| Message ID | 1606097320-56762-2-git-send-email-jerry.hoemann@hpe.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | watchdog/hpwdt: Disable Pretimeout/NMI in Crash Path | expand |
On Sun, Nov 22, 2020 at 07:08:39PM -0700, Jerry Hoemann wrote: > NMIs received during the crash path are problematic as hpwdt_pretimeout > handling of the NMI would cause a reentry into kdump. > > The situation is complicated in that I/O errors can be signaled as NMI > circumventing hpwdt_pretimeout's attempt to not claim NMI not associated > with either the WDT or the iLO NMI switch. These NMI can additionally > cause a secondary NMI which cause the system to hang. > > By disabling pretimeout and hpwdtimeout in crash path we both reduce > the risk of receiving an NMI and simuletaneously leave the WDT running > (if it was already in use) to allow the WDT to break the system out of > hangs by the WDT reset. > > Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > drivers/watchdog/hpwdt.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c > index 7d34bcf..eeb4df2 100644 > --- a/drivers/watchdog/hpwdt.c > +++ b/drivers/watchdog/hpwdt.c > @@ -21,6 +21,7 @@ > #include <linux/types.h> > #include <linux/watchdog.h> > #include <asm/nmi.h> > +#include <linux/crash_dump.h> > > #define HPWDT_VERSION "2.0.3" > #define SECS_TO_TICKS(secs) ((secs) * 1000 / 128) > @@ -334,6 +335,11 @@ static int hpwdt_init_one(struct pci_dev *dev, > watchdog_set_nowayout(&hpwdt_dev, nowayout); > watchdog_init_timeout(&hpwdt_dev, soft_margin, NULL); > > + if (is_kdump_kernel()) { > + pretimeout = 0; > + kdumptimeout = 0; > + } > + > if (pretimeout && hpwdt_dev.timeout <= PRETIMEOUT_SEC) { > dev_warn(&dev->dev, "timeout <= pretimeout. Setting pretimeout to zero\n"); > pretimeout = 0; > -- > 1.8.3.1 >
diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c index 7d34bcf..eeb4df2 100644 --- a/drivers/watchdog/hpwdt.c +++ b/drivers/watchdog/hpwdt.c @@ -21,6 +21,7 @@ #include <linux/types.h> #include <linux/watchdog.h> #include <asm/nmi.h> +#include <linux/crash_dump.h> #define HPWDT_VERSION "2.0.3" #define SECS_TO_TICKS(secs) ((secs) * 1000 / 128) @@ -334,6 +335,11 @@ static int hpwdt_init_one(struct pci_dev *dev, watchdog_set_nowayout(&hpwdt_dev, nowayout); watchdog_init_timeout(&hpwdt_dev, soft_margin, NULL); + if (is_kdump_kernel()) { + pretimeout = 0; + kdumptimeout = 0; + } + if (pretimeout && hpwdt_dev.timeout <= PRETIMEOUT_SEC) { dev_warn(&dev->dev, "timeout <= pretimeout. Setting pretimeout to zero\n"); pretimeout = 0;
NMIs received during the crash path are problematic as hpwdt_pretimeout handling of the NMI would cause a reentry into kdump. The situation is complicated in that I/O errors can be signaled as NMI circumventing hpwdt_pretimeout's attempt to not claim NMI not associated with either the WDT or the iLO NMI switch. These NMI can additionally cause a secondary NMI which cause the system to hang. By disabling pretimeout and hpwdtimeout in crash path we both reduce the risk of receiving an NMI and simuletaneously leave the WDT running (if it was already in use) to allow the WDT to break the system out of hangs by the WDT reset. Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com> --- drivers/watchdog/hpwdt.c | 6 ++++++ 1 file changed, 6 insertions(+)