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QIOChannelSocket: Fix zero-copy flush returning code 1 when nothing sent

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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: 2bc58ffc29 ("QIOChannelSocket: Implement io_writev zero copy flag & io_flush for CONFIG_LINUX")
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220711211112.18951-2-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Leonardo Bras 2022-07-11 18:11:11 -03:00 committed by Dr. David Alan Gilbert
parent 5f87072e95
commit 927f93e099
1 changed files with 7 additions and 1 deletions
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8
io/channel-socket.c
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@ -716,12 +716,18 @@ static int qio_channel_socket_flush(QIOChannel *ioc,
struct cmsghdr *cm; struct cmsghdr *cm;
char control[CMSG_SPACE(sizeof(*serr))]; char control[CMSG_SPACE(sizeof(*serr))];
int received; int received;
int ret = 1; int ret;
if (sioc->zero_copy_queued == sioc->zero_copy_sent) {
return 0;
}
msg.msg_control = control; msg.msg_control = control;
msg.msg_controllen = sizeof(control); msg.msg_controllen = sizeof(control);
memset(control, 0, sizeof(control)); memset(control, 0, sizeof(control));
ret = 1;
while (sioc->zero_copy_sent < sioc->zero_copy_queued) { while (sioc->zero_copy_sent < sioc->zero_copy_queued) {
received = recvmsg(sioc->fd, &msg, MSG_ERRQUEUE); received = recvmsg(sioc->fd, &msg, MSG_ERRQUEUE);
if (received < 0) { if (received < 0) {