[PATCH] adjust /dev/{kmem,mem,port} write handlers

The /dev/mem and /dev/kmem write handlers weren't fully POSIX compliant in
that they wouldn't always force the file pointer to be updated when
returning success status.

The /dev/port write handler was inconsistent with the /dev/mem and
/dev/kmem handlers in that when encountering a -EFAULT condition after
already having written a number of items it would return -EFAULT rather
than the number of bytes written.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 15 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 29c41f4418c0..26d0116b48d4 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -216,11 +216,9 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
 
                 copied = copy_from_user(ptr, buf, sz);
                 if (copied) {
-                        ssize_t ret;
-
-                        ret = written + (sz - copied);
-                        if (ret)
-                                return ret;
+                        written += sz - copied;
+                        if (written)
+                                break;
                         return -EFAULT;
                 }
                 buf += sz;
@@ -456,11 +454,9 @@ do_write_kmem(void *p, unsigned long realp, const char __user * buf,
 
                 copied = copy_from_user(ptr, buf, sz);
                 if (copied) {
-                        ssize_t ret;
-
-                        ret = written + (sz - copied);
-                        if (ret)
-                                return ret;
+                        written += sz - copied;
+                        if (written)
+                                break;
                         return -EFAULT;
                 }
                 buf += sz;
@@ -514,11 +510,10 @@ static ssize_t write_kmem(struct file * file, const char __user * buf,
                         if (len) {
                                 written = copy_from_user(kbuf, buf, len);
                                 if (written) {
-                                        ssize_t ret;
-
+                                        if (wrote + virtr)
+                                                break;
                                         free_page((unsigned long)kbuf);
-                                        ret = wrote + virtr + (len - written);
-                                        return ret ? ret : -EFAULT;
+                                        return -EFAULT;
                                 }
                         }
                         len = vwrite(kbuf, (char *)p, len);
@@ -563,8 +558,11 @@ static ssize_t write_port(struct file * file, const char __user * buf,
                 return -EFAULT;
         while (count-- > 0 && i < 65536) {
                 char c;
-                if (__get_user(c, tmp)) 
+                if (__get_user(c, tmp)) {
+                        if (tmp > buf)
+                                break;
                         return -EFAULT; 
+                }
                 outb(c,i);
                 i++;
                 tmp++;