Right now slave_read() is called through main event loop and does not return error. In next few patches I want to call slave_read() from vhost device shutdown path as well and want to know if an error happened so that caller can give up and return error accordingly.
Hence, create helper function do_slave_read(), which returns an integer. Success is 0 and negative number is error code. slave_read() calls do_slave_read() and ignores error code. Signed-off-by: Vivek Goyal <vgo...@redhat.com> --- hw/virtio/vhost-user.c | 43 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 6 deletions(-) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index d95dbc39e3..867cac034f 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -1401,7 +1401,7 @@ static uint64_t vhost_user_slave_handle_vring_host_notifier( return false; } -static void slave_read(void *opaque) +static int do_slave_read(void *opaque) { struct vhost_dev *dev = opaque; struct vhost_user *u = dev->opaque; @@ -1432,13 +1432,22 @@ static void slave_read(void *opaque) size = recvmsg(u->slave_fd, &msgh, 0); } while (size < 0 && (errno == EINTR || errno == EAGAIN)); - if (size != VHOST_USER_HDR_SIZE) { + if (size < 0) { + ret = -errno; error_report("Failed to read from slave."); goto err; } + if (size != VHOST_USER_HDR_SIZE) { + error_report("Failed to read %lu bytes from slave.", + VHOST_USER_HDR_SIZE); + ret = -EBADMSG; + goto err; + } + if (msgh.msg_flags & MSG_CTRUNC) { error_report("Truncated message."); + ret = -EBADMSG; goto err; } @@ -1456,6 +1465,7 @@ static void slave_read(void *opaque) error_report("Failed to read msg header." " Size %d exceeds the maximum %zu.", hdr.size, VHOST_USER_PAYLOAD_SIZE); + ret = -EBADMSG; goto err; } @@ -1464,8 +1474,15 @@ static void slave_read(void *opaque) size = read(u->slave_fd, &payload, hdr.size); } while (size < 0 && (errno == EINTR || errno == EAGAIN)); - if (size != hdr.size) { + if (size == -1) { error_report("Failed to read payload from slave."); + ret = errno; + goto err; + } + + if (size != hdr.size) { + error_report("Failed to read %d payload bytes from slave.", hdr.size); + ret = -EBADMSG; goto err; } @@ -1529,13 +1546,22 @@ static void slave_read(void *opaque) size = writev(u->slave_fd, iovec, ARRAY_SIZE(iovec)); } while (size < 0 && (errno == EINTR || errno == EAGAIN)); - if (size != VHOST_USER_HDR_SIZE + hdr.size) { + if (size == -1) { error_report("Failed to send msg reply to slave."); + ret = -errno; + goto err; + } + + if (size != VHOST_USER_HDR_SIZE + hdr.size) { + error_report("Failed to send msg reply to slave. Wrote %d bytes" + " expected %lu bytes.", size, + VHOST_USER_HDR_SIZE + hdr.size); + ret = -EIO; goto err; } } - return; + return 0; err: qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL); @@ -1546,7 +1572,12 @@ err: close(fd[i]); } } - return; + return ret; +} + +static void slave_read(void *opaque) +{ + do_slave_read(opaque); } static int vhost_setup_slave_channel(struct vhost_dev *dev) -- 2.25.4