[RESEND][PATCH] Fix oops on !GENERIC_TIME systems when accessing current_clocksource

[john stultz]

No one has replied to this, so I wanted to send it out again.

Aaro Koskinen reported an issue in bug #15366, where on non-GENERIC_TIME
systems,
accessing /sys/devices/system/clocksource/clocksource0/current_clocksource would oops the system.

It seems the timekeeper/clocksource rework missed initializing the
curr_clocksource value in the !GENERIC_TIME.

The following patch makes sure it gets initialized, and avoids the
issue.

Thanks to Aaro for reporting and diagnosing the issue as well as testing
the fix!

Bug Details: http://bugzilla.kernel.org/show_bug.cgi?id=15366

Too late for 2.6.33, but this likely should go into 2.6.33-stable and
2.6.32-stable.

thanks
-john

Signed-off-by: John Stultz <john...@us.ibm.com>

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index e85c234..c436ee5 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -568,6 +568,10 @@ static inline void clocksource_select(void) { }
*/
static int __init clocksource_done_booting(void)
{
+ mutex_lock(&clocksource_mutex);
+ curr_clocksource = clocksource_default_clock();
+ mutex_unlock(&clocksource_mutex);
+
finished_booting = 1;

/*

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[tip-bot for john stultz]

Commit-ID: ad6759fbf35d104dbf573cd6f4c6784ad6823f7e
Gitweb: http://git.kernel.org/tip/ad6759fbf35d104dbf573cd6f4c6784ad6823f7e
Author: john stultz <john...@us.ibm.com>
AuthorDate: Mon, 1 Mar 2010 12:34:43 -0800
Committer: Thomas Gleixner <tg...@linutronix.de>
CommitDate: Tue, 2 Mar 2010 09:22:25 +0100

timekeeping: Prevent oops when GENERIC_TIME=n

Aaro Koskinen reported an issue in kernel.org bugzilla #15366, where

on non-GENERIC_TIME systems, accessing
/sys/devices/system/clocksource/clocksource0/current_clocksource

results in an oops.

It seems the timekeeper/clocksource rework missed initializing the

curr_clocksource value in the !GENERIC_TIME case.

Thanks to Aaro for reporting and diagnosing the issue as well as
testing the fix!

Reported-by: Aaro Koskinen <aaro.k...@iki.fi>
Signed-off-by: John Stultz <john...@us.ibm.com>
Cc: Martin Schwidefsky <schwi...@de.ibm.com>
Cc: sta...@kernel.org
LKML-Reference: <1267475683.4...@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tg...@linutronix.de>

---
kernel/time/clocksource.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 1f663d2..1f5dde6 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -592,6 +592,10 @@ static inline void clocksource_select(void) { }

[john stultz]

On Mon, 2010-03-01 at 12:34 -0800, john stultz wrote:
> No one has replied to this, so I wanted to send it out again.

Just another ping here. I know the patch has made it to -tip, but its
something that should be needed for 2.6.34, 2.6.33-stable.

thanks
-john

[Thomas Gleixner]

On Mon, 8 Mar 2010, john stultz wrote:

> On Mon, 2010-03-01 at 12:34 -0800, john stultz wrote:
> > No one has replied to this, so I wanted to send it out again.
>
> Just another ping here. I know the patch has made it to -tip, but its
> something that should be needed for 2.6.34, 2.6.33-stable.

I'm going to send a pull request tomorrow.

Thanks,

tglx