diff options
Diffstat (limited to 'include/linux/page_ref.h')
| -rw-r--r-- | include/linux/page_ref.h | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h new file mode 100644 index 000000000000..e596d5d9540e --- /dev/null +++ b/include/linux/page_ref.h @@ -0,0 +1,173 @@ +#ifndef _LINUX_PAGE_REF_H +#define _LINUX_PAGE_REF_H + +#include <linux/atomic.h> +#include <linux/mm_types.h> +#include <linux/page-flags.h> +#include <linux/tracepoint-defs.h> + +extern struct tracepoint __tracepoint_page_ref_set; +extern struct tracepoint __tracepoint_page_ref_mod; +extern struct tracepoint __tracepoint_page_ref_mod_and_test; +extern struct tracepoint __tracepoint_page_ref_mod_and_return; +extern struct tracepoint __tracepoint_page_ref_mod_unless; +extern struct tracepoint __tracepoint_page_ref_freeze; +extern struct tracepoint __tracepoint_page_ref_unfreeze; + +#ifdef CONFIG_DEBUG_PAGE_REF + +/* + * Ideally we would want to use the trace_<tracepoint>_enabled() helper + * functions. But due to include header file issues, that is not + * feasible. Instead we have to open code the static key functions. + * + * See trace_##name##_enabled(void) in include/linux/tracepoint.h + */ +#define page_ref_tracepoint_active(t) static_key_false(&(t).key) + +extern void __page_ref_set(struct page *page, int v); +extern void __page_ref_mod(struct page *page, int v); +extern void __page_ref_mod_and_test(struct page *page, int v, int ret); +extern void __page_ref_mod_and_return(struct page *page, int v, int ret); +extern void __page_ref_mod_unless(struct page *page, int v, int u); +extern void __page_ref_freeze(struct page *page, int v, int ret); +extern void __page_ref_unfreeze(struct page *page, int v); + +#else + +#define page_ref_tracepoint_active(t) false + +static inline void __page_ref_set(struct page *page, int v) +{ +} +static inline void __page_ref_mod(struct page *page, int v) +{ +} +static inline void __page_ref_mod_and_test(struct page *page, int v, int ret) +{ +} +static inline void __page_ref_mod_and_return(struct page *page, int v, int ret) +{ +} +static inline void __page_ref_mod_unless(struct page *page, int v, int u) +{ +} +static inline void __page_ref_freeze(struct page *page, int v, int ret) +{ +} +static inline void __page_ref_unfreeze(struct page *page, int v) +{ +} + +#endif + +static inline int page_ref_count(struct page *page) +{ + return atomic_read(&page->_count); +} + +static inline int page_count(struct page *page) +{ + return atomic_read(&compound_head(page)->_count); +} + +static inline void set_page_count(struct page *page, int v) +{ + atomic_set(&page->_count, v); + if (page_ref_tracepoint_active(__tracepoint_page_ref_set)) + __page_ref_set(page, v); +} + +/* + * Setup the page count before being freed into the page allocator for + * the first time (boot or memory hotplug) + */ +static inline void init_page_count(struct page *page) +{ + set_page_count(page, 1); +} + +static inline void page_ref_add(struct page *page, int nr) +{ + atomic_add(nr, &page->_count); + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) + __page_ref_mod(page, nr); +} + +static inline void page_ref_sub(struct page *page, int nr) +{ + atomic_sub(nr, &page->_count); + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) + __page_ref_mod(page, -nr); +} + +static inline void page_ref_inc(struct page *page) +{ + atomic_inc(&page->_count); + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) + __page_ref_mod(page, 1); +} + +static inline void page_ref_dec(struct page *page) +{ + atomic_dec(&page->_count); + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) + __page_ref_mod(page, -1); +} + +static inline int page_ref_sub_and_test(struct page *page, int nr) +{ + int ret = atomic_sub_and_test(nr, &page->_count); + + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_test)) + __page_ref_mod_and_test(page, -nr, ret); + return ret; +} + +static inline int page_ref_dec_and_test(struct page *page) +{ + int ret = atomic_dec_and_test(&page->_count); + + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_test)) + __page_ref_mod_and_test(page, -1, ret); + return ret; +} + +static inline int page_ref_dec_return(struct page *page) +{ + int ret = atomic_dec_return(&page->_count); + + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_return)) + __page_ref_mod_and_return(page, -1, ret); + return ret; +} + +static inline int page_ref_add_unless(struct page *page, int nr, int u) +{ + int ret = atomic_add_unless(&page->_count, nr, u); + + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_unless)) + __page_ref_mod_unless(page, nr, ret); + return ret; +} + +static inline int page_ref_freeze(struct page *page, int count) +{ + int ret = likely(atomic_cmpxchg(&page->_count, count, 0) == count); + + if (page_ref_tracepoint_active(__tracepoint_page_ref_freeze)) + __page_ref_freeze(page, count, ret); + return ret; +} + +static inline void page_ref_unfreeze(struct page *page, int count) +{ + VM_BUG_ON_PAGE(page_count(page) != 0, page); + VM_BUG_ON(count == 0); + + atomic_set(&page->_count, count); + if (page_ref_tracepoint_active(__tracepoint_page_ref_unfreeze)) + __page_ref_unfreeze(page, count); +} + +#endif |