[libvirt] [PATCHv2] macvtap: log an error if on failure to connect to netlink socket
Eric Blake
eblake at redhat.com
Wed Mar 16 16:31:44 UTC 2011
On 03/16/2011 10:02 AM, Laine Stump wrote:
> (v2 change: add log messages for 2 other previously silent error conditions in nlComm)
>
> A bug in libnl (see https://bugzilla.redhat.com/show_bug.cgi?id=677724
> and https://bugzilla.redhat.com/show_bug.cgi?id=677725) makes it very
> easy to create a failure to connect to the netlink socket when trying
> to open a macvtap network device ("type='direct'" in domain interface
> XML). When that error occurred (during a call to libnl's nl_connect()
> from libvirt's nlComm(), there was no log message, leading virsh (for
> example) to report "unknown error".
>
> There were two other cases in nlComm where an error in a libnl
> function might return with failure but no error reported. In all three
> cases, this patch logs a message which will hopefully be more useful.
>
> Note that more detailed information about the failure might be
> available from libnl's nl_geterror() function, but it calls
> strerror(), which is not threadsafe, so we can't use it.
Have we opened (yet another) libnl bug about that bad use of strerror()?
> ---
> src/util/macvtap.c | 13 ++++++++++---
> 1 files changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/src/util/macvtap.c b/src/util/macvtap.c
> index a71db86..00ee4ee 100644
> --- a/src/util/macvtap.c
> +++ b/src/util/macvtap.c
> @@ -123,10 +123,15 @@ int nlComm(struct nl_msg *nl_msg,
> struct nl_handle *nlhandle = nl_handle_alloc();
> struct nlmsghdr *nlmsg = nlmsg_hdr(nl_msg);
Swap these two lines, since nlmsg_hdr() might change errno...
>
> - if (!nlhandle)
> + if (!nlhandle) {
> + virReportSystemError(errno,
> + "%s", _("cannot allocate nlhandle for netlink"));
but you wanted the errno from nl_handle_alloc.
> return -1;
> + }
>
> if (nl_connect(nlhandle, NETLINK_ROUTE) < 0) {
> + virReportSystemError(errno,
> + "%s", _("cannot connect to netlink socket"));
> rc = -1;
> goto err_exit;
> }
> @@ -161,9 +166,11 @@ int nlComm(struct nl_msg *nl_msg,
> }
>
> *respbuflen = nl_recv(nlhandle, &nladdr, respbuf, NULL);
> - if (*respbuflen <= 0)
> + if (*respbuflen <= 0) {
> + virReportSystemError(errno,
> + "%s", _("nl_recv failed"));
> rc = -1;
> -
> + }
> err_exit:
> if (rc == -1) {
> VIR_FREE(*respbuf);
ACK with that nit fixed.
--
Eric Blake eblake at redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 619 bytes
Desc: OpenPGP digital signature
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20110316/6d78a588/attachment-0001.sig>
More information about the libvir-list
mailing list