From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43986) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZuP1B-0007Wd-4h for qemu-devel@nongnu.org; Thu, 05 Nov 2015 13:12:14 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZuP1A-0003lY-4k for qemu-devel@nongnu.org; Thu, 05 Nov 2015 13:12:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43082) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZuP1A-0003lO-0C for qemu-devel@nongnu.org; Thu, 05 Nov 2015 13:12:12 -0500 From: "Dr. David Alan Gilbert (git)" Date: Thu, 5 Nov 2015 18:10:44 +0000 Message-Id: <1446747083-18205-18-git-send-email-dgilbert@redhat.com> In-Reply-To: <1446747083-18205-1-git-send-email-dgilbert@redhat.com> References: <1446747083-18205-1-git-send-email-dgilbert@redhat.com> Subject: [Qemu-devel] [PATCH v9 17/56] 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, liang.z.li@intel.com, luis@cs.umu.se, bharata@linux.vnet.ibm.com, amit.shah@redhat.com, pbonzini@redhat.com, david@gibson.dropbear.id.au 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 Reviewed-by: Amit Shah Reviewed-by: Juan Quintela --- migration/qemu-file-unix.c | 42 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 37 insertions(+), 5 deletions(-) diff --git a/migration/qemu-file-unix.c b/migration/qemu-file-unix.c index bcb744b..7ccdf69 100644 --- a/migration/qemu-file-unix.c +++ b/migration/qemu-file-unix.c @@ -22,6 +22,7 @@ * THE SOFTWARE. */ #include "qemu-common.h" +#include "qemu/error-report.h" #include "qemu/iov.h" #include "qemu/sockets.h" #include "qemu/coroutine.h" @@ -39,12 +40,43 @@ 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) -- 2.5.0