From 3e4d3af501cccdc8a8cca41bdbe57d54ad7e7e73 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 26 Oct 2010 14:21:51 -0700 Subject: mm: stack based kmap_atomic() Keep the current interface but ignore the KM_type and use a stack based approach. The advantage is that we get rid of crappy code like: #define __KM_PTE \ (in_nmi() ? KM_NMI_PTE : \ in_irq() ? KM_IRQ_PTE : \ KM_PTE0) and in general can stop worrying about what context we're in and what kmap slots might be appropriate for that. The downside is that FRV kmap_atomic() gets more expensive. For now we use a CPP trick suggested by Andrew: #define kmap_atomic(page, args...) __kmap_atomic(page) to avoid having to touch all kmap_atomic() users in a single patch. [ not compiled on: - mn10300: the arch doesn't actually build with highmem to begin with ] [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix up drivers/gpu/drm/i915/intel_overlay.c] Acked-by: Rik van Riel Signed-off-by: Peter Zijlstra Acked-by: Chris Metcalf Cc: David Howells Cc: Hugh Dickins Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Steven Rostedt Cc: Russell King Cc: Ralf Baechle Cc: David Miller Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Dave Airlie Cc: Li Zefan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/highmem.h | 61 +++++++++++++++++++++++++++++++------------------ 1 file changed, 39 insertions(+), 22 deletions(-) (limited to 'include/linux/highmem.h') diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 283cd47bb34c..8a85ec109a3a 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -28,18 +28,6 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size) #include -#ifdef CONFIG_DEBUG_HIGHMEM - -void debug_kmap_atomic(enum km_type type); - -#else - -static inline void debug_kmap_atomic(enum km_type type) -{ -} - -#endif - #ifdef CONFIG_HIGHMEM #include @@ -49,6 +37,27 @@ extern unsigned long totalhigh_pages; void kmap_flush_unused(void); +DECLARE_PER_CPU(int, __kmap_atomic_idx); + +static inline int kmap_atomic_idx_push(void) +{ + int idx = __get_cpu_var(__kmap_atomic_idx)++; +#ifdef CONFIG_DEBUG_HIGHMEM + WARN_ON_ONCE(in_irq() && !irqs_disabled()); + BUG_ON(idx > KM_TYPE_NR); +#endif + return idx; +} + +static inline int kmap_atomic_idx_pop(void) +{ + int idx = --__get_cpu_var(__kmap_atomic_idx); +#ifdef CONFIG_DEBUG_HIGHMEM + BUG_ON(idx < 0); +#endif + return idx; +} + #else /* CONFIG_HIGHMEM */ static inline unsigned int nr_free_highpages(void) { return 0; } @@ -66,19 +75,19 @@ static inline void kunmap(struct page *page) { } -static inline void *kmap_atomic(struct page *page, enum km_type idx) +static inline void *__kmap_atomic(struct page *page) { pagefault_disable(); return page_address(page); } -#define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx) +#define kmap_atomic_prot(page, prot) __kmap_atomic(page) -static inline void kunmap_atomic_notypecheck(void *addr, enum km_type idx) +static inline void __kunmap_atomic(void *addr) { pagefault_enable(); } -#define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx)) +#define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn)) #define kmap_atomic_to_page(ptr) virt_to_page(ptr) #define kmap_flush_unused() do {} while(0) @@ -86,12 +95,20 @@ static inline void kunmap_atomic_notypecheck(void *addr, enum km_type idx) #endif /* CONFIG_HIGHMEM */ -/* Prevent people trying to call kunmap_atomic() as if it were kunmap() */ -/* kunmap_atomic() should get the return value of kmap_atomic, not the page. */ -#define kunmap_atomic(addr, idx) do { \ - BUILD_BUG_ON(__same_type((addr), struct page *)); \ - kunmap_atomic_notypecheck((addr), (idx)); \ - } while (0) +/* + * Make both: kmap_atomic(page, idx) and kmap_atomic(page) work. + */ +#define kmap_atomic(page, args...) __kmap_atomic(page) + +/* + * Prevent people trying to call kunmap_atomic() as if it were kunmap() + * kunmap_atomic() should get the return value of kmap_atomic, not the page. + */ +#define kunmap_atomic(addr, args...) \ +do { \ + BUILD_BUG_ON(__same_type((addr), struct page *)); \ + __kunmap_atomic(addr); \ +} while (0) /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */ #ifndef clear_user_highpage -- cgit v1.2.3