On Wednesday August 22, [EMAIL PROTECTED] wrote: > Chuck Ebbert <[EMAIL PROTECTED]> wrote: > > https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=253290 > > > > 18:57:54 osama kernel: [<c05be67f>] kernel_recvmsg+0x31/0x40 > > 18:57:54 osama kernel: [<e0bc52d4>] svc_udp_recvfrom+0x114/0x368 [sunrpc] > > svc_udp_recvfrom is calling kernel_recvmsg with iov == NULL.
iov == NULL used to work. I think it stopped working at commit 759e5d006462d53fb708daa8284b4ad909415da1 Previously, as len==0, MSG_TRUNC would get set, so copy_only would get set, so skb_copy_datagram_iovec would get called, and that handles a len of 0. Now, skb_copy_and_csum_datagram_iovec gets called unless skb_csum_unnecessary(skb), which now kills us. We could 'fix' it by making skb_copy_and_csum_datagram_iovec just return if len==0, or don't call it from udp_recvmsg in that case. The reason that I call kernel_recvmsg with iov == NULL is that I want to collect the source/dest addresses of the packet, but I don't want to actually read the data - I want to just get a reference to the skb (to avoid needless copy where possible) later. So I call kernel_recvmsg with MSG_PEEK, and don't bother with an iovec. I guess a could send an empty iovec rather than a NULL, but it used to work.... NeilBrown - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
