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SubjectRe: [RFC][Patch] fix for irq_affinity_write_proc v2.5
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> > I'd prefer to have it redesigned for some validity checking and error
> > returns as on such systems the impossible destinations serve no purpose
> > but raising MCE's and/or deadlocking the box.
>
> In which case I agree it does indeed make sense

As a matter of fact I have a patch that attempts to bring order to
set_ioapic_affinity the cause of the underlining problem for clustered
apics. I am not a big fan of the /proc interface because the values the
users sets and sees may or may not be the values written to the apic.
With kirqd running the user has no idea which cpu the irq is set to.
The user can be misinformed vi the /proc interface. The following patch
doesn't deal with this issue however. Maybe a later one will.
In the current kernel it is unclear as to weather the value being
passed to set_ioapic_affinity is a cpu mask or valid apic id. In
irq_affinity_write_proc the kernel passes on a cpu mask but the kirqd
thread passes on logical apic ids. In flat apic mode this is not an
issue because a cpu mask represents the apic value. However in
clustered apic mode the cpu mask is very different from the logical
apicid.
This is an attempt to do the right thing for clustered apics. I
clarify that the value being passed to set_ioapic_affinity is a cpu mask
not a apicid. Set_ioapic_affinity will do the conversion to logical
apic ids via a new function defined in the sub-arch called
cpu_mask_to_apicid. Since many cpu masks don't map to valid apicids in
clustered apic mode TARGET_CPUS is used as a default value when such a
situation occurs. I think this is a good step in making irq_affinity
clustered apic safe.

Keith

diff -urN linux-2.5.68/arch/i386/kernel/io_apic.c linux-2.5.68-fix_irq_affinity/arch/i386/kernel/io_apic.c
--- linux-2.5.68/arch/i386/kernel/io_apic.c Sat Apr 19 19:49:09 2003
+++ linux-2.5.68-fix_irq_affinity/arch/i386/kernel/io_apic.c Tue May 6 23:10:18 2003
@@ -240,22 +240,22 @@
clear_IO_APIC_pin(apic, pin);
}

-static void set_ioapic_affinity (unsigned int irq, unsigned long mask)
+static void set_ioapic_affinity (unsigned int irq, unsigned long cpu_mask)
{
unsigned long flags;
int pin;
struct irq_pin_list *entry = irq_2_pin + irq;
-
- /*
- * Only the first 8 bits are valid.
- */
- mask = mask << 24;
+ unsigned int apicid_value;
+
+ apicid_value = cpu_mask_to_apicid(cpu_mask);
+ /* Prepare to do the io_apic_write */
+ apicid_value = apicid_value << 24;
spin_lock_irqsave(&ioapic_lock, flags);
for (;;) {
pin = entry->pin;
if (pin == -1)
break;
- io_apic_write(entry->apic, 0x10 + 1 + pin*2, mask);
+ io_apic_write(entry->apic, 0x10 + 1 + pin*2, apicid_value);
if (!entry->next)
break;
entry = irq_2_pin + entry->next;
@@ -279,7 +279,7 @@

extern unsigned long irq_affinity[NR_IRQS];

-static int __cacheline_aligned pending_irq_balance_apicid[NR_IRQS];
+static int __cacheline_aligned pending_irq_balance_cpumask[NR_IRQS];
static int irqbalance_disabled = NO_BALANCE_IRQ;
static int physical_balance = 0;

@@ -352,7 +352,7 @@
unsigned long flags;

spin_lock_irqsave(&desc->lock, flags);
- pending_irq_balance_apicid[irq]=cpu_to_logical_apicid(new_cpu);
+ pending_irq_balance_cpumask[irq] = 1 << new_cpu;
spin_unlock_irqrestore(&desc->lock, flags);
}
}
@@ -549,8 +549,7 @@
selected_irq, min_loaded);
/* mark for change destination */
spin_lock_irqsave(&desc->lock, flags);
- pending_irq_balance_apicid[selected_irq] =
- cpu_to_logical_apicid(min_loaded);
+ pending_irq_balance_cpumask[selected_irq] = 1 << min_loaded;
spin_unlock_irqrestore(&desc->lock, flags);
/* Since we made a change, come back sooner to
* check for more variation.
@@ -582,7 +581,7 @@

/* push everything to CPU 0 to give us a starting point. */
for (i = 0 ; i < NR_IRQS ; i++)
- pending_irq_balance_apicid[i] = cpu_to_logical_apicid(0);
+ pending_irq_balance_cpumask[i] = 1;

repeat:
set_current_state(TASK_INTERRUPTIBLE);
@@ -659,9 +658,9 @@
static inline void move_irq(int irq)
{
/* note - we hold the desc->lock */
- if (unlikely(pending_irq_balance_apicid[irq])) {
- set_ioapic_affinity(irq, pending_irq_balance_apicid[irq]);
- pending_irq_balance_apicid[irq] = 0;
+ if (unlikely(pending_irq_balance_cpumask[irq])) {
+ set_ioapic_affinity(irq, pending_irq_balance_cpumask[irq]);
+ pending_irq_balance_cpumask[irq] = 0;
}
}

diff -urN linux-2.5.68/include/asm-i386/mach-bigsmp/mach_apic.h linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-bigsmp/mach_apic.h
--- linux-2.5.68/include/asm-i386/mach-bigsmp/mach_apic.h Sat Apr 19 19:51:08 2003
+++ linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-bigsmp/mach_apic.h Tue May 6 22:28:37 2003
@@ -27,7 +27,7 @@
#define APIC_BROADCAST_ID (0x0f)
#define check_apicid_used(bitmap, apicid) (0)
#define check_apicid_present(bit) (phys_cpu_present_map & (1 << bit))
-
+#define apicid_cluster(apicid) (apicid & 0xF0)
static inline unsigned long calculate_ldr(unsigned long old)
{
unsigned long id;
@@ -115,4 +115,37 @@
return (1);
}

+static inline unsigned int cpu_mask_to_apicid (unsigned long cpumask)
+{
+ int num_bits_set;
+ int cpus_found = 0;
+ int cpu;
+ int apicid;
+
+ num_bits_set = hweight32(cpumask);
+ /* Return id to all */
+ if (num_bits_set == 32)
+ return (int) 0xFF;
+ /*
+ * The cpus in the mask must all be on the apic cluster. If are not
+ * on the same apicid cluster return default value of TARGET_CPUS.
+ */
+ cpu = ffs(cpumask)-1;
+ apicid = cpu_to_logical_apicid(cpu);
+ while (cpus_found < num_bits_set) {
+ if (cpumask & (1 << cpu)) {
+ int new_apicid = cpu_to_logical_apicid(cpu);
+ if (apicid_cluster(apicid) !=
+ apicid_cluster(new_apicid)){
+ printk ("%s Not a valid mask! \n",__FUNCTION__);
+ return TARGET_CPUS;
+ }
+ apicid = apicid | new_apicid;
+ cpus_found++;
+ }
+ cpu++;
+ }
+ return apicid;
+}
+
#endif /* __ASM_MACH_APIC_H */
diff -urN linux-2.5.68/include/asm-i386/mach-default/mach_apic.h linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-default/mach_apic.h
--- linux-2.5.68/include/asm-i386/mach-default/mach_apic.h Sat Apr 19 19:51:19 2003
+++ linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-default/mach_apic.h Tue May 6 22:14:57 2003
@@ -99,4 +99,9 @@
return test_bit(boot_cpu_physical_apicid, &phys_cpu_present_map);
}

+static inline unsigned int cpu_mask_to_apicid (unsigned long cpumask)
+{
+ return cpumask;
+}
+
#endif /* __ASM_MACH_APIC_H */
diff -urN linux-2.5.68/include/asm-i386/mach-numaq/mach_apic.h linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-numaq/mach_apic.h
--- linux-2.5.68/include/asm-i386/mach-numaq/mach_apic.h Sat Apr 19 19:49:17 2003
+++ linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-numaq/mach_apic.h Tue May 6 22:51:02 2003
@@ -14,6 +14,7 @@
#define APIC_BROADCAST_ID 0x0F
#define check_apicid_used(bitmap, apicid) ((bitmap) & (1 << (apicid)))
#define check_apicid_present(bit) (phys_cpu_present_map & (1 << bit))
+#define apicid_cluster(apicid) (apicid & 0xF0)

static inline int apic_id_registered(void)
{
@@ -103,4 +104,37 @@
return (1);
}

+static inline unsigned int cpu_mask_to_apicid (unsigned long cpumask)
+{
+ int num_bits_set;
+ int cpus_found = 0;
+ int cpu;
+ int apicid;
+
+ num_bits_set = hweight32(cpumask);
+ /* Return id to all */
+ if (num_bits_set == 32)
+ return (int) 0xFF;
+ /*
+ * The cpus in the mask must all be on the apic cluster. If are not
+ * on the same apicid cluster return default value of TARGET_CPUS.
+ */
+ cpu = ffs(cpumask)-1;
+ apicid = cpu_to_logical_apicid(cpu);
+ while (cpus_found < num_bits_set) {
+ if (cpumask & (1 << cpu)) {
+ int new_apicid = cpu_to_logical_apicid(cpu);
+ if (apicid_cluster(apicid) !=
+ apicid_cluster(new_apicid)){
+ printk ("%s Not a valid mask! \n",__FUNCTION__);
+ return TARGET_CPUS;
+ }
+ apicid = apicid | new_apicid;
+ cpus_found++;
+ }
+ cpu++;
+ }
+ return apicid;
+}
+
#endif /* __ASM_MACH_APIC_H */
diff -urN linux-2.5.68/include/asm-i386/mach-summit/mach_apic.h linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-summit/mach_apic.h
--- linux-2.5.68/include/asm-i386/mach-summit/mach_apic.h Sat Apr 19 19:50:06 2003
+++ linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-summit/mach_apic.h Tue May 6 22:12:04 2003
@@ -23,7 +23,7 @@

/* we don't use the phys_cpu_present_map to indicate apicid presence */
#define check_apicid_present(bit) (x86_summit ? 1 : (phys_cpu_present_map & (1 << bit)))
-
+#define apicid_cluster(apicid) (apicid & 0xF0)
extern u8 bios_cpu_apicid[];

static inline void init_apic_ldr(void)
@@ -113,4 +113,37 @@
return test_bit(boot_cpu_physical_apicid, &phys_cpu_present_map);
}

+static inline unsigned int cpu_mask_to_apicid (unsigned long cpumask)
+{
+ int num_bits_set;
+ int cpus_found = 0;
+ int cpu;
+ int apicid;
+
+ num_bits_set = hweight32(cpumask);
+ /* Return id to all */
+ if (num_bits_set == 32)
+ return (int) 0xFF;
+ /*
+ * The cpus in the mask must all be on the apic cluster. If are not
+ * on the same apicid cluster return default value of TARGET_CPUS.
+ */
+ cpu = ffs(cpumask)-1;
+ apicid = cpu_to_logical_apicid(cpu);
+ while (cpus_found < num_bits_set) {
+ if (cpumask & (1 << cpu)) {
+ int new_apicid = cpu_to_logical_apicid(cpu);
+ if (apicid_cluster(apicid) !=
+ apicid_cluster(new_apicid)){
+ printk ("%s Not a valid mask! \n",__FUNCTION__);
+ return TARGET_CPUS;
+ }
+ apicid = apicid | new_apicid;
+ cpus_found++;
+ }
+ cpu++;
+ }
+ return apicid;
+}
+
#endif /* __ASM_MACH_APIC_H */
diff -urN linux-2.5.68/include/asm-i386/mach-visws/mach_apic.h linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-visws/mach_apic.h
--- linux-2.5.68/include/asm-i386/mach-visws/mach_apic.h Sat Apr 19 19:48:49 2003
+++ linux-2.5.68-fix_irq_affinity/include/asm-i386/mach-visws/mach_apic.h Tue May 6 22:16:52 2003
@@ -77,4 +77,8 @@
return test_bit(boot_cpu_physical_apicid, &phys_cpu_present_map);
}

+static inline unsigned int cpu_mask_to_apicid (unsigned long cpumask)
+{
+ return cpumask;
+}
#endif /* __ASM_MACH_APIC_H */
diff -urN linux-2.5.68/irq_proc_patch linux-2.5.68-fix_irq_affinity/irq_proc_patch
--- linux-2.5.68/irq_proc_patch Wed Dec 31 16:00:00 1969
+++ linux-2.5.68-fix_irq_affinity/irq_proc_patch Fri May 2 14:01:47 2003
@@ -0,0 +1,16 @@
+--- ../linux-2.5.68/arch/i386/kernel/irq.c Sat Apr 19 19:48:50 2003
++++ arch/i386/kernel/irq.c Fri May 2 14:01:12 2003
+@@ -871,8 +871,11 @@
+ return -EINVAL;
+
+ irq_affinity[irq] = new_value;
+- irq_desc[irq].handler->set_affinity(irq, new_value);
+-
++ if (irqbalance_disabled) {
++ irq_desc[irq].handler->set_affinity(irq, new_value);
++ } else {
++ do_irq_balance();
++ }
+ return full_count;
+ }
+

-
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