[PATCH] RTC: rtc-dev tweak for 64-bit kernel

Make rtc-dev work well on 64-bit platforms with 32-bit userland.  On those
platforms, users might try to read 32-bit integer value.  This patch make
rtc-dev's read() work well for both "int" and "long" size.  This tweak is came
from genrtc driver.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index b1e3e6179e569f81d207b286bc4ec290195ff330..6c9ad92747fddd2c35061c5e49a4bcc1ad04e2cd 100644 (file)
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -58,7 +58,7 @@ rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
        unsigned long data;
        ssize_t ret;
 
-       if (count < sizeof(unsigned long))
+       if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
                return -EINVAL;
 
        add_wait_queue(&rtc->irq_queue, &wait);
@@ -90,11 +90,16 @@ rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
        if (ret == 0) {
                /* Check for any data updates */
                if (rtc->ops->read_callback)
-                       data = rtc->ops->read_callback(rtc->class_dev.dev, data);
-
-               ret = put_user(data, (unsigned long __user *)buf);
-               if (ret == 0)
-                       ret = sizeof(unsigned long);
+                       data = rtc->ops->read_callback(rtc->class_dev.dev,
+                                                      data);
+
+               if (sizeof(int) != sizeof(long) &&
+                   count == sizeof(unsigned int))
+                       ret = put_user(data, (unsigned int __user *)buf) ?:
+                               sizeof(unsigned int);
+               else
+                       ret = put_user(data, (unsigned long __user *)buf) ?:
+                               sizeof(unsigned long);
        }
        return ret;
 }