linux-kernel - Re: [PATCH 1/1] ipmi: setting mod_timer for read_event

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Date:	Mon, 02 Dec 2013 15:03:38 -0600
From:	Corey Minyard <minyard@....org>
To:	Srinivas_G_Gowda@...l.com
CC:	tcminyard@...il.com, linux-kernel@...r.kernel.org,
	openipmi@...sta.com
Subject: Re: [PATCH 1/1] ipmi: setting mod_timer for read_event_msg buffer
 cmd

On 12/02/2013 08:49 AM, Srinivas_G_Gowda@...l.com wrote:
> Thanks for the patch Corey. 
> I am afraid that the system does not have interrupts enabled. It uses polling mode. 
>
> When the error is seen, I know for a fact that in function ipmi_thread() smi_result is SI_SM_CALL_WITH_DELAY, 
> I have some logs where in busy_wait always reads as 1. Not sure if it was ever set to 0. (ill check this again). 
> Ill anyway run the test using the patch that you have shared. 
>
> b/w would it harm if we were to do to something like this ?  

Unfortunately, that would start the timer unnecessarily.  You don't want
to start timers unnecessarily in the kernel or the power management
police will come after you.

The patch I sent did have this call in the non-idle portion of the
kernel thread and that should have done the same thing.  Plus, if you
are using the kernel thread, it's going to run periodically and should
kick things off again if they get stuck.  I'm suspicious now that
something else is going on.

-corey

>
> Signed-off-by: Srinivas Gowda <srinivas_g_gowda@...l.com>
> ---
>  drivers/char/ipmi/ipmi_si_intf.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> index 15e4a60..e23484f 100644
> --- a/drivers/char/ipmi/ipmi_si_intf.c
> +++ b/drivers/char/ipmi/ipmi_si_intf.c
> @@ -1008,6 +1008,7 @@ static int ipmi_thread(void *data)
>  		spin_unlock_irqrestore(&(smi_info->si_lock), flags);
>  		busy_wait = ipmi_thread_busy_wait(smi_result, smi_info,
>  						  &busy_until);
> +		ipmi_start_timer_if_necessary(smi_info);
>  		if (smi_result == SI_SM_CALL_WITHOUT_DELAY)
>  			; /* do nothing */
>  		else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait)

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