linux-kernel - Re: [PATCH 4/7] xen/events: remove some simple helpers from events

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Date:   Mon, 13 Nov 2023 17:35:09 +0000
From:   Oleksandr Tyshchenko <Oleksandr_Tyshchenko@...m.com>
To:     Juergen Gross <jgross@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Stefano Stabellini <sstabellini@...nel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH 4/7] xen/events: remove some simple helpers from
 events_base.c



On 16.10.23 09:28, Juergen Gross wrote:


Hello Juergen.


> The helper functions type_from_irq() and cpu_from_irq() are just one
> line functions used only internally.
> 
> Open code them where needed. At the same time modify and rename
> get_evtchn_to_irq() to return a struct irq_info instead of the IRQ
> number.
> 
> Signed-off-by: Juergen Gross <jgross@...e.com>



[snip]



> 
> @@ -1181,15 +1172,16 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip,
>   {
>   	int irq;
>   	int ret;
> +	struct irq_info *info;
>   
>   	if (evtchn >= xen_evtchn_max_channels())
>   		return -ENOMEM;


I assume this check is called here (*before* holding a lock) by 
intention, as evtchn_to_info() below contains the same check.

>   
>   	mutex_lock(&irq_mapping_update_lock);
>   
> -	irq = get_evtchn_to_irq(evtchn);
> +	info = evtchn_to_info(evtchn) >
> -	if (irq == -1) {
> +	if (!info) {
>   		irq = xen_allocate_irq_dynamic();
>   		if (irq < 0)
>   			goto out;
> @@ -1212,8 +1204,8 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip,
>   		 */
>   		bind_evtchn_to_cpu(evtchn, 0, false);
>   	} else {
> -		struct irq_info *info = info_for_irq(irq);
> -		WARN_ON(info == NULL || info->type != IRQT_EVTCHN);
> +		WARN_ON(info->type != IRQT_EVTCHN);
> +		irq = info->irq;
>   	}


This hunk doesn't apply clearly to the latest state, because of 
"9e90e58c11b7 xen: evtchn: Allow shared registration of IRQ handers" 
went in. Please rebase.


With that:
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>


Also checkpatch.pl warns about BUG_ON usage in several places, but again 
you didn't introduce them in current patch, just touched their args.


[snip]