sgi-xpc: ensure flags are updated before bte_copy

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>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 5 deletions

diff --git a/drivers/misc/sgi-xp/xpc_sn2.c b/drivers/misc/sgi-xp/xpc_sn2.c
index 82fb9958f22f..7aafb8a91945 100644
--- a/drivers/misc/sgi-xp/xpc_sn2.c
+++ b/drivers/misc/sgi-xp/xpc_sn2.c
@@ -1836,6 +1836,7 @@ xpc_process_msg_chctl_flags_sn2(struct xpc_partition *part, int ch_number)
                  */
                 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, "
@@ -1934,7 +1935,7 @@ xpc_get_deliverable_payload_sn2(struct xpc_channel *ch)
                         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;
 
@@ -2053,7 +2054,7 @@ xpc_allocate_msg_sn2(struct xpc_channel *ch, u32 flags,
         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
@@ -2186,7 +2187,7 @@ xpc_send_payload_sn2(struct xpc_channel *ch, u32 flags, void *payload,
          * 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 */
 
@@ -2287,7 +2288,7 @@ xpc_received_payload_sn2(struct xpc_channel *ch, void *payload)
          * 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
diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
index 91a55b1b1037..f17f7d40ea2c 100644
--- a/drivers/misc/sgi-xp/xpc_uv.c
+++ b/drivers/misc/sgi-xp/xpc_uv.c
@@ -1423,7 +1423,7 @@ xpc_send_payload_uv(struct xpc_channel *ch, u32 flags, void *payload,
                 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) {