diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 3c1e1611b0..00256fa318 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -296,15 +296,27 @@ static int vhost_user_read_header(struct vhost_dev *dev, VhostUserMsg *msg) return 0; } -static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg) +struct vhost_user_read_cb_data { + struct vhost_dev *dev; + VhostUserMsg *msg; + GMainLoop *loop; + int ret; +}; + +static gboolean vhost_user_read_cb(GIOChannel *source, GIOCondition condition, + gpointer opaque) { + struct vhost_user_read_cb_data *data = opaque; + struct vhost_dev *dev = data->dev; + VhostUserMsg *msg = data->msg; struct vhost_user *u = dev->opaque; CharBackend *chr = u->user->chr; uint8_t *p = (uint8_t *) msg; int r, size; if (vhost_user_read_header(dev, msg) < 0) { - return -1; + data->ret = -1; + goto end; } /* validate message size is sane */ @@ -312,7 +324,8 @@ static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg) error_report("Failed to read msg header." " Size %d exceeds the maximum %zu.", msg->hdr.size, VHOST_USER_PAYLOAD_SIZE); - return -1; + data->ret = -1; + goto end; } if (msg->hdr.size) { @@ -322,11 +335,53 @@ static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg) if (r != size) { error_report("Failed to read msg payload." " Read %d instead of %d.", r, msg->hdr.size); - return -1; + data->ret = -1; + goto end; } } - return 0; +end: + g_main_loop_quit(data->loop); + return G_SOURCE_REMOVE; +} + +static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg) +{ + struct vhost_user *u = dev->opaque; + CharBackend *chr = u->user->chr; + GMainContext *prev_ctxt = chr->chr->gcontext; + GMainContext *ctxt = g_main_context_new(); + GMainLoop *loop = g_main_loop_new(ctxt, FALSE); + struct vhost_user_read_cb_data data = { + .dev = dev, + .loop = loop, + .msg = msg, + .ret = 0 + }; + + /* + * We want to be able to monitor the slave channel fd while waiting + * for chr I/O. This requires an event loop, but we can't nest the + * one to which chr is currently attached : its fd handlers might not + * be prepared for re-entrancy. So we create a new one and switch chr + * to use it. + */ + qemu_chr_be_update_read_handlers(chr->chr, ctxt); + qemu_chr_fe_add_watch(chr, G_IO_IN | G_IO_HUP, vhost_user_read_cb, &data); + + g_main_loop_run(loop); + + /* + * Restore the previous event loop context. This also destroys/recreates + * event sources : this guarantees that all pending events in the original + * context that have been processed by the nested loop are purged. + */ + qemu_chr_be_update_read_handlers(chr->chr, prev_ctxt); + + g_main_loop_unref(loop); + g_main_context_unref(ctxt); + + return data.ret; } static int process_message_reply(struct vhost_dev *dev,