[IA64-SGI] enforce proper ordering of callouts by XPC

Fix XPC so that it does not deliver any messages until the connected
callout has returned, as well as, prevent the disconnected callout to
occur before the disconnecting callout has returned.

Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 18 insertions, 10 deletions

diff --git a/arch/ia64/sn/kernel/xpc_channel.c b/arch/ia64/sn/kernel/xpc_channel.c
index 36e5437a0fb6..cdf6856ce089 100644
--- a/arch/ia64/sn/kernel/xpc_channel.c
+++ b/arch/ia64/sn/kernel/xpc_channel.c
@@ -738,7 +738,9 @@ xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 
         /* make sure all activity has settled down first */
 
-        if (atomic_read(&ch->references) > 0) {
+        if (atomic_read(&ch->references) > 0 ||
+                        ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
+                        !(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE))) {
                 return;
         }
         DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
@@ -775,7 +777,7 @@ xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 
         /* both sides are disconnected now */
 
-        if (ch->flags & XPC_C_CONNECTCALLOUT) {
+        if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
                 xpc_disconnect_callout(ch, xpcDisconnected);
                 spin_lock_irqsave(&ch->lock, *irq_flags);
@@ -1300,7 +1302,7 @@ xpc_process_msg_IPI(struct xpc_partition *part, int ch_number)
                                 "delivered=%d, partid=%d, channel=%d\n",
                                 nmsgs_sent, ch->partid, ch->number);
 
-                        if (ch->flags & XPC_C_CONNECTCALLOUT) {
+                        if (ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) {
                                 xpc_activate_kthreads(ch, nmsgs_sent);
                         }
                 }
diff --git a/arch/ia64/sn/kernel/xpc_main.c b/arch/ia64/sn/kernel/xpc_main.c
index 9cd460dfe27e..8cbf16432570 100644
--- a/arch/ia64/sn/kernel/xpc_main.c
+++ b/arch/ia64/sn/kernel/xpc_main.c
@@ -750,12 +750,16 @@ xpc_daemonize_kthread(void *args)
                 /* let registerer know that connection has been established */
 
                 spin_lock_irqsave(&ch->lock, irq_flags);
-                if (!(ch->flags & XPC_C_CONNECTCALLOUT)) {
-                        ch->flags |= XPC_C_CONNECTCALLOUT;
+                if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
+                        ch->flags |= XPC_C_CONNECTEDCALLOUT;
                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 
                         xpc_connected_callout(ch);
 
+                        spin_lock_irqsave(&ch->lock, irq_flags);
+                        ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+
                         /*
                          * It is possible that while the callout was being
                          * made that the remote partition sent some messages.
@@ -777,15 +781,17 @@ xpc_daemonize_kthread(void *args)
 
         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
                 spin_lock_irqsave(&ch->lock, irq_flags);
-                if ((ch->flags & XPC_C_CONNECTCALLOUT) &&
-                                !(ch->flags & XPC_C_DISCONNECTCALLOUT)) {
-                        ch->flags |= XPC_C_DISCONNECTCALLOUT;
+                if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
+                                !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
+                        ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 
                         xpc_disconnect_callout(ch, xpcDisconnecting);
-                } else {
-                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+
+                        spin_lock_irqsave(&ch->lock, irq_flags);
+                        ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
                 }
+                spin_unlock_irqrestore(&ch->lock, irq_flags);
                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
                         xpc_mark_partition_disengaged(part);
                         xpc_IPI_send_disengage(part);