Re: [PATCH] Fix interrupt distribution in ppc970

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On May 3, 2007, at 9:47 AM, Mohan Kumar M wrote:
On Thu, Apr 26, 2007 at 09:42:50AM -0500, Milton Miller wrote:
Yes.   The whole point of
-static int get_irq_server(unsigned int virq)
+static int get_irq_server(unsigned int virq, unsigned int
strict_check)
was to factor out the common code in this function.

Milton,

How about this patch?

Getting closer, still not right.


Index: linux-2.6.21.1/arch/powerpc/platforms/pseries/xics.c
===================================================================
--- linux-2.6.21.1.orig/arch/powerpc/platforms/pseries/xics.c
+++ linux-2.6.21.1/arch/powerpc/platforms/pseries/xics.c
@@ -156,9 +156,9 @@ static inline void lpar_qirr_info(int n_


 #ifdef CONFIG_SMP
-static int get_irq_server(unsigned int virq)
+static int get_irq_server(unsigned int virq, unsigned int strict_check)
 {
-	unsigned int server;
+	int server;
 	/* For the moment only implement delivery to all cpus or one cpu */
 	cpumask_t cpumask = irq_desc[virq].affinity;
 	cpumask_t tmp = CPU_MASK_NONE;
@@ -166,22 +166,28 @@ static int get_irq_server(unsigned int v
 	if (!distribute_irqs)
 		return default_server;

-	if (cpus_equal(cpumask, CPU_MASK_ALL)) {
-		server = default_distrib_server;
-	} else {
+	if (!cpus_equal(cpumask, CPU_MASK_ALL)) {
 		cpus_and(tmp, cpu_online_map, cpumask);

-		if (cpus_empty(tmp))
-			server = default_distrib_server;
+		server = first_cpu(tmp);
+
+		if (server < NR_CPUS)
+			return get_hard_smp_processor_id(server);
+		else {
+			if (strict_check)
+				return -1;


+			else
+				return default_distrib_server;
+		}
+	} else {

Take out the above 4 lines, so that the return always has cpu_online
vs cpu_present factored in, by falling through from specific mask to
default server selection.

+		if (cpus_equal(cpu_online_map, cpu_present_map))
+			return default_distrib_server;
 		else
-			server = get_hard_smp_processor_id(first_cpu(tmp));
+			return default_server;
 	}

[This matching brace will go and indent will change.]

-
-	return server;
-
 }
...

@@ -398,8 +404,7 @@ static void xics_set_affinity(unsigned i
 	unsigned int irq;
 	int status;
 	int xics_status[2];
-	unsigned long newmask;
-	cpumask_t tmp = CPU_MASK_NONE;
+	int irq_server;

 	irq = (unsigned int)irq_map[virq].hwirq;
 	if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
@@ -413,18 +418,28 @@ static void xics_set_affinity(unsigned i
 		return;
 	}

-	/* For the moment only implement delivery to all cpus or one cpu */
-	if (cpus_equal(cpumask, CPU_MASK_ALL)) {
-		newmask = default_distrib_server;
-	} else {
-		cpus_and(tmp, cpu_online_map, cpumask);
-		if (cpus_empty(tmp))
+	/* Get current irq_server for the given irq */
+	irq_server = get_irq_server(irq, 1);
+	if (irq_server == -1) {
+		printk(KERN_ERR "xics_set_affinity: Invalid cpumask\n");

WARNING or NOTICE would be fine. The interrupt number should be printed.
and maybe "No online cpus in <cpumask> for irq %d" would be better (I
think there is a print cpumask helper).

+		return;
+	}
+
+	/* For the moment only implement delivery to all cpus or one cpu.
+	 * Compare the irq_server with the new cpumask. If the irq_server
+	 * is specified in cpumask, do the required rtas_call, otherwise
+	 * return by printing an error message
+	 */
+	if (!cpus_equal(cpumask, CPU_MASK_ALL)) {
+		if (!cpu_isset(irq_server, cpumask)) {
+			printk(KERN_ERR "xics_set_affinity: Invalid "
+							"cpumask\n");
 			return;

I don't understand what you are trying to do here.  We already
chose the mask, and printed an error if we got -1 due to strict.
I think this can just be dropped?

-		newmask = get_hard_smp_processor_id(first_cpu(tmp));
+		}
 	}

 	status = rtas_call(ibm_set_xive, 3, 1, NULL,
-				irq, newmask, xics_status[1]);
+				irq, irq_server, xics_status[1]);

 	if (status) {
 		printk(KERN_ERR "xics_set_affinity: irq=%u ibm,set-xive "


milton

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