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Commit 022eb434 authored by Andrew Morton's avatar Andrew Morton Committed by Ingo Molnar
Browse files

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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 2c0b8a75

arch/x86/mm/highmem_32.c

+46 −1
Original line number Diff line number Diff line
@@ -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))