diff options
Diffstat (limited to 'include/linux/preempt_mask.h')
| -rw-r--r-- | include/linux/preempt_mask.h | 41 |
1 files changed, 30 insertions, 11 deletions
diff --git a/include/linux/preempt_mask.h b/include/linux/preempt_mask.h index d169820..931bc61 100644 --- a/include/linux/preempt_mask.h +++ b/include/linux/preempt_mask.h @@ -11,23 +11,36 @@ * - bits 0-7 are the preemption count (max preemption depth: 256) * - bits 8-15 are the softirq count (max # of softirqs: 256) * - * The hardirq count could in theory be the same as the number of - * interrupts in the system, but we run all interrupt handlers with - * interrupts disabled, so we cannot have nesting interrupts. Though - * there are a few palaeontologic drivers which reenable interrupts in - * the handler, so we need more than one bit here. + * The hardirq count can in theory reach the same as NR_IRQS. + * In reality, the number of nested IRQS is limited to the stack + * size as well. For archs with over 1000 IRQS it is not practical + * to expect that they will all nest. We give a max of 10 bits for + * hardirq nesting. An arch may choose to give less than 10 bits. + * m68k expects it to be 8. * - * PREEMPT_MASK: 0x000000ff - * SOFTIRQ_MASK: 0x0000ff00 - * HARDIRQ_MASK: 0x000f0000 - * NMI_MASK: 0x00100000 - * PREEMPT_ACTIVE: 0x00200000 + * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024) + * - bit 26 is the NMI_MASK + * - bit 27 is the PREEMPT_ACTIVE flag + * + * PREEMPT_MASK: 0x000000ff + * SOFTIRQ_MASK: 0x0000ff00 + * HARDIRQ_MASK: 0x03ff0000 + * NMI_MASK: 0x04000000 */ #define PREEMPT_BITS 8 #define SOFTIRQ_BITS 8 -#define HARDIRQ_BITS 4 #define NMI_BITS 1 +#define MAX_HARDIRQ_BITS 10 + +#ifndef HARDIRQ_BITS +# define HARDIRQ_BITS MAX_HARDIRQ_BITS +#endif + +#if HARDIRQ_BITS > MAX_HARDIRQ_BITS +#error HARDIRQ_BITS too high! +#endif + #define PREEMPT_SHIFT 0 #define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS) #define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS) @@ -47,9 +60,15 @@ #define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET) +#ifndef PREEMPT_ACTIVE #define PREEMPT_ACTIVE_BITS 1 #define PREEMPT_ACTIVE_SHIFT (NMI_SHIFT + NMI_BITS) #define PREEMPT_ACTIVE (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT) +#endif + +#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS)) +#error PREEMPT_ACTIVE is too low! +#endif #define hardirq_count() (preempt_count() & HARDIRQ_MASK) #define softirq_count() (preempt_count() & SOFTIRQ_MASK) |