/dev/mem: introduce size_inside_page()

[karo-tx-linux.git] / drivers / char / mem.c

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index a074fceb67d30109c08e862b9b775b6c058da904..1ffb6dd3eae4201705656edac515288d3ff411a0 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -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) {