[PATCH] timekeeping: check params before use them

[PATCH] timekeeping: check params before use them

[Neil Zhang]

Sometimes we won't need all the information from
get_xtime_and_monotonic_and_sleep_offset(),
so let's check the params before assign the value to them.

Signed-off-by: Neil Zhang <zhangwm@marvell.com>
---
 kernel/time/timekeeping.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0aa4ce8..f0e8f53 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1598,9 +1598,12 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
 
 	do {
 		seq = read_seqcount_begin(&timekeeper_seq);
-		*xtim = tk_xtime(tk);
-		*wtom = tk->wall_to_monotonic;
-		*sleep = tk->total_sleep_time;
+		if (xtim)
+			*xtim = tk_xtime(tk);
+		if (wtom)
+			*wtom = tk->wall_to_monotonic;
+		if (sleep)
+			*sleep = tk->total_sleep_time;
 	} while (read_seqcount_retry(&timekeeper_seq, seq));
 }
 
-- 
1.7.9.5

Re: [PATCH] timekeeping: check params before use them

[John Stultz]

On 03/27/2014 01:12 AM, Neil Zhang wrote:
> Sometimes we won't need all the information from
> get_xtime_and_monotonic_and_sleep_offset(),
> so let's check the params before assign the value to them.

So I think the single in-kernel user of this function does use all of
the information.

Can you expand on how your using this and why the extra conditionals are
worth while?

thanks
-john

RE: [PATCH] timekeeping: check params before use them

[Neil Zhang]

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> -----Original Message-----
> From: John Stultz [mailto:john.stultz@linaro.org]
> Sent: 2014Äê3ÔÂ28ÈÕ 1:26
> To: Neil Zhang; tglx@linutronix.de
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] timekeeping: check params before use them
> 
> On 03/27/2014 01:12 AM, Neil Zhang wrote:
> > Sometimes we won't need all the information from
> > get_xtime_and_monotonic_and_sleep_offset(),
> > so let's check the params before assign the value to them.
> 
> So I think the single in-kernel user of this function does use all of the
> information.
> 
> Can you expand on how your using this and why the extra conditionals are
> worth while?
> 

Please refer to my another patch.
printk: add sleep time into timestamp

I want to add sleep time into printk's timestamp.

> thanks
> -john

Best Regards,
Neil Zhang
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