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x86: kmap_atomic() debugging 

[ mingo@elte.hu: cleanups and made dependent on CONFIG_DEBUG_HIGHMEM.

  this caught a handful of bugs already, so lets apply it. If it gets
  things wrong we'll disable it. ]

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andrew Morton 2008-01-30 13:30:47 +01:00 committed by Ingo Molnar
parent 2c0b8a7578
commit 022eb43419
1 changed files with 46 additions and 1 deletions
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47
arch/x86/mm/highmem_32.c
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@ -18,6 +18,49 @@ void kunmap(struct page *page)
kunmap_high(page);
}
static void debug_kmap_atomic_prot(enum km_type type)
{
#ifdef CONFIG_DEBUG_HIGHMEM
static unsigned warn_count = 10;
if (unlikely(warn_count == 0))
return;
if (unlikely(in_interrupt())) {
if (in_irq()) {
if (type != KM_IRQ0 && type != KM_IRQ1 &&
type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
type != KM_BOUNCE_READ) {
WARN_ON(1);
warn_count--;
}
} else if (!irqs_disabled()) { /* softirq */
if (type != KM_IRQ0 && type != KM_IRQ1 &&
type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
type != KM_SKB_SUNRPC_DATA &&
type != KM_SKB_DATA_SOFTIRQ &&
type != KM_BOUNCE_READ) {
WARN_ON(1);
warn_count--;
}
}
}
if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) {
if (!irqs_disabled()) {
WARN_ON(1);
warn_count--;
}
} else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
if (irq_count() == 0 && !irqs_disabled()) {
WARN_ON(1);
warn_count--;
}
}
#endif
}
/*
* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
* no global lock is needed and because the kmap code must perform a global TLB
@ -30,8 +73,10 @@ void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
{
enum fixed_addresses idx;
unsigned long vaddr;
/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
debug_kmap_atomic_prot(type);
pagefault_disable();
if (!PageHighMem(page))