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mm: rename _count, field of the struct page, to _refcount

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Many developers already know that field for reference count of the
struct page is _count and atomic type.  They would try to handle it
directly and this could break the purpose of page reference count
tracepoint.  To prevent direct _count modification, this patch rename it
to _refcount and add warning message on the code.  After that, developer
who need to handle reference count will find that field should not be
accessed directly.

[akpm@linux-foundation.org: fix comments, per Vlastimil]
[akpm@linux-foundation.org: Documentation/vm/transhuge.txt too]
[sfr@canb.auug.org.au: sync ethernet driver changes]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Sunil Goutham <sgoutham@cavium.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Manish Chopra <manish.chopra@qlogic.com>
Cc: Yuval Mintz <yuval.mintz@qlogic.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joonsoo Kim
2016-05-19 17:10:49 -07:00
committed by Linus Torvalds
parent 6d061f9f61
commit 0139aa7b7f
17 changed files with 58 additions and 54 deletions
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26
include/linux/page_ref.h
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@@ -63,17 +63,17 @@ static inline void __page_ref_unfreeze(struct page *page, int v)
static inline int page_ref_count(struct page *page)
{
return atomic_read(&page->_count);
return atomic_read(&page->_refcount);
}
static inline int page_count(struct page *page)
{
return atomic_read(&compound_head(page)->_count);
return atomic_read(&compound_head(page)->_refcount);
}
static inline void set_page_count(struct page *page, int v)
{
atomic_set(&page->_count, v);
atomic_set(&page->_refcount, v);
if (page_ref_tracepoint_active(__tracepoint_page_ref_set))
__page_ref_set(page, v);
}
@@ -89,35 +89,35 @@ static inline void init_page_count(struct page *page)
static inline void page_ref_add(struct page *page, int nr)
{
atomic_add(nr, &page->_count);
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->_count);
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->_count);
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->_count);
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->_count);
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);
@@ -126,7 +126,7 @@ static inline int page_ref_sub_and_test(struct page *page, int nr)
static inline int page_ref_dec_and_test(struct page *page)
{
int ret = atomic_dec_and_test(&page->_count);
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);
@@ -135,7 +135,7 @@ static inline int page_ref_dec_and_test(struct page *page)
static inline int page_ref_dec_return(struct page *page)
{
int ret = atomic_dec_return(&page->_count);
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);
@@ -144,7 +144,7 @@ static inline int page_ref_dec_return(struct page *page)
static inline int page_ref_add_unless(struct page *page, int nr, int u)
{
int ret = atomic_add_unless(&page->_count, nr, 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);
@@ -153,7 +153,7 @@ static inline int page_ref_add_unless(struct page *page, int nr, int u)
static inline int page_ref_freeze(struct page *page, int count)
{
int ret = likely(atomic_cmpxchg(&page->_count, count, 0) == 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);
@@ -165,7 +165,7 @@ 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);
atomic_set(&page->_refcount, count);
if (page_ref_tracepoint_active(__tracepoint_page_ref_unfreeze))
__page_ref_unfreeze(page, count);
}