Re: BUG in check_monotonic_clock()

[George Anzinger <george@wildturkeyranch.net>]

Daniel Walker wrote:
> This is off a dual P3 during boot with 2.6.15-rt6. I'll send the .config
> privately . I had a fair amount of debugging on.

Has the attached patch been applied?  Fixed this for me....

George
--
> check_monotonic_clock: monotonic inconsistency detected!
>         from        1a27e7384 (7021163396) to        19f92d748 (6972168008).
> udev/238[CPU#1]: BUG in check_monotonic_clock at kernel/time/timeofday.c:160
>  [<c0105b03>] dump_stack+0x23/0x30 (20)
>  [<c0129e43>] __WARN_ON+0x63/0x80 (40)
>  [<c0148584>] check_monotonic_clock+0xd4/0xe0 (52)
>  [<c01489b8>] get_monotonic_clock+0xc8/0x100 (56)
>  [<c014475d>] __hrtimer_start+0xdd/0x100 (40)
>  [<c0400046>] schedule_hrtimer+0x46/0xd0 (48)
>  [<c0144f0f>] hrtimer_nanosleep+0x5f/0x130 (104)
>  [<c0145053>] sys_nanosleep+0x73/0x80 (36)
>  [<c0104b2a>] syscall_call+0x7/0xb (-4020)
> ---------------------------
> | preempt count: 00000002 ]
> | 2-level deep critical section nesting:
> ----------------------------------------
> .. [<c014cf1c>] .... add_preempt_count+0x1c/0x20
> .....[<c0143e2a>] ..   ( <= lock_hrtimer_base+0x2a/0x60)
> .. [<c014cf1c>] .... add_preempt_count+0x1c/0x20
> .....[<c0129df6>] ..   ( <= __WARN_ON+0x16/0x80)
>
>
> -
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--
George Anzinger   george@wildturkeyranch.net
HRT (High-res-timers):  http://sourceforge.net/projects/high-res-timers/

 kernel/time.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

Index: linux-2.6.16-rc/kernel/time.c
===================================================================
--- linux-2.6.16-rc.orig/kernel/time.c
+++ linux-2.6.16-rc/kernel/time.c
@@ -702,16 +702,19 @@ void set_normalized_timespec(struct time
  *
  * Returns the timespec representation of the nsec parameter.
  */
-inline struct timespec ns_to_timespec(const nsec_t nsec)
+struct timespec ns_to_timespec(const nsec_t nsec)
 {
 	struct timespec ts;
 
-	if (nsec)
+	if (!nsec) return (struct timespec){0, 0};
+
+	if (nsec < 0) {
+		ts.tv_sec = div_long_long_rem_signed(-nsec, NSEC_PER_SEC,
+						     &ts.tv_nsec);
+		set_normalized_timespec(&ts, -ts.tv_sec, -ts.tv_nsec);
+	} else
 		ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC,
 						     &ts.tv_nsec);
-	else
-		ts.tv_sec = ts.tv_nsec = 0;
-
 	return ts;
 }