From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49772) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yi4Gd-000685-UC for qemu-devel@nongnu.org; Tue, 14 Apr 2015 13:04:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yi4Gb-0002Im-5Z for qemu-devel@nongnu.org; Tue, 14 Apr 2015 13:04:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48288) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yi4Ga-0002IU-UP for qemu-devel@nongnu.org; Tue, 14 Apr 2015 13:04:53 -0400 From: "Dr. David Alan Gilbert (git)" Date: Tue, 14 Apr 2015 18:03:38 +0100 Message-Id: <1429031053-4454-13-git-send-email-dgilbert@redhat.com> In-Reply-To: <1429031053-4454-1-git-send-email-dgilbert@redhat.com> References: <1429031053-4454-1-git-send-email-dgilbert@redhat.com> Subject: [Qemu-devel] [PATCH v6 12/47] Return path: socket_writev_buffer: Block even on non-blocking fd's List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, david@gibson.dropbear.id.au, yayanghy@cn.fujitsu.com From: "Dr. David Alan Gilbert" The destination sets the fd to non-blocking on incoming migrations; this also affects the return path from the destination, and thus we need to make sure we can safely write to the return path. Signed-off-by: Dr. David Alan Gilbert --- migration/qemu-file-unix.c | 41 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 36 insertions(+), 5 deletions(-) diff --git a/migration/qemu-file-unix.c b/migration/qemu-file-unix.c index 1e7de7b..6b024e5 100644 --- a/migration/qemu-file-unix.c +++ b/migration/qemu-file-unix.c @@ -39,12 +39,43 @@ static ssize_t socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt, QEMUFileSocket *s = opaque; ssize_t len; ssize_t size = iov_size(iov, iovcnt); + ssize_t offset = 0; + int err; - len = iov_send(s->fd, iov, iovcnt, 0, size); - if (len < size) { - len = -socket_error(); - } - return len; + while (size > 0) { + len = iov_send(s->fd, iov, iovcnt, offset, size); + + if (len > 0) { + size -= len; + offset += len; + } + + if (size > 0) { + err = socket_error(); + + if (err != EAGAIN && err != EWOULDBLOCK) { + error_report("socket_writev_buffer: Got err=%d for (%zd/%zd)", + err, size, len); + /* + * If I've already sent some but only just got the error, I + * could return the amount validly sent so far and wait for the + * next call to report the error, but I'd rather flag the error + * immediately. + */ + return -err; + } + + /* Emulate blocking */ + GPollFD pfd; + + pfd.fd = s->fd; + pfd.events = G_IO_OUT | G_IO_ERR; + pfd.revents = 0; + g_poll(&pfd, 1 /* 1 fd */, -1 /* no timeout */); + } + } + + return offset; } static int socket_get_fd(void *opaque) -- 2.1.0