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/* SPDX-License-Identifier: GPL-2.0 */
#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->_refcount);
}
static inline int page_count(struct page *page)
{
return atomic_read(&compound_head(page)->_refcount);
}
static inline void set_page_count(struct page *page, int v)
{
atomic_set(&page->_refcount, 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->_refcount);
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->_refcount);
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->_refcount);
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->_refcount);
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->_refcount);
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_inc_return(struct page *page)
{
int ret = atomic_inc_return(&page->_refcount);
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_dec_and_test(struct page *page)
{
int ret = atomic_dec_and_test(&page->_refcount);
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->_refcount);
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->_refcount, 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->_refcount, 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_release(&page->_refcount, count);
if (page_ref_tracepoint_active(__tracepoint_page_ref_unfreeze))
__page_ref_unfreeze(page, count);
}
#endif
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