Introduce size_inside_page() to replace duplicate /dev/mem code. Also apply it to /dev/kmem, whose alignment logic was buggy. CC: Marcelo Tosatti CC: Greg Kroah-Hartman CC: Mark Brown CC: Johannes Berg CC: Avi Kivity Signed-off-by: Wu Fengguang --- drivers/char/mem.c | 60 +++++++++++++------------------------------ 1 file changed, 19 insertions(+), 41 deletions(-) --- linux.orig/drivers/char/mem.c +++ linux/drivers/char/mem.c @@ -35,6 +35,19 @@ # include #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. @@ -142,15 +155,7 @@ static ssize_t read_mem(struct file * fi #endif while (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, count); + sz = size_inside_page(p, count); if (!range_is_allowed(p >> PAGE_SHIFT, count)) return -EPERM; @@ -209,15 +214,7 @@ static ssize_t write_mem(struct file * f #endif while (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, count); + sz = size_inside_page(p, count); if (!range_is_allowed(p >> PAGE_SHIFT, sz)) return -EPERM; @@ -430,15 +427,7 @@ static ssize_t read_kmem(struct file *fi } #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 +451,8 @@ static ssize_t read_kmem(struct file *fi 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 +497,8 @@ do_write_kmem(void *p, unsigned long rea 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 +558,8 @@ static ssize_t write_kmem(struct file * 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; written = copy_from_user(kbuf, buf, len); if (written) { if (wrote + virtr) -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/