Hello.
On 9/18/2015 7:04 PM, Aaron Conole wrote:
AF_UNIX sockets now return multiple skbs from recv() when MSG_PEEK flag
is set.
This is referenced in kernel bugzilla #12323 @
https://bugzilla.kernel.org/show_bug.cgi?id=12323
As described both in the BZ and lkml thread @
http://lkml.org/lkml/2008/1/8/444 calling recv() with MSG_PEEK on an
AF_UNIX socket only reads a single skb, where the desired effect is
to return as much skb data has been queued, until hitting the recv
buffer size (whichever comes first).
The modified MSG_PEEK path will now move to the next skb in the tree
and jump to the again: label, rather than following the natural loop
structure. This requires duplicating some of the loop head actions.
This was tested using the python socketpair() code attached to the
bugzilla issue.
Signed-off-by: Aaron Conole <acon...@bytheb.org>
Your patch doesn't comply to the Linux CodingStyle.
---
net/unix/af_unix.c | 17+-
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 03ee4d3..d2fd342 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2179,9 +2181,22 @@ unlock:
if (UNIXCB(skb).fp)
scm.fp = scm_fp_dup(UNIXCB(skb).fp);
- sk_peek_offset_fwd(sk, chunk);
+ if (skip)
+ {
if (skip) {
+ sk_peek_offset_fwd(sk, chunk);
+ skip -= chunk;
+ }
- break;
+ if (UNIXCB(skb).fp)
+ break;
+
+ /* XXX - this is ugly; better would be rewrite the
function */
+ last = skb;
+ last_len = skb->len;
+ unix_state_lock(&sk);
+ skb = skb_peek_next(skb, &sk->sk_receive_queue);
+ if (skb) goto again;
if (skb)
goto again;
+ goto unlock;
}
} while (size);
MBR, Sergei
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