On Thu, May 13, 2021 at 02:26:36PM +0200, Petr Pavlu wrote:
> When an IPMI watchdog timer is being stopped in ipmi_close() or
> ipmi_ioctl(WDIOS_DISABLECARD), the current watchdog action is updated to
> WDOG_TIMEOUT_NONE and _ipmi_set_timeout(IPMI_SET_TIMEOUT_NO_HB) is called
> to install this action. The latter function ends up invoking
> __ipmi_set_timeout() which makes the actual 'Set Watchdog Timer' IPMI
> request.
>
> For IPMI 1.0, this operation results in fully stopping the watchdog timer.
> For IPMI >= 1.5, function __ipmi_set_timeout() always specifies the "don't
> stop" flag in the prepared 'Set Watchdog Timer' IPMI request. This causes
> that the watchdog timer has its action correctly updated to 'none' but the
> timer continues to run. A problem is that IPMI firmware can then still log
> an expiration event when the configured timeout is reached, which is
> unexpected because the watchdog timer was requested to be stopped.
>
> The patch fixes this problem by not setting the "don't stop" flag in
> __ipmi_set_timeout() when the current action is WDOG_TIMEOUT_NONE which
> results in stopping the watchdog timer. This makes the behaviour for
> IPMI >= 1.5 consistent with IPMI 1.0. It also matches the logic in
> __ipmi_heartbeat() which does not allow to reset the watchdog if the
> current action is WDOG_TIMEOUT_NONE as that would start the timer.
Yes, I believe this is correct, though it took a bit to be sure :).
Applied for linux-next. I'm also requesting backport to stable kernels.
-corey
>
> Signed-off-by: Petr Pavlu <petr.pa...@suse.com>
> ---
> drivers/char/ipmi/ipmi_watchdog.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_watchdog.c
> b/drivers/char/ipmi/ipmi_watchdog.c
> index 32c334e34d55..e4ff3b50de7f 100644
> --- a/drivers/char/ipmi/ipmi_watchdog.c
> +++ b/drivers/char/ipmi/ipmi_watchdog.c
> @@ -371,16 +371,18 @@ static int __ipmi_set_timeout(struct ipmi_smi_msg
> *smi_msg,
> data[0] = 0;
> WDOG_SET_TIMER_USE(data[0], WDOG_TIMER_USE_SMS_OS);
>
> - if ((ipmi_version_major > 1)
> - || ((ipmi_version_major == 1) && (ipmi_version_minor >= 5))) {
> - /* This is an IPMI 1.5-only feature. */
> - data[0] |= WDOG_DONT_STOP_ON_SET;
> - } else if (ipmi_watchdog_state != WDOG_TIMEOUT_NONE) {
> - /*
> - * In ipmi 1.0, setting the timer stops the watchdog, we
> - * need to start it back up again.
> - */
> - hbnow = 1;
> + if (ipmi_watchdog_state != WDOG_TIMEOUT_NONE) {
> + if ((ipmi_version_major > 1) ||
> + ((ipmi_version_major == 1) && (ipmi_version_minor >= 5))) {
> + /* This is an IPMI 1.5-only feature. */
> + data[0] |= WDOG_DONT_STOP_ON_SET;
> + } else {
> + /*
> + * In ipmi 1.0, setting the timer stops the watchdog, we
> + * need to start it back up again.
> + */
> + hbnow = 1;
> + }
> }
>
> data[1] = 0;
> --
> 2.26.2
>
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