Patchwork [3.5.yuz,extended,stable] Patch "libceph: don't touch con state in con_close_socket()" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Nov. 20, 2012, 5:17 p.m.
Message ID <1353431828-9005-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/200442/
State New
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Comments

Herton Ronaldo Krzesinski - Nov. 20, 2012, 5:17 p.m.
This is a note to let you know that I have just added a patch titled

    libceph: don't touch con state in con_close_socket()

to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.yuz tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From 5ffc5bec29bbf13b957b210382b11e4d0f156e1d Mon Sep 17 00:00:00 2001
From: Alex Elder <elder@inktank.com>
Date: Wed, 20 Jun 2012 21:53:53 -0500
Subject: [PATCH 35/78] libceph: don't touch con state in con_close_socket()

commit 456ea46865787283088b23a8a7f69244513b95f0 upstream.

In con_close_socket(), a connection's SOCK_CLOSED flag gets set and
then cleared while its shutdown method is called and its reference
gets dropped.

Previously, that flag got set only if it had not already been set,
so setting it in con_close_socket() might have prevented additional
processing being done on a socket being shut down.  We no longer set
SOCK_CLOSED in the socket event routine conditionally, so setting
that bit here no longer provides whatever benefit it might have
provided before.

A race condition could still leave the SOCK_CLOSED bit set even
after we've issued the call to con_close_socket(), so we still clear
that bit after shutting the socket down.  Add a comment explaining
the reason for this.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 net/ceph/messenger.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--
1.7.9.5

Patch

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index cd1aaa8..dfff350 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -392,10 +392,16 @@  static int con_close_socket(struct ceph_connection *con)
 	dout("con_close_socket on %p sock %p\n", con, con->sock);
 	if (!con->sock)
 		return 0;
-	set_bit(SOCK_CLOSED, &con->flags);
 	rc = con->sock->ops->shutdown(con->sock, SHUT_RDWR);
 	sock_release(con->sock);
 	con->sock = NULL;
+
+	/*
+	 * Forcibly clear the SOCK_CLOSE flag.  It gets set
+	 * independent of the connection mutex, and we could have
+	 * received a socket close event before we had the chance to
+	 * shut the socket down.
+	 */
 	clear_bit(SOCK_CLOSED, &con->flags);
 	con_sock_state_closed(con);
 	return rc;