RFC: OpenPIC IPI patch

[Zbigniew Bodek]

On Wed, 30 May 2012 13:36:46 -0700, Marcel Moolenaar <marcel at xcllnt.net>
wrote:
> On May 30, 2012, at 1:13 PM, Rafal Jaworowski wrote:
> 
>> Can you please have a look at this patch and let us know about any
>> comments / objections? We identified a problem with IPI on the recent
FSL
>> eOpenPIC, description in the patch:
>> 
>> http://people.freebsd.org/~raj/patches/powerpc/openpic.diff
> 
> Looks good. Please consider adding some checks to openpic_ipi() where
> we peek into the cpuset_t type and access the "bits". An assert would
> be nice if the set contains cpus number 32 or up. This to make it
> painfully obvious that it's time to extend openpic_ipi() to handle more
> than 32 CPUs if and when the need arises.
> 
> FYI,

Indeed, there should be a sanity check in here.
I suggest the following assert:

diff --git a/sys/powerpc/powerpc/openpic.c b/sys/powerpc/powerpc/openpic.c
index 95af605..45858b6 100644
--- a/sys/powerpc/powerpc/openpic.c
+++ b/sys/powerpc/powerpc/openpic.c
@@ -29,6 +29,7 @@
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
+#include <sys/cpuset.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/rman.h>
@@ -344,8 +345,14 @@ void
openpic_ipi(device_t dev, cpuset_t cpumask)
{
	struct openpic_softc *sc;
+	cpuset_t ns_cpus;	/* Mask of not supported CPUs */
+
+	CPU_FILL(&ns_cpus);
+	ns_cpus.__bits[0] = 0;

	KASSERT(dev == root_pic, ("Cannot send IPIs from non-root OpenPIC"));
+	KASSERT(CPU_OVERLAP(&ns_cpus,  &cpumask) == 0,
+	    ("Cannot send an IPI to a CPU which number exceeds #31"));

	sc = device_get_softc(dev);
	sched_pin();

The patch is also available in the email's attachment.
Please send any comments and/or objections.

Best regards
Zbyszek Bodek
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ipi_assert.patch
Type: text/x-patch
Size: 798 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-ppc/attachments/20120531/b82913b2/ipi_assert.bin