linux-kernel - Re: [PATCH] kdb: use ktime_get_seconds() instead of ktime_get

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Message-ID: <4c5edb5b-8d48-3fb3-2068-2493df228ed2@windriver.com>
Date:   Thu, 25 Jan 2018 21:31:59 -0600
From:   Jason Wessel <jason.wessel@...driver.com>
To:     Baolin Wang <baolin.wang@...aro.org>, <daniel.thompson@...aro.org>
CC:     <mingo@...nel.org>, <arnd@...db.de>, <broonie@...nel.org>,
        <kgdb-bugreport@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kdb: use ktime_get_seconds() instead of ktime_get_ts()

On 01/25/2018 09:03 PM, Baolin Wang wrote:
> The kdb code will print the monotonic time by ktime_get_ts(), but
> the ktime_get_ts() will be protected by a sequence lock, that will
> introduce one deadlock risk if the lock was already held in the
> context from which we entered the debugger.
>
> Since kdb is only interested in the second field, we can use the
> ktime_get_seconds() to get the monotonic time without a lock,
> moreover we can remove the 'struct timespec', which is not y2038
> safe.
>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>

Acked-by: Jason Wessel <jason.wessel@...driver.com>


Thanks.   Added to the kgdb-next branch for the next merge cycle.

Jason.

> ---
>   kernel/debug/kdb/kdb_main.c |    4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> index 69e70f4..f0fc6f7 100644
> --- a/kernel/debug/kdb/kdb_main.c
> +++ b/kernel/debug/kdb/kdb_main.c
> @@ -2486,10 +2486,8 @@ static int kdb_kill(int argc, const char **argv)
>    */
>   static void kdb_sysinfo(struct sysinfo *val)
>   {
> -	struct timespec uptime;
> -	ktime_get_ts(&uptime);
>   	memset(val, 0, sizeof(*val));
> -	val->uptime = uptime.tv_sec;
> +	val->uptime = ktime_get_seconds();
>   	val->loads[0] = avenrun[0];
>   	val->loads[1] = avenrun[1];
>   	val->loads[2] = avenrun[2];