On 08/17/2015 09:54 PM, 河合英宏 / KAWAI，HIDEHIRO wrote: >> From: Corey Minyard [mailto:tcminy...@gmail.com] On Behalf Of Corey Minyard >> >> This patch will break ATN handling on the interfaces. So we can't do this. > I understand. So how about doing like this: > > /* All states wait for ibf, so just do it here. */ > - if (!check_ibf(kcs, status, time)) > + if (kcs->state != KCS_IDLE && !check_ibf(kcs, status, time)) > return SI_SM_CALL_WITH_DELAY; > > I think it is not necessary to wait IBF when the state is IDLE. > In this way, we can also handle the ATN case.
I think it would be more reliable to go up a level and add a timeout. One should be there, anyway. I thought they were all covered, but I may have missed something. -corey > > Regards, > > Hidehiro Kawai > Hitachi, Ltd. Research & Development Group > >> It's going to be extremely hard to recover if the BMC is not working >> correctly when a panic happens. I'm not sure what can be done, but if >> you can fix it another way it would be good. >> >> -corey >> >> On 07/27/2015 12:55 AM, Hidehiro Kawai wrote: >>> If a BMC is unresponsive for some reason, it ends up completing >>> the requested message as an error, then kcs_event() is called once >>> to advance the state machine. However, since the BMC is >>> unresponsive now, the status of the KCS interface may not be >>> idle. As the result, the state machine can continue to run and >>> comsume CPU time indefinitely even if there is no more request >>> message. Moreover, if this happens in run-to-completion mode >>> (i.e. context of panic_event()), the kernel hangs up. >>> >>> To fix this problem, this patch ignores kcs_event() call if there >>> is no request message to be processed. >>> >>> Signed-off-by: Hidehiro Kawai <hidehiro.kawai...@hitachi.com> >>> --- >>> drivers/char/ipmi/ipmi_kcs_sm.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/drivers/char/ipmi/ipmi_kcs_sm.c >>> b/drivers/char/ipmi/ipmi_kcs_sm.c >>> index 8c25f59..0e187fb 100644 >>> --- a/drivers/char/ipmi/ipmi_kcs_sm.c >>> +++ b/drivers/char/ipmi/ipmi_kcs_sm.c >>> @@ -353,6 +353,10 @@ static enum si_sm_result kcs_event(struct si_sm_data >>> *kcs, long time) >>> if (kcs_debug & KCS_DEBUG_STATES) >>> printk(KERN_DEBUG "KCS: State = %d, %x\n", kcs->state, status); >>> >>> + /* We don't want to run the state machine when the state is IDLE */ >>> + if (kcs->state == KCS_IDLE) >>> + return SI_SM_IDLE; >>> + >>> /* All states wait for ibf, so just do it here. */ >>> if (!check_ibf(kcs, status, time)) >>> return SI_SM_CALL_WITH_DELAY; >>> >>> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
