linux-kernel - Re: [PATCH] ipmi: simplify duplicated if condition

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Date:   Mon, 25 Oct 2021 16:07:52 -0500
From:   Corey Minyard <minyard@....org>
To:     Wan Jiabing <wanjiabing@...o.com>
Cc:     openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, kael_w@...h.net
Subject: Re: [PATCH] ipmi: simplify duplicated if condition

On Sun, Oct 24, 2021 at 09:22:06PM -0400, Wan Jiabing wrote:
> There are 5 duplicated 'if' conditions to judge the 'run_to_completion',
> which looks redundant. And there is no function to modify this variable.

It's modified in panic_event().

> 
> Reduce the 'if' conditions from 5 times to 1 time can make code easy to
> understand and fix following coccicheck warning:
> 
> ./drivers/char/ipmi/ipmi_msghandler.c :4771:2-19: ERROR: nested
> lock+irqsave that reuses flags from line 4764.

I'm not sure this matters that much.  The comments are messed up a bit,
and probably need to be reworked.  But I'm not inclined to take this.

-corey

> 
> Signed-off-by: Wan Jiabing <wanjiabing@...o.com>
> ---
>  drivers/char/ipmi/ipmi_msghandler.c | 38 ++++++++++++++---------------
>  1 file changed, 18 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index a60201d3f735..072da25124cf 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -4756,32 +4756,30 @@ void ipmi_smi_msg_received(struct ipmi_smi *intf,
>  	unsigned long flags = 0; /* keep us warning-free. */
>  	int run_to_completion = intf->run_to_completion;
>  
> -	/*
> -	 * To preserve message order, we keep a queue and deliver from
> -	 * a tasklet.
> -	 */
> -	if (!run_to_completion)
> +	if (!run_to_completion) {
> +		/*
> +		 * To preserve message order, we keep a queue and deliver from
> +		 * a tasklet.
> +		 */
>  		spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
> -	list_add_tail(&msg->link, &intf->waiting_rcv_msgs);
> -	if (!run_to_completion)
> +		list_add_tail(&msg->link, &intf->waiting_rcv_msgs);
>  		spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock,
>  				       flags);
> -
> -	if (!run_to_completion)
>  		spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
> -	/*
> -	 * We can get an asynchronous event or receive message in addition
> -	 * to commands we send.
> -	 */
> -	if (msg == intf->curr_msg)
> -		intf->curr_msg = NULL;
> -	if (!run_to_completion)
> +		/*
> +		 * We can get an asynchronous event or receive message in addition
> +		 * to commands we send.
> +		 */
> +		if (msg == intf->curr_msg)
> +			intf->curr_msg = NULL;
>  		spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
> -
> -	if (run_to_completion)
> -		smi_recv_tasklet(&intf->recv_tasklet);
> -	else
>  		tasklet_schedule(&intf->recv_tasklet);
> +	} else {
> +		list_add_tail(&msg->link, &intf->waiting_rcv_msgs);
> +		if (msg == intf->curr_msg)
> +			intf->curr_msg = NULL;
> +		smi_recv_tasklet(&intf->recv_tasklet);
> +	}
>  }
>  EXPORT_SYMBOL(ipmi_smi_msg_received);
>  
> -- 
> 2.20.1
>