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/dev/mem: introduce size_inside_page()

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commit f222318e9c upstream

/dev/mem: introduce size_inside_page()

[ cebbert@redhat.com : backport to 2.6.32 ]
[ subset of original patch, for just /dev/kmem ]

Introduce size_inside_page() to replace duplicate /dev/mem code.

Also apply it to /dev/kmem, whose alignment logic was buggy.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Wu Fengguang
2010-02-05 15:00:52 -05:00
committed by Greg Kroah-Hartman
parent 06eeea406c
commit 0e1104ada3
1 changed files with 17 additions and 23 deletions
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40
drivers/char/mem.c
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@@ -35,6 +35,19 @@
# include <linux/efi.h>
#endif
static inline unsigned long size_inside_page(unsigned long start,
unsigned long size)
{
unsigned long sz;
if (-start & (PAGE_SIZE - 1))
sz = -start & (PAGE_SIZE - 1);
else
sz = PAGE_SIZE;
return min_t(unsigned long, sz, size);
}
/*
* Architectures vary in how they handle caching for addresses
* outside of main memory.
@@ -430,15 +443,7 @@ static ssize_t read_kmem(struct file *file, char __user *buf,
}
#endif
while (low_count > 0) {
/*
* Handle first page in case it's not aligned
*/
if (-p & (PAGE_SIZE - 1))
sz = -p & (PAGE_SIZE - 1);
else
sz = PAGE_SIZE;
sz = min_t(unsigned long, sz, low_count);
sz = size_inside_page(p, low_count);
/*
* On ia64 if a page has been mapped somewhere as
@@ -462,10 +467,8 @@ static ssize_t read_kmem(struct file *file, char __user *buf,
if (!kbuf)
return -ENOMEM;
while (count > 0) {
int len = count;
int len = size_inside_page(p, count);
if (len > PAGE_SIZE)
len = PAGE_SIZE;
len = vread(kbuf, (char *)p, len);
if (!len)
break;
@@ -510,15 +513,8 @@ do_write_kmem(void *p, unsigned long realp, const char __user * buf,
while (count > 0) {
char *ptr;
/*
* Handle first page in case it's not aligned
*/
if (-realp & (PAGE_SIZE - 1))
sz = -realp & (PAGE_SIZE - 1);
else
sz = PAGE_SIZE;
sz = min_t(unsigned long, sz, count);
sz = size_inside_page(realp, count);
/*
* On ia64 if a page has been mapped somewhere as
@@ -578,10 +574,8 @@ static ssize_t write_kmem(struct file * file, const char __user * buf,
if (!kbuf)
return wrote ? wrote : -ENOMEM;
while (count > 0) {
int len = count;
int len = size_inside_page(p, count);
if (len > PAGE_SIZE)
len = PAGE_SIZE;
if (len) {
written = copy_from_user(kbuf, buf, len);
if (written) {