[IA64] MCA recovery improvements

Jack Steiner uncovered some opportunities for improvement in
the MCA recovery code.

  1) Set bsp to save registers on the kernel stack.
  2) Disable interrupts while in the MCA recovery code.
  3) Change the way the user process is killed, to avoid 
     a panic in schedule.

Testing shows that these changes make the recovery code much 
more reliable with the 2.6.12 kernel.

Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/mca_drv.c b/arch/ia64/kernel/mca_drv.c
index ab47817..abc0113 100644
--- a/arch/ia64/kernel/mca_drv.c
+++ b/arch/ia64/kernel/mca_drv.c
@@ -132,8 +132,7 @@
 	spin_unlock(&mca_bh_lock);
 
 	/* This process is about to be killed itself */
-	force_sig(SIGKILL, current);
-	schedule();
+	do_exit(SIGKILL);
 }
 
 /**
@@ -439,6 +438,7 @@
 			psr2 = (struct ia64_psr *)&pmsa->pmsa_ipsr;
 			psr2->cpl = 0;
 			psr2->ri  = 0;
+			psr2->i  = 0;
 
 			return 1;
 		}