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Commit 7fabaddd authored by Wu Fengguang's avatar Wu Fengguang Committed by Linus Torvalds
Browse files

/dev/mem: make size_inside_page() logic straight 



Also convert more size_inside_page() users.

Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Avi Kivity <avi@qumranet.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fa29e97b

drivers/char/mem.c

+12 −22
Original line number Diff line number Diff line
@@ -39,12 +39,9 @@ static inline unsigned long size_inside_page(unsigned long start, 
{

	unsigned long sz;



	if (-start & (PAGE_SIZE - 1))

		sz = -start & (PAGE_SIZE - 1);

	else

		sz = PAGE_SIZE;

	sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));



	return min_t(unsigned long, sz, size);

	return min(sz, size);

}



/*
@@ -139,9 +136,7 @@ static ssize_t read_mem(struct file * file, char __user * buf, 
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED

	/* we don't have page 0 mapped on sparc and m68k.. */

	if (p < PAGE_SIZE) {

		sz = PAGE_SIZE - p;

		if (sz > count) 

			sz = count; 

		sz = size_inside_page(p, count);

		if (sz > 0) {

			if (clear_user(buf, sz))

				return -EFAULT;
@@ -201,9 +196,7 @@ static ssize_t write_mem(struct file * file, const char __user * buf, 
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED

	/* we don't have page 0 mapped on sparc and m68k.. */

	if (p < PAGE_SIZE) {

		unsigned long sz = PAGE_SIZE - p;

		if (sz > count)

			sz = count;

		sz = size_inside_page(p, count);

		/* Hmm. Do something? */

		buf += sz;

		p += sz;
@@ -412,15 +405,14 @@ static ssize_t read_kmem(struct file *file, char __user *buf, 
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED

		/* we don't have page 0 mapped on sparc and m68k.. */

		if (p < PAGE_SIZE && low_count > 0) {

			size_t tmp = PAGE_SIZE - p;

			if (tmp > low_count) tmp = low_count;

			if (clear_user(buf, tmp))

			sz = size_inside_page(p, low_count);

			if (clear_user(buf, sz))

				return -EFAULT;

			buf += tmp;

			p += tmp;

			read += tmp;

			low_count -= tmp;

			count -= tmp;

			buf += sz;

			p += sz;

			read += sz;

			low_count -= sz;

			count -= sz;

		}

#endif

		while (low_count > 0) {
@@ -480,9 +472,7 @@ do_write_kmem(void *p, unsigned long realp, const char __user * buf, 
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED

	/* we don't have page 0 mapped on sparc and m68k.. */

	if (realp < PAGE_SIZE) {

		unsigned long sz = PAGE_SIZE - realp;

		if (sz > count)

			sz = count;

		sz = size_inside_page(realp, count);

		/* Hmm. Do something? */

		buf += sz;

		p += sz;