linux-kernel - Re: [PATCH] kdb: Change timespec to use timespec64

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Date:   Thu, 25 Jan 2018 11:38:08 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Jason Wessel <jason.wessel@...driver.com>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        kgdb-bugreport@...ts.sourceforge.net,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kdb: Change timespec to use timespec64

On Thu, Jan 25, 2018 at 05:18:54PM +0800, Baolin Wang wrote:
> On 25 January 2018 at 16:55, Arnd Bergmann <arnd@...db.de> wrote:
> > On Thu, Jan 25, 2018 at 9:05 AM, Baolin Wang <baolin.wang@...aro.org> wrote:
> >> @@ -2554,7 +2554,7 @@ static int kdb_summary(int argc, const char **argv)
> >>         kdb_printf("domainname %s\n", init_uts_ns.name.domainname);
> >>         kdb_printf("ccversion  %s\n", __stringify(CCVERSION));
> >>
> >> -       now = __current_kernel_time();
> >> +       now = current_kernel_time64();
> >>         kdb_gmtime(&now, &tm);
> >>         kdb_printf("date       %04d-%02d-%02d %02d:%02d:%02d "
> >>                    "tz_minuteswest %d\n",
> >
> > Thanks for picking this one up again, we should find a permanent solution here.
> > Unfortunately you patch is incorrect, as we cannot safely call
> > current_kernel_time64()
> > from NMI context.
> 
> Ah, thanks for pointing out the issue, since I do not know what
> context the function will be called in kdb.
> 
> >
> > The __ prefix on __current_kernel_time() indicates that this is a special call
> > that intentionally doesn't read the hardware time to avoid taking locks that
> > might already be held in the context from which we entered the debugger.
> >
> > See https://patchwork.kernel.org/patch/10002097/ for my earlier patch.
> 
> This patch had not been merged into mainline?

Not yet (and I'm afraid it's not in kgdb-next either) but the ack from Jason is from 
this kernel cycle so we'll see what can be done!


Daniel.