[libvirt] [PATCH] macvtap: log an error if on failure to connect to netlink socket
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, there was no log message, leading virsh (for example) to report "unknown error". This patch logs a message which will hopefully be more useful. (All other error exits from the same function were already logging a message). --- src/util/macvtap.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/src/util/macvtap.c b/src/util/macvtap.c index a71db86..66bdc73 100644 --- a/src/util/macvtap.c +++ b/src/util/macvtap.c @@ -127,6 +127,8 @@ int nlComm(struct nl_msg *nl_msg, return -1; if (nl_connect(nlhandle, NETLINK_ROUTE) < 0) { + virReportSystemError(errno, + "%s", _("cannot connect to netlink socket")); rc = -1; goto err_exit; } -- 1.7.3.4
On 03/15/2011 02:32 PM, Laine Stump wrote: In the subject, s/if //
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, there was no log message, leading virsh (for example) to report "unknown error".
This patch logs a message which will hopefully be more useful. (All other error exits from the same function were already logging a message).
Well, not all of them - nl_handle_alloc failure was silent instead of calling virReportOOMError before returning -1. Likewise for the final nl_recv not calling virReportSystemError.
--- src/util/macvtap.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/src/util/macvtap.c b/src/util/macvtap.c index a71db86..66bdc73 100644 --- a/src/util/macvtap.c +++ b/src/util/macvtap.c @@ -127,6 +127,8 @@ int nlComm(struct nl_msg *nl_msg, return -1;
if (nl_connect(nlhandle, NETLINK_ROUTE) < 0) { + virReportSystemError(errno, + "%s", _("cannot connect to netlink socket")); rc = -1; goto err_exit;
What you have is good, but you may want to also scrub those two other failure paths to issue an error and post a v2. -- Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
On 03/15/2011 04:45 PM, Eric Blake wrote:
On 03/15/2011 02:32 PM, Laine Stump wrote:
In the subject, s/if //
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, there was no log message, leading virsh (for example) to report "unknown error".
This patch logs a message which will hopefully be more useful. (All other error exits from the same function were already logging a message). Well, not all of them - nl_handle_alloc failure was silent instead of calling virReportOOMError before returning -1. Likewise for the final nl_recv not calling virReportSystemError.
Ah right, I see what you mean. I hadn't looked as closely, just at the "goto err_exit" places. I'll do a V2 later tonight. Right now the front door is opening...
(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. --- 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); - if (!nlhandle) + if (!nlhandle) { + virReportSystemError(errno, + "%s", _("cannot allocate nlhandle for netlink")); 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); -- 1.7.3.4
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@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
On 03/15/2011 04:32 PM, Laine Stump wrote:
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, there was no log message, leading virsh (for example) to report "unknown error".
This patch logs a message which will hopefully be more useful. (All other error exits from the same function were already logging a message). --- src/util/macvtap.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/src/util/macvtap.c b/src/util/macvtap.c index a71db86..66bdc73 100644 --- a/src/util/macvtap.c +++ b/src/util/macvtap.c @@ -127,6 +127,8 @@ int nlComm(struct nl_msg *nl_msg, return -1;
if (nl_connect(nlhandle, NETLINK_ROUTE)< 0) { + virReportSystemError(errno, + "%s", _("cannot connect to netlink socket")); rc = -1; goto err_exit; } ACK
Stefan
participants (3)
-
Eric Blake -
Laine Stump -
Stefan Berger