From 60bf942a58db12c821f2a6a49e2e0b04b99bec30 Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Mon, 20 Jun 2022 02:39:42 -0300 Subject: [PATCH 15/18] QIOChannelSocket: Introduce assert and reduce ifdefs to improve readability MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Leonardo Brás RH-MergeRequest: 95: MSG_ZEROCOPY + Multifd RH-Commit: [9/11] eaa02d68301852ccc98bdacc7387d8d03be1cb05 (LeoBras/centos-qemu-kvm) RH-Bugzilla: 1968509 RH-Acked-by: Miroslav Rezanina RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Peter Xu During implementation of MSG_ZEROCOPY feature, a lot of #ifdefs were introduced, particularly at qio_channel_socket_writev(). Rewrite some of those changes so it's easier to read. Also, introduce an assert to help detect incorrect zero-copy usage is when it's disabled on build. Signed-off-by: Leonardo Bras Reviewed-by: Daniel P. Berrangé Reviewed-by: Juan Quintela Reviewed-by: Peter Xu Signed-off-by: Juan Quintela Signed-off-by: Dr. David Alan Gilbert dgilbert: Fixed up thinko'd g_assert_unreachable->g_assert_not_reached (cherry picked from commit 803ca43e4c7fcf32f9f68c118301ccd0c83ece3f) Signed-off-by: Leonardo Bras --- io/channel-socket.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/io/channel-socket.c b/io/channel-socket.c index fbd2214d20..7490e5943d 100644 --- a/io/channel-socket.c +++ b/io/channel-socket.c @@ -579,11 +579,17 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc, memcpy(CMSG_DATA(cmsg), fds, fdsize); } -#ifdef QEMU_MSG_ZEROCOPY if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) { +#ifdef QEMU_MSG_ZEROCOPY sflags = MSG_ZEROCOPY; - } +#else + /* + * We expect QIOChannel class entry point to have + * blocked this code path already + */ + g_assert_not_reached(); #endif + } retry: ret = sendmsg(sioc->fd, &msg, sflags); @@ -593,15 +599,13 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc, return QIO_CHANNEL_ERR_BLOCK; case EINTR: goto retry; -#ifdef QEMU_MSG_ZEROCOPY case ENOBUFS: - if (sflags & MSG_ZEROCOPY) { + if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) { error_setg_errno(errp, errno, "Process can't lock enough memory for using MSG_ZEROCOPY"); return -1; } break; -#endif } error_setg_errno(errp, errno, -- 2.35.3