I'm not sure that I've gotten either the sctp or lockdep details right,
but with this patch I don't get lockdep yelling at me any more :)
------
sctp: lock_sock_nested in sctp_sock_migrate
sctp_sock_migrate() grabs the socket lock on a newly allocated socket while
holding the socket lock on an old socket. lockdep worries that this might
be a recursive lock attempt.
task/3026 is trying to acquire lock:
(sk_lock-AF_INET){--..}, at: [<ffffffff88105b8c>]
sctp_sock_migrate+0x2e3/0x327 [sctp]
but task is already holding lock:
(sk_lock-AF_INET){--..}, at: [<ffffffff8810891f>] sctp_accept+0xdf/0x1e3
[sctp]
This patch tells lockdep that this locking is safe by using
lock_sock_nested().
Signed-off-by: Zach Brown <[EMAIL PROTECTED]>
diff -r 8adcfdf2545b net/sctp/socket.c
--- a/net/sctp/socket.c Fri Jun 22 11:11:33 2007 -0700
+++ b/net/sctp/socket.c Fri Jun 22 15:05:22 2007 -0700
@@ -6084,8 +6084,11 @@ static void sctp_sock_migrate(struct soc
* queued to the backlog. This prevents a potential race between
* backlog processing on the old socket and new-packet processing
* on the new socket.
- */
- sctp_lock_sock(newsk);
+ *
+ * The caller has just allocated newsk so we can guarantee that other
+ * paths won't try to lock it and then oldsk.
+ */
+ lock_sock_nested(newsk, SINGLE_DEPTH_NESTING);
sctp_assoc_migrate(assoc, newsk);
/* If the association on the newsk is already closed before accept()
-
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