[Crash-utility] Crash-utility Digest, Vol 179, Issue 4

[HAGIO KAZUHITO(萩尾 一仁)]

Hi Lianbo,

> -----Original Message-----
> 在 2020年08月07日 00:00, crash-utility-request at redhat.com 写道:
> > Message: 5
> > Date: Thu,  6 Aug 2020 09:30:22 -0400
> > From: Dave Wysochanski <dwysocha at redhat.com>
> > To: crash-utility at redhat.com
> > Subject: [Crash-utility] [PATCH v3] Fix "log" command when crash is
> > 	started	with "--minimal" option
> > Message-ID: <20200806133022.2127538-1-dwysocha at redhat.com>
> >
> > 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.
> >
> Hi, Dave Wysochanski
> 
> Thank you for the patch.
> 
> > 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>
> > ---
> >  kernel.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel.c b/kernel.c
> > index 5ed6021..95119f3 100644
> > --- a/kernel.c
> > +++ b/kernel.c
> > @@ -4939,7 +4939,10 @@ cmd_log(void)
> >          if (argerrs)
> >                  cmd_usage(pc->curcmd, SYNOPSIS);
> >
> > -	if (kt->boot_date.tv_sec == 0) {
> > +	if (msg_flags & SHOW_LOG_CTIME && pc->flags & MINIMAL_MODE)
> > +		error(FATAL, "log: option 'T' not available in minimal mode\n");
> > +
> > +	if (msg_flags & SHOW_LOG_CTIME && kt->boot_date.tv_sec == 0) {
> 
> The above two 'if' statements have the same checking condition, would you mind putting them together
> as a statement block? E.g:
> 
> +       if (msg_flags & SHOW_LOG_CTIME) {
> +               if (pc->flags & MINIMAL_MODE) {
> +                       error(WARNING, "the option '-T' not available in minimal mode\n");
> +                       return;
> +               }
> +
> +               if (kt->boot_date.tv_sec == 0) {
> ...
> +               }
>         }
> 
> In addition, might it be more reasonable to issue a warning instead of a fatal error?

hmm, why do you think so?  I think FATAL is fine because we cannot proceed
anymore and there is no memory to be released.

Thanks,
Kazu

> 
> Thanks.
> Lianbo
> 
> >  		ulonglong uptime_jiffies;
> >  		ulong  uptime_sec;
> >  		get_uptime(NULL, &uptime_jiffies);
> > -- 2.27.0
> 
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