On Wed, Sep 20, 2017 at 5:09 PM, Jens Freimann <[email protected]> wrote: > On Tue, Sep 19, 2017 at 04:46:24PM +0000, Marc-Andr?? Lureau wrote: >> >> Hi >> >> On Tue, Aug 8, 2017 at 10:52 PM Jens Freimann <[email protected]> >> wrote: >>> >>> >>> From: Jens Freimann <[email protected]> >>> >>> End processing of messages when VHOST_USER_NONE >>> is received. >>> >>> Without this we run into a vubr_panic() call and get >>> "PANIC: Unhandled request: 0" >>> >>> Signed-off-by: Jens Freimann <[email protected]> >>> --- >>> contrib/libvhost-user/libvhost-user.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/contrib/libvhost-user/libvhost-user.c >>> b/contrib/libvhost-user/libvhost-user.c >>> index 9efb9dac0e..35fa0c5e56 100644 >>> --- a/contrib/libvhost-user/libvhost-user.c >>> +++ b/contrib/libvhost-user/libvhost-user.c >>> @@ -161,7 +161,7 @@ vu_message_read(VuDev *dev, int conn_fd, VhostUserMsg >>> *vmsg) >>> rc = recvmsg(conn_fd, &msg, 0); >>> } while (rc < 0 && (errno == EINTR || errno == EAGAIN)); >>> >>> - if (rc <= 0) { >>> + if (rc < 0) { >>> vu_panic(dev, "Error while recvmsg: %s", strerror(errno)); >>> return false; >>> } >>> @@ -806,6 +806,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg) >>> return vu_get_queue_num_exec(dev, vmsg); >>> case VHOST_USER_SET_VRING_ENABLE: >>> return vu_set_vring_enable_exec(dev, vmsg); >>> + case VHOST_USER_NONE: >>> + break; >> >> >> >> I am afraid this isn't working. vu_message_read() returns >> true/success, vu_process_message() returns false/no-reply, so >> vu_dispatch() will return success, and the caller has no clear way to >> know that the socket got disconnected. For me the vu_panic() was quite >> more appropriate here. >> >> What problem did this patch exactly solve? > > > The problem was that a VhostUserMsg of size 0 is considered an > error. But recvmsg() can return 0. When I ran my pxe
When did recvmsg() return 0? It should only be called after a poll IN/ERR, in case of data it should always return != 0, and if disconnected, it returns 0. > testcase using vhost-user-bridge I ran into vu_panic() because of this. > This worked because VHOST_USER_NONE is defined as 0. Instead of > doing this we could just allow a vmsg size of zero and not tread it > as an error? We want to treat disconnect as a panic condition imho, that the library user is free to implement in different way (abort() clean exit, reconnect etc). Please explain your use case and how you ran into recvmsg() = 0 and what you expect to happen at this point. -- Marc-André Lureau
