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Date: Mon, 29 Feb 2016 18:55:24 -0800 From: Guenter Roeck <linux@...ck-us.net> To: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>, Andrew Morton <akpm@...ux-foundation.org>, Thomas Mingarelli <thomas.mingarelli@....com>, Wim Van Sebroeck <wim@...ana.be>, Corey Minyard <minyard@....org> Cc: linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...nel.org>, Borislav Petkov <bp@...en8.de>, openipmi-developer@...ts.sourceforge.net Subject: Re: [PATCH 3/3] hpwdt: Use nmi_panic() when kernel panics in NMI handler On 02/29/2016 05:50 PM, Hidehiro Kawai wrote: > commit 58c5661f2144 ("panic, x86: Allow CPUs to save registers even > if looping in NMI context") introduced nmi_panic() which prevents > concurrent/recursive execution of panic(). It also saves registers > for the crash dump on x86. > > hpwdt driver can call panic() from NMI handler, so replace it with > nmi_panic(). > > Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com> > Cc: Thomas Mingarelli <thomas.mingarelli@....com> > Cc: Wim Van Sebroeck <wim@...ana.be> > Cc: Guenter Roeck <linux@...ck-us.net> > Cc: linux-watchdog@...r.kernel.org > --- > drivers/watchdog/hpwdt.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c > index 92443c3..fd0486f 100644 > --- a/drivers/watchdog/hpwdt.c > +++ b/drivers/watchdog/hpwdt.c > @@ -496,11 +496,12 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs) > > if (!is_icru && !is_uefi) { > if (cmn_regs.u1.ral == 0) { > - panic("An NMI occurred, " > + nmi_panic(regs, "An NMI occurred, " > "but unable to determine source.\n"); This message should really be in a single line. Sure, strictly speaking that should be done in a separate patch, but since you touch the line you might as well fix it. > + goto handled; The goto is unnecessary. Just return NMI_HANDLED. > } > } > - panic("An NMI occurred. Depending on your system the reason " > + nmi_panic(regs, "An NMI occurred. Depending on your system the reason " > "for the NMI is logged in any one of the following " > "resources:\n" > "1. Integrated Management Log (IML)\n" > @@ -508,6 +509,13 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs) > "3. OA Forward Progress Log\n" > "4. iLO Event Log"); > > +handled: > + /* > + * Returning from nmi_panic() means this CPU was processing panic() > + * before NMI. Return NMI_HANDLED and go back to panic routines. > + */ I don't think this comment adds much if any value. > + return NMI_HANDLED; > + > out: Any goto to this label does no longer serve a useful purpose (if it ever served one), and should be replaced with "return NMI_DONE;" > return NMI_DONE; > } > > >
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