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

From: Dean Nelson <dcn_at_sgi.com>
Date: 2005-07-13 22:44:52
On Tue, Jul 12, 2005 at 09:47:54PM +0100, Christoph Hellwig wrote:
> On Tue, Jul 12, 2005 at 02:30:45PM -0500, Dean Nelson wrote:
> >  	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();
>
> just use __smp_processor_id() (or the fashionable name of the day)
> for it.

Tony, the revised patch follows.

Christoph, I assume this is what you meant.

Thanks,
Dean



XPC calls smp_processor_id() twice from xpc_setup_infrastructure() with
preemption enabled, which gets flagged if 'DEBUG_PREEMPT=y'. This patch
replaces the two calls to smp_processor_id() by a single call to
raw_smp_processor_id() since any CPU within the partition will do.

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	2005-07-13 06:48:14.408494167 -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 +223,9 @@
 	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());
+	cpuid = raw_smp_processor_id();	/* any CPU in this partition will do */
+	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;
 
-
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Received on Wed Jul 13 08:45:27 2005

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:40 EST