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Subject[patch 31/43] sgi-xpc: ensure flags are updated before bte_copy
2.6.28-stable review patch.  If anyone has any objections, please let us know.

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

From: Robin Holt <holt@sgi.com>

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@sgi.com>
Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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;

@@ -2060,7 +2061,7 @@ 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
@@ -2193,7 +2194,7 @@ 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 */

@@ -2294,7 +2295,7 @@ 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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