From: Eric Dumazet Date: Sat, 28 Jan 2012 16:11:03 +0000 (+0000) Subject: af_unix: fix EPOLLET regression for stream sockets X-Git-Tag: v3.3-rc2~6^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f01fd6e6f6809061b56e78f1e8d143099716d70;p=pandora-kernel.git af_unix: fix EPOLLET regression for stream sockets Commit 0884d7aa24 (AF_UNIX: Fix poll blocking problem when reading from a stream socket) added a regression for epoll() in Edge Triggered mode (EPOLLET) Appropriate fix is to use skb_peek()/skb_unlink() instead of skb_dequeue(), and only call skb_unlink() when skb is fully consumed. This remove the need to requeue a partial skb into sk_receive_queue head and the extra sk->sk_data_ready() calls that added the regression. This is safe because once skb is given to sk_receive_queue, it is not modified by a writer, and readers are serialized by u->readlock mutex. This also reduce number of spinlock acquisition for small reads or MSG_PEEK users so should improve overall performance. Reported-by: Nick Mathewson Signed-off-by: Eric Dumazet Cc: Alexey Moiseytsev Signed-off-by: David S. Miller --- Reading git-diff-tree failed