/dev/mem: make size_inside_page() logic straight

Also convert more size_inside_page() users.

Signed-off-by: Wu 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index c6b2fbc..192af59 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -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;