf0d67c51b 100644 --- a/io/channel-socket.c +++ b/io/channel-socket.c @@ -717,12 +717,18 @@ static int qio_channel_socket_flush(QIOChannel *ioc, struct cmsghdr *cm; char control[CMSG_SPACE(sizeof(*serr))]; int received; - int ret = 1; + int ret; + + if (sioc->zero_copy_queued == sioc->zero_copy_sent) { + return 0; + } msg.msg_control = control; msg.msg_controllen = sizeof(control); memset(control, 0, sizeof(control)); + ret = 1; + while (sioc->zero_copy_sent < sioc->zero_copy_queued) { received = recvmsg(sioc->fd, &msg, MSG_ERRQUEUE); if (received < 0) { -- 2.31.1