[PATCH][2.5] high irq count exceeds interrupt[] array (resend)

[Zwane Mwaikambo]

This patch is required to boot 2.4.70 on an 8quad NUMAQ, without it we 
exceed the interrupt stub array and end up programming random memory into 
the IDT.

Last time i posted this Linus asked what was wrong with vector collisions, 
i'll reply again; if we collide we end up overwriting the previous IDT 
entry and losing that irq entry.

(Hardware courtesy of OSDL)
Patch tested on 32way NUMAQ and uniprocessor with IOAPIC for regression.

Index: linux-2.5/include/asm-i386/mach-default/irq_vectors.h
===================================================================
RCS file: /home/cvs/linux-2.5/include/asm-i386/mach-default/irq_vectors.h,v
retrieving revision 1.3
diff -u -p -B -r1.3 irq_vectors.h
--- linux-2.5/include/asm-i386/mach-default/irq_vectors.h	8 Apr 2003 16:42:23 -0000	1.3
+++ linux-2.5/include/asm-i386/mach-default/irq_vectors.h	28 May 2003 23:50:52 -0000
@@ -74,9 +74,18 @@
  * more than 256 devices theoretically, but they will
  * have to use shared interrupts)
  * Since vectors 0x00-0x1f are used/reserved for the CPU,
- * the usable vector space is 0x20-0xff (224 vectors)
+ * the usable vector space is 0x20-0xff (224 vectors).
+ * Linux currently makes 189 vectors available for io interrupts
+ * starting at FIRST_DEVICE_VECTOR till FIRST_SYSTEM_VECTOR
+ * with 1 reserved for SYSCALL_VECTOR
+ * 
+ * 0________0x31__________________________0xef______0xff
+ *   system           io interrupts           resvd
+ *
  */
 #ifdef CONFIG_X86_IO_APIC
+/* number of vectors available for external devices */
+#define NR_IRQ_VECTORS	189
 #define NR_IRQS 224
 #else
 #define NR_IRQS 16
Index: linux-2.5/arch/i386/kernel/io_apic.c
===================================================================
RCS file: /home/cvs/linux-2.5/arch/i386/kernel/io_apic.c,v
retrieving revision 1.64
diff -u -p -B -r1.64 io_apic.c
--- linux-2.5/arch/i386/kernel/io_apic.c	15 May 2003 16:01:31 -0000	1.64
+++ linux-2.5/arch/i386/kernel/io_apic.c	28 May 2003 23:50:54 -0000
@@ -1120,9 +1120,15 @@ int irq_vector[NR_IRQS] = { FIRST_DEVICE
 
 static int __init assign_irq_vector(int irq)
 {
-	static int current_vector = FIRST_DEVICE_VECTOR, offset = 0;
+	static int current_vector = FIRST_DEVICE_VECTOR, offset = 0,
+		nr_assigned = 1;
+
 	if (IO_APIC_VECTOR(irq) > 0)
 		return IO_APIC_VECTOR(irq);
+
+	if (++nr_assigned > NR_IRQ_VECTORS)
+		return -ENOSPC;
+
 next:
 	current_vector += 8;
 	if (current_vector == SYSCALL_VECTOR)
@@ -1180,6 +1186,8 @@ void __init setup_IO_APIC_irqs(void)
 		}
 
 		irq = pin_2_irq(idx, apic, pin);
+		if (irq >= NR_IRQS)
+			continue;
 		/*
 		 * skip adding the timer int on secondary nodes, which causes
 		 * a small but painful rift in the time-space continuum
@@ -1194,6 +1202,9 @@ void __init setup_IO_APIC_irqs(void)
 
 		if (IO_APIC_IRQ(irq)) {
 			vector = assign_irq_vector(irq);
+			if (vector < 0)
+				continue;
+
 			entry.vector = vector;
 
 			if (IO_APIC_irq_trigger(irq))
@@ -2291,6 +2302,10 @@ int io_apic_set_pci_routing (int ioapic,
 {
 	struct IO_APIC_route_entry entry;
 	unsigned long flags;
+	int vector;
+
+	if (irq >= NR_IRQS)
+		return -ENOSPC;
 
 	if (!IO_APIC_IRQ(irq)) {
 		printk(KERN_ERR "IOAPIC[%d]: Invalid reference to IRQ 0/n", 
@@ -2315,8 +2330,11 @@ int io_apic_set_pci_routing (int ioapic,
 
 	add_pin_to_irq(irq, ioapic, pin);
 
-	entry.vector = assign_irq_vector(irq);
+	vector = assign_irq_vector(irq);
+	if (vector < 0)
+		return -ENOSPC;
 
+	entry.vector = vector;
 	printk(KERN_DEBUG "IOAPIC[%d]: Set PCI routing entry (%d-%d -> 0x%x -> "
 		"IRQ %d)\n", ioapic, 
 		mp_ioapics[ioapic].mpc_apicid, pin, entry.vector, irq);