[PATCH] fix call of smp_processor_id() by XPC while preemptible

[dcn@sgi.com (Dean Nelson)]

XPC calls smp_processor_id() twice from xpc_setup_infrastructure() with
preemption enabled, which gets flagged if 'DEBUG_PREEMPT=y'. This patch
disables preemption around a now single call to smp_processor_id(). Note
that it doesn't matter if the thread is moved to another processor once
it has the processor ID.

Signed-off-by: Dean Nelson <dcn@sgi.com>


Index: linux-2.6/arch/ia64/sn/kernel/xpc_channel.c
=================================--- linux-2.6.orig/arch/ia64/sn/kernel/xpc_channel.c	2005-07-12 12:09:14.026288661 -0500
+++ linux-2.6/arch/ia64/sn/kernel/xpc_channel.c	2005-07-12 13:23:34.976151339 -0500
@@ -72,7 +72,7 @@
 enum xpc_retval
 xpc_setup_infrastructure(struct xpc_partition *part)
 {
-	int ret;
+	int ret, cpuid;
 	struct timer_list *timer;
 	partid_t partid = XPC_PARTID(part);
 
@@ -223,9 +223,13 @@
 	xpc_vars_part[partid].openclose_args_pa  					__pa(part->local_openclose_args);
 	xpc_vars_part[partid].IPI_amo_pa = __pa(part->local_IPI_amo_va);
-	xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(smp_processor_id());
-	xpc_vars_part[partid].IPI_phys_cpuid -					cpu_physical_id(smp_processor_id());
+
+	preempt_disable();
+	cpuid = smp_processor_id();
+	preempt_enable();
+	xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(cpuid);
+	xpc_vars_part[partid].IPI_phys_cpuid = cpu_physical_id(cpuid);
+
 	xpc_vars_part[partid].nchannels = part->nchannels;
 	xpc_vars_part[partid].magic = XPC_VP_MAGIC1;