Add thread-safety to kernel interrupt handler.

    The interrupt handling was originally written with the intent
    that only a single thread would receive interrupts.  We
    purposefully program the Interrupt Presenter hardware to
    route all interrupts to a single core.

    IPIs (Inter-processor Interrupts) are not routable by the ICP
    and end up being delivered to the targeted thread.  When we
    trigger a winkle-wakeup of a thread, that thread gets the IPI
    interrupt.  Since we broadcast the IPI to all threads on a core
    there is potential for multiple threads to be using the interrupt
    object at once.  Hence, we added a spinlock to protect it.

Change-Id: I736de774496b13cc9f344d389b9f249bbabeb036
Tested-by: Jenkins Server
Reviewed-by: Dean Sanner <dsanner@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/src/include/kernel/intmsghandler.H b/src/include/kernel/intmsghandler.H
index 88e1c2c1e..168b99d4a 100644
--- a/src/include/kernel/intmsghandler.H
+++ b/src/include/kernel/intmsghandler.H
@@ -68,15 +68,11 @@ class InterruptMsgHdlr : public MessageHandler
             MFRR_ADDR_OFFSET   = 12,
         };
 
-        // Notes:
-        //   All external interrupts are routed to one cpu core
-        //   External Interrupts are only processed one at a time
-        //   So we don't need a spinlock
         /**
          * Constructor
          */
         InterruptMsgHdlr(MessageQueue * i_msgQ)
-            : MessageHandler(NULL,i_msgQ) {}
+            : MessageHandler(&iv_lock,i_msgQ), iv_lock() {}
 
         /**
          * Destructor.
@@ -150,6 +146,8 @@ class InterruptMsgHdlr : public MessageHandler
 
         static InterruptMsgHdlr * cv_instance;
         static uint64_t cv_ipc_base_address;
+
+        Spinlock iv_lock;
 };