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Date: Tue, 24 Jun 2008 18:38:07 +0200 From: "Julius Volz" <juliusv@...gle.com> To: netdev@...r.kernel.org Cc: "Patrick McHardy" <kaber@...sh.net>, "Vince Busam" <vbusam@...gle.com>, "Thomas Graf" <tgraf@...g.ch> Subject: Sending big Netlink messages to userspace Hi, While adding a Netlink interface to IPVS, I've been wondering how to properly send very big messages to userspace and found these posts: http://lists.openwall.net/netdev/2007/03/06/214 http://lists.openwall.net/netdev/2007/03/07/2 Herbert writes in the second one, "Dumps should be done using 4K (NLMSG_GOODSIZE) skb's, where is the problem?" How is that meant? Should one manually split up dumps into several NLMSG_GOODSIZE messages or is there some mechanism for that? I need to send arbitrarily long lists to userspace and I'm already choosing a big enough size for nlmsg_new(), so I get no put failures while constructing the message. However, when receiving the data in userspace (with libnl), the receive callback is never called. An strace shows that MSG_TRUNC is set in the oversized message, so the data is never fully received. I just call nl_recvmsgs_default(sock) once (which does not return an error). Am I handling libnl incorrectly or do I need to do this differently on the kernel side? Thanks, Julius -- Google Switzerland GmbH -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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