Re: [PATCH] genrtc: fix read on 64-bit platforms

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

On Fri, 28 Apr 2006 23:34:21 -0700, Andrew Morton <akpm@osdl.org> wrote:
> > Fix genrtc's read() routine for 64-bit platforms.
> 
> When fixing something, please provide a description of what the problem was
> and also a description of how the patch fixes it (unless it's obvious, of
> course).

Thanks.  Here is a same patch with an updated description.


Fix genrtc's read() routine for 64-bit platforms.  Current
gen_rtc_read() stores 64bit integer and returns 8 even if an user
tried to read a 32bit integer.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

diff --git a/drivers/char/genrtc.c b/drivers/char/genrtc.c
index d3a2bc3..588fca5 100644
--- a/drivers/char/genrtc.c
+++ b/drivers/char/genrtc.c
@@ -200,13 +200,13 @@ static ssize_t gen_rtc_read(struct file 
 	/* first test allows optimizer to nuke this case for 32-bit machines */
 	if (sizeof (int) != sizeof (long) && count == sizeof (unsigned int)) {
 		unsigned int uidata = data;
-		retval = put_user(uidata, (unsigned long __user *)buf);
+		retval = put_user(uidata, (unsigned int __user *)buf) ?:
+			sizeof(unsigned int);
 	}
 	else {
-		retval = put_user(data, (unsigned long __user *)buf);
+		retval = put_user(data, (unsigned long __user *)buf) ?:
+			sizeof(unsigned long);
 	}
-	if (!retval)
-		retval = sizeof(unsigned long);
  out:
 	current->state = TASK_RUNNING;
 	remove_wait_queue(&gen_rtc_wait, &wait);