From: "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>
To: qemu-devel@nongnu.org, mst@redhat.com, marcandre.lureau@redhat.com
Subject: [Qemu-devel] [PATCH] libvhost-user: Send messages with no data
Date: Fri, 4 May 2018 10:53:46 +0100 [thread overview]
Message-ID: <20180504095346.14159-1-dgilbert@redhat.com> (raw)
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
The response to a VHOST_USER_POSTCOPY_ADVISE contains a fd but doesn't
actually contain any data. FIx vu_message_write so that it doesn't
do a 0-byte write() call, since this was ending up with rc=0
that was confusing the error handling code.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
contrib/libvhost-user/libvhost-user.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index beeed0c43f..54e643d871 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -323,13 +323,15 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
rc = sendmsg(conn_fd, &msg, 0);
} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
- do {
- if (vmsg->data) {
- rc = write(conn_fd, vmsg->data, vmsg->size);
- } else {
- rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
- }
- } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+ if (vmsg->size) {
+ do {
+ if (vmsg->data) {
+ rc = write(conn_fd, vmsg->data, vmsg->size);
+ } else {
+ rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
+ }
+ } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+ }
if (rc <= 0) {
vu_panic(dev, "Error while writing: %s", strerror(errno));
--
2.17.0
next reply other threads:[~2018-05-04 9:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 9:53 Dr. David Alan Gilbert (git) [this message]
2018-05-04 9:56 ` [Qemu-devel] [PATCH] libvhost-user: Send messages with no data Marc-André Lureau
2018-05-04 13:09 ` Eric Blake
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