1 files changed, 22 insertions, 12 deletions

diff --git a/drivers/misc/sgi-xp/xpc_sn2.c b/drivers/misc/sgi-xp/xpc_sn2.c
index 82fb9958f22f..2e975762c32b 100644
--- a/drivers/misc/sgi-xp/xpc_sn2.c
+++ b/drivers/misc/sgi-xp/xpc_sn2.c
@@ -1106,8 +1106,6 @@ xpc_process_activate_IRQ_rcvd_sn2(void)
         int n_IRQs_expected;
         int n_IRQs_detected;
 
-        DBUG_ON(xpc_activate_IRQ_rcvd == 0);
-
         spin_lock_irqsave(&xpc_activate_IRQ_rcvd_lock, irq_flags);
         n_IRQs_expected = xpc_activate_IRQ_rcvd;
         xpc_activate_IRQ_rcvd = 0;
@@ -1726,6 +1724,7 @@ xpc_clear_local_msgqueue_flags_sn2(struct xpc_channel *ch)
                 msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->local_msgqueue +
                                              (get % ch->local_nentries) *
                                              ch->entry_size);
+                DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
                 msg->flags = 0;
         } while (++get < ch_sn2->remote_GP.get);
 }
@@ -1740,11 +1739,18 @@ xpc_clear_remote_msgqueue_flags_sn2(struct xpc_channel *ch)
         struct xpc_msg_sn2 *msg;
         s64 put;
 
-        put = ch_sn2->w_remote_GP.put;
+        /* flags are zeroed when the buffer is allocated */
+        if (ch_sn2->remote_GP.put < ch->remote_nentries)
+                return;
+
+        put = max(ch_sn2->w_remote_GP.put, ch->remote_nentries);
         do {
                 msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->remote_msgqueue +
                                              (put % ch->remote_nentries) *
                                              ch->entry_size);
+                DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
+                DBUG_ON(!(msg->flags & XPC_M_SN2_DONE));
+                DBUG_ON(msg->number != put - ch->remote_nentries);
                 msg->flags = 0;
         } while (++put < ch_sn2->remote_GP.put);
 }
@@ -1836,6 +1842,7 @@ 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 +1941,7 @@ 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;
 
@@ -1956,11 +1963,13 @@ xpc_get_deliverable_payload_sn2(struct xpc_channel *ch)
 
                         msg = xpc_pull_remote_msg_sn2(ch, get);
 
-                        DBUG_ON(msg != NULL && msg->number != get);
-                        DBUG_ON(msg != NULL && (msg->flags & XPC_M_SN2_DONE));
-                        DBUG_ON(msg != NULL && !(msg->flags & XPC_M_SN2_READY));
+                        if (msg != NULL) {
+                                DBUG_ON(msg->number != get);
+                                DBUG_ON(msg->flags & XPC_M_SN2_DONE);
+                                DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
 
-                        payload = &msg->payload;
+                                payload = &msg->payload;
+                        }
                         break;
                 }
 
@@ -2053,7 +2062,7 @@ 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 +2195,7 @@ 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 */
 
@@ -2277,8 +2286,9 @@ xpc_received_payload_sn2(struct xpc_channel *ch, void *payload)
         dev_dbg(xpc_chan, "msg=0x%p, msg_number=%ld, partid=%d, channel=%d\n",
                 (void *)msg, msg_number, ch->partid, ch->number);
 
-        DBUG_ON((((u64)msg - (u64)ch->remote_msgqueue) / ch->entry_size) !=
+        DBUG_ON((((u64)msg - (u64)ch->sn.sn2.remote_msgqueue) / ch->entry_size) !=
                 msg_number % ch->remote_nentries);
+        DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
         DBUG_ON(msg->flags & XPC_M_SN2_DONE);
 
         msg->flags |= XPC_M_SN2_DONE;
@@ -2287,7 +2297,7 @@ 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