On 2014.09.14 at 11:13 +0200, Geert Uytterhoeven wrote:
> On Sun, Sep 14, 2014 at 7:54 AM, Markus Trippelsdorf
> <mar...@trippelsdorf.de> wrote:
> > On 2014.09.14 at 07:09 +0200, Markus Trippelsdorf wrote:
> >> Just noticed this today:
> >>
> >> Sep 14 06:51:57 x4 kernel: [sched_delayed] ^a4CE: hpet increased
> >> min_delta_ns to 20115 nsec
> >>
> >> in hex:
> >> 20 01 34 43 45 3A 20
> >>
> >> Must be a recent regression.
> >
> > It looks like a combination of commit 504d58745c9ca and commit
> > 458df9fd4815b causes the issue.
> > 458df9fd4815b changed the loglevel of printk_deferred to a hardcoded
> > KERN_WARNING. And 504d58745c9ca changed the printk in
> > kernel/time/clockevents.c to printk_deferred.
> > But now the KERN_WARNING loglevel of printk_deferred in
> > kernel/time/clockevents.c is redundant and responsible for the weird
> > 01 34 character combination (KERN_SOH "4").
>
> vprintk_emit() has:
>
> if (in_sched)
> text_len = scnprintf(text, sizeof(textbuf),
> KERN_WARNING "[sched_delayed] ");
>
> text_len += vscnprintf(text + text_len,
> sizeof(textbuf) - text_len, fmt, args);
>
> Hence if in_sched, "[sched_delayed] " is inserted before the printed
> message. As most printed messages have a KERN_* prefix, this
> prefix now ends up in the middle of the message, causing the issue.
>
> A simple solution is to print a newline after the "[sched_delayed]", but
> this will break the line.
>
> Better, but more complicated, would be to remove the KERN_* prefix
> (if it exists) from the next message if in_sched is set.
Or just get rid of the "[sched_delayed] " thing. Does it really convey
useful information to the user?
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 1ce770687ea8..b13c8650a751 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1680,12 +1680,8 @@ asmlinkage int vprintk_emit(int facility, int level,
* The printf needs to come first; we need the syslog
* prefix which might be passed-in as a parameter.
*/
- if (in_sched)
- text_len = scnprintf(text, sizeof(textbuf),
- KERN_WARNING "[sched_delayed] ");
- text_len += vscnprintf(text + text_len,
- sizeof(textbuf) - text_len, fmt, args);
+ text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
/* mark and strip a trailing newline */
if (text_len && text[text_len-1] == '\n') {
--
Markus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
