Subject: Re: linux-next: build failure after merge of the final tree (driver-core tree related)

From: Kay Sievers <[email-masked]>
Date: Tue, 08 May 2012 13:04:17 +0200

On Tue, 2012-05-08 at 18:02 +1000, Stephen Rothwell wrote:
> After merging the final tree, today's linux-next build (powerpc
> allnoconfig) failed like this:
> 
> kernel/built-in.o: In function `devkmsg_read':
> printk.c:(.text+0x27e8): undefined reference to `__udivdi3'

Oops, let's use do_div().

Thanks,
Kay

From: Kay Sievers <[email-masked]>
Subject: kmsg: use do_div() to divide 64bit integer

On Tue, May 8, 2012 at 10:02 AM, Stephen Rothwell <[email-masked]> wrote:
> kernel/built-in.o: In function `devkmsg_read':
> printk.c:(.text+0x27e8): undefined reference to `__udivdi3'
> Most probably the "msg->ts_nsec / 1000" since
> ts_nsec is a u64 and this is a 32 bit build ...

Signed-off-by: Kay Sievers <[email-masked]>
---
 kernel/printk.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -407,6 +407,7 @@ static ssize_t devkmsg_read(struct file
 {
 	struct devkmsg_user *user = file->private_data;
 	struct log *msg;
+	u64 ts_usec;
 	size_t i;
 	size_t len;
 	ssize_t ret;
@@ -441,8 +442,10 @@ static ssize_t devkmsg_read(struct file
 	}
 
 	msg = log_from_idx(user->idx);
+	ts_usec = msg->ts_nsec;
+	do_div(ts_usec, 1000);
 	len = sprintf(user->buf, "%u,%llu,%llu;",
-		      msg->level, user->seq, msg->ts_nsec / 1000);
+		      msg->level, user->seq, ts_usec);
 
 	/* escape non-printable characters */
 	for (i = 0; i < msg->text_len; i++) {