[PATCH 120/270] libceph: prevent the race of incoming work during teardown

[Herton Ronaldo Krzesinski]

3.5.7u1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guanjun He <gjhe at suse.com>

commit a2a3258417eb6a1799cf893350771428875a8287 upstream.

Add an atomic variable 'stopping' as flag in struct ceph_messenger,
set this flag to 1 in function ceph_destroy_client(), and add the condition code
in function ceph_data_ready() to test the flag value, if true(1), just return.

Signed-off-by: Guanjun He <gjhe at suse.com>
Reviewed-by: Sage Weil <sage at inktank.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 include/linux/ceph/messenger.h |    1 +
 net/ceph/ceph_common.c         |    2 ++
 net/ceph/messenger.c           |    5 +++++
 3 files changed, 8 insertions(+)

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index ec22abd..de39cda 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -50,6 +50,7 @@ struct ceph_messenger {
 	struct ceph_entity_inst inst;    /* my name+address */
 	struct ceph_entity_addr my_enc_addr;
 
+	atomic_t stopping;
 	bool nocrc;
 
 	/*
diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index 58b09ef..3b45e01 100644
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -495,6 +495,8 @@ void ceph_destroy_client(struct ceph_client *client)
 {
 	dout("destroy_client %p\n", client);
 
+	atomic_set(&client->msgr.stopping, 1);
+
 	/* unmount */
 	ceph_osdc_stop(&client->osdc);
 
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 16814d1..63e1252 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -254,6 +254,9 @@ static void con_sock_state_closed(struct ceph_connection *con)
 static void ceph_sock_data_ready(struct sock *sk, int count_unused)
 {
 	struct ceph_connection *con = sk->sk_user_data;
+	if (atomic_read(&con->msgr->stopping)) {
+		return;
+	}
 
 	if (sk->sk_state != TCP_CLOSE_WAIT) {
 		dout("%s on %p state = %lu, queueing work\n", __func__,
@@ -2413,6 +2416,8 @@ void ceph_messenger_init(struct ceph_messenger *msgr,
 	encode_my_addr(msgr);
 	msgr->nocrc = nocrc;
 
+	atomic_set(&msgr->stopping, 0);
+
 	dout("%s %p\n", __func__, msgr);
 }
 EXPORT_SYMBOL(ceph_messenger_init);
-- 
1.7.9.5