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.
> 
> I wasn't trying to change the prototype of xics_set_affinity.
> 
> Looking at the code a bit, I think part of the confusion is that newmask
> is horribly misnamed.   Please rename it to server or irqserver.
> Obtain its value by calling get_irq_server.  If the server returned
> is -1 (in strict mode), don't call rtas (just return like today).
> I guess a printk could be in order since the function is void, and
> only root can request the change.

Milton,

How about this patch?


It is observed that in some PPC970 based machines, When the kernel is
booted with maxcpus=1, interrupts were distributed to offline cpus
also. So a condition is included to check whether the cpu online
map and cpu present map are equal or not. If they are equal
default_distrib_server is used as the interrupt server otherwise
default_server(ie boot cpu) is used as the interrupt server.

In addition to this, if an interrupt is assigned to a specific cpu (ie
smp affinity) and if that cpu is not online, the earlier code used to
return the default_distrib_server as interrupt server. This patch
introduces an additional paramter to the get_irq function ie
strict_check, based on this parameter, if the cpu is not online either
default_distrib_server or -1 is returned.

Cc: Milton Miller <[EMAIL PROTECTED]>,
    Michael Ellerman <[EMAIL PROTECTED]>
Signed-off-by: Mohan Kumar M <[EMAIL PROTECTED]>
---
 arch/powerpc/platforms/pseries/xics.c |   63 +++++++++++++++++++++-------------
 1 file changed, 39 insertions(+), 24 deletions(-)

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 {
+               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;
        }
-
-       return server;
-
 }
 #else
-static int get_irq_server(unsigned int virq)
+static int get_irq_server(unsigned int virq, unsigned int strict_check)
 {
        return default_server;
 }
@@ -192,7 +198,7 @@ static void xics_unmask_irq(unsigned int
 {
        unsigned int irq;
        int call_status;
-       unsigned int server;
+       int server;
 
        pr_debug("xics: unmask virq %d\n", virq);
 
@@ -201,7 +207,7 @@ static void xics_unmask_irq(unsigned int
        if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
                return;
 
-       server = get_irq_server(virq);
+       server = get_irq_server(virq, 0);
 
        call_status = rtas_call(ibm_set_xive, 3, 1, NULL, irq, server,
                                DEFAULT_PRIORITY);
@@ -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");
+               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;
-               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 "
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