[RFC 4/4] switch non-standard SYSCALL_VECTOR allocation to use vector_irq[]

Dean Nelson
2008-09-11T15:29:50Z

Replace the current use of used_vectors[] for the allocation of a non-standard
SYSCALL_VECTOR by also using the per_cpu variable vector_irq[].

Signed-off-by: Dean Nelson <dcn@sgi.com>

---

arch/x86/kernel/traps_32.c | 17 +++++++++++------
drivers/lguest/interrupts_and_traps.c | 28 ++++++++++++++++++++++------
include/asm-x86/irq.h | 3 ---
3 files changed, 33 insertions(+), 15 deletions(-)

Index: linux/arch/x86/kernel/traps_32.c
===================================================================
--- linux.orig/arch/x86/kernel/traps_32.c 2008-09-10 14:25:23.000000000 -0500
+++ linux/arch/x86/kernel/traps_32.c 2008-09-10 14:25:28.000000000 -0500
@@ -63,9 +63,6 @@

#include "mach_traps.h"

-DECLARE_BITMAP(used_vectors, NR_VECTORS);
-EXPORT_SYMBOL_GPL(used_vectors);
-
asmlinkage int system_call(void);

/* Do we ignore FPU interrupts ? */
@@ -1189,6 +1186,8 @@ asmlinkage void math_emulate(long arg)
void __init trap_init(void)
{
int i;
+ bool ret;
+ unsigned long flags;

#ifdef CONFIG_EISA
void __iomem *p = early_ioremap(0x0FFFD9, 4);
@@ -1236,10 +1235,16 @@ void __init trap_init(void)
set_system_gate(SYSCALL_VECTOR, &system_call);

/* Reserve all the builtin and the syscall vector: */
- for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
- set_bit(i, used_vectors);
+ spin_lock_irqsave(&vector_lock, flags);
+ for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
+ ret =__grab_irq_vector(NON_IRQ_DESC, i, &cpu_possible_map);
+ BUG_ON(ret == false);
+ }

- set_bit(SYSCALL_VECTOR, used_vectors);
+ ret = __grab_irq_vector(NON_IRQ_DESC, SYSCALL_VECTOR,
+ &cpu_possible_map);
+ BUG_ON(ret == false);
+ spin_unlock_irqrestore(&vector_lock, flags);

/*
* Should be a barrier for any external CPU state:
Index: linux/include/asm-x86/irq.h
===================================================================
--- linux.orig/include/asm-x86/irq.h 2008-09-10 14:25:23.000000000 -0500
+++ linux/include/asm-x86/irq.h 2008-09-10 14:25:28.000000000 -0500
@@ -44,9 +44,6 @@ extern unsigned int do_IRQ(struct pt_reg
extern void init_IRQ(void);
extern void native_init_IRQ(void);

-/* Interrupt vector management */
-extern DECLARE_BITMAP(used_vectors, NR_VECTORS);
-
extern spinlock_t vector_lock;

#endif /* ASM_X86__IRQ_H */
Index: linux/drivers/lguest/interrupts_and_traps.c
===================================================================
--- linux.orig/drivers/lguest/interrupts_and_traps.c 2008-09-10 14:25:23.000000000 -0500
+++ linux/drivers/lguest/interrupts_and_traps.c 2008-09-10 14:25:28.000000000 -0500
@@ -221,19 +221,35 @@ bool check_syscall_vector(struct lguest

int init_interrupts(void)
{
+ unsigned long flags;
+ bool ret;
+
/* If they want some strange system call vector, reserve it now */
- if (syscall_vector != SYSCALL_VECTOR
- && test_and_set_bit(syscall_vector, used_vectors)) {
- printk("lg: couldn't reserve syscall %u\n", syscall_vector);
- return -EBUSY;
+ if (syscall_vector != SYSCALL_VECTOR) {
+ spin_lock_irqsave(&vector_lock, flags);
+ ret = __grab_irq_vector(NON_IRQ_DESC, syscall_vector,
+ &cpu_possible_map);
+ spin_unlock_irqrestore(&vector_lock, flags);
+ if (ret == false) {
+ printk("lg: couldn't reserve syscall %u\n",
+ syscall_vector);
+ return -EBUSY;
+ }
}
return 0;
}

void free_interrupts(void)
{
- if (syscall_vector != SYSCALL_VECTOR)
- clear_bit(syscall_vector, used_vectors);
+ int cpu;
+
+ if (syscall_vector != SYSCALL_VECTOR) {
+ for_each_cpu_mask_nr(cpu, cpu_possible_map) {
+ BUG_ON(per_cpu(vector_irq, cpu)[syscall_vector] !=
+ NON_IRQ_DESC);
+ per_cpu(vector_irq, cpu)[syscall_vector] = NULL;
+ }
+ }
}

/*H:220 Now we've got the routines to deliver interrupts, delivering traps like