[patch 27/32] sgi-xpc: ensure flags are updated before bte_copy

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

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

From: Robin Holt <holt@xxxxxxx>

commit 69b3bb65fa97a1e8563518dbbc35cd57beefb2d4 upstream.

The clearing of the msg->flags needs a barrier between it and the notify
of the channel threads that the messages are cleaned and ready for use.

Signed-off-by: Robin Holt <holt@xxxxxxx>
Signed-off-by: Dean Nelson <dcn@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/misc/sgi-xp/xpc_sn2.c |    9 +++++----
 drivers/misc/sgi-xp/xpc_uv.c  |    2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/misc/sgi-xp/xpc_sn2.c
+++ b/drivers/misc/sgi-xp/xpc_sn2.c
@@ -1841,6 +1841,7 @@ xpc_process_msg_chctl_flags_sn2(struct x
 		 */
 		xpc_clear_remote_msgqueue_flags_sn2(ch);
 
+		smp_wmb(); /* ensure flags have been cleared before bte_copy */
 		ch_sn2->w_remote_GP.put = ch_sn2->remote_GP.put;
 
 		dev_dbg(xpc_chan, "w_remote_GP.put changed to %ld, partid=%d, "
@@ -1939,7 +1940,7 @@ xpc_get_deliverable_payload_sn2(struct x
 			break;
 
 		get = ch_sn2->w_local_GP.get;
-		rmb();	/* guarantee that .get loads before .put */
+		smp_rmb();	/* guarantee that .get loads before .put */
 		if (get == ch_sn2->w_remote_GP.put)
 			break;
 
@@ -2058,7 +2059,7 @@ xpc_allocate_msg_sn2(struct xpc_channel 
 	while (1) {
 
 		put = ch_sn2->w_local_GP.put;
-		rmb();	/* guarantee that .put loads before .get */
+		smp_rmb();	/* guarantee that .put loads before .get */
 		if (put - ch_sn2->w_remote_GP.get < ch->local_nentries) {
 
 			/* There are available message entries. We need to try
@@ -2191,7 +2192,7 @@ xpc_send_payload_sn2(struct xpc_channel 
 	 * The preceding store of msg->flags must occur before the following
 	 * load of local_GP->put.
 	 */
-	mb();
+	smp_mb();
 
 	/* see if the message is next in line to be sent, if so send it */
 
@@ -2292,7 +2293,7 @@ xpc_received_payload_sn2(struct xpc_chan
 	 * The preceding store of msg->flags must occur before the following
 	 * load of local_GP->get.
 	 */
-	mb();
+	smp_mb();
 
 	/*
 	 * See if this message is next in line to be acknowledged as having
--- a/drivers/misc/sgi-xp/xpc_uv.c
+++ b/drivers/misc/sgi-xp/xpc_uv.c
@@ -1238,7 +1238,7 @@ xpc_send_payload_uv(struct xpc_channel *
 		atomic_inc(&ch->n_to_notify);
 
 		msg_slot->key = key;
-		wmb(); /* a non-NULL func must hit memory after the key */
+		smp_wmb(); /* a non-NULL func must hit memory after the key */
 		msg_slot->func = func;
 
 		if (ch->flags & XPC_C_DISCONNECTING) {

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