[Crash-utility] [PATCH v4] Fix "log" command when crash is started with "--minimal" option

[HAGIO KAZUHITO(萩尾 一仁)]

> -----Original Message-----
> From: crash-utility-bounces at redhat.com <crash-utility-bounces at redhat.com> On Behalf Of Dave Wysochanski
> Sent: Monday, August 17, 2020 4:20 AM
> To: crash-utility at redhat.com
> Subject: [Crash-utility] [PATCH v4] Fix "log" command when crash is started with "--minimal" option
> 
> Commit c86250bce29f introduced the useful '-T' option to print the
> log timestamp in human-readable form.  However, this option does
> not work when crash is invoked with '--minimal' mode, and if tried,
> crash will spin at 100% and continuously crash at a divide by 0
> because machdep->hz == 0.
> 
> Fix this by disallowing this option in minimal mode.  In addition,
> only calculate the logic to calculate kt->boot_date.tv_sec
> when this option is enabled.
> 
> Fixes: c86250bce29f ("Introduction of the "log -T" option...")
> Signed-off-by: Dave Wysochanski <dwysocha at redhat.com>
> Reviewed-by: Wang Long <w at laoqinren.net>
> Tested-by: Mathias Krause <minipli at grsecurity.net>
> Reviewed-by: Lianbo Jiang <lijiang at redhat.com>
> ---
>  kernel.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel.c b/kernel.c
> index 5ed6021..9aa1d4d 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -4939,13 +4939,20 @@ cmd_log(void)
>          if (argerrs)
>                  cmd_usage(pc->curcmd, SYNOPSIS);
> 
> -	if (kt->boot_date.tv_sec == 0) {
> -		ulonglong uptime_jiffies;
> -		ulong  uptime_sec;
> -		get_uptime(NULL, &uptime_jiffies);
> -		uptime_sec = (uptime_jiffies)/(ulonglong)machdep->hz;
> -		kt->boot_date.tv_sec = kt->date.tv_sec - uptime_sec;
> -		kt->boot_date.tv_nsec = 0;
> +	if (msg_flags & SHOW_LOG_CTIME) {
> +		if (pc->flags & MINIMAL_MODE) {
> +			error(WARNING, "log: option 'T' not available in minimal mode\n");
                                       ^^^^^
This extra "log: " is not needed:

crash> log -T
log: WARNING: log: option 'T' not available in minimal mode

Lianbo, would you remove it when applying?  Otherwise,

Acked-by: Kazuhito Hagio <k-hagio-ab at nec.com>

Thanks,
Kazu


> +			return;
> +		}
> +
> +		if (kt->boot_date.tv_sec == 0) {
> +			ulonglong uptime_jiffies;
> +			ulong  uptime_sec;
> +			get_uptime(NULL, &uptime_jiffies);
> +			uptime_sec = (uptime_jiffies)/(ulonglong)machdep->hz;
> +			kt->boot_date.tv_sec = kt->date.tv_sec - uptime_sec;
> +			kt->boot_date.tv_nsec = 0;
> +		}
>  	}
> 
>  	if (msg_flags & SHOW_LOG_AUDIT) {
> --
> 2.27.0
> 
> --
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