linux-kernel - Re: [PATCH v2 1/3] xen/events: Cleanup find

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Message-ID: <de9005bf-c858-4e7e-bea8-33e5ea2424fc@suse.com>
Date: Tue, 26 Aug 2025 09:22:10 +0200
From: Jan Beulich <jbeulich@...e.com>
To: Jason Andryuk <jason.andryuk@....com>
Cc: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
 Juergen Gross <jgross@...e.com>, Stefano Stabellini
 <sstabellini@...nel.org>,
 Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
Subject: Re: [PATCH v2 1/3] xen/events: Cleanup find_virq() return codes

On 26.08.2025 02:55, Jason Andryuk wrote:
> rc is overwritten by the evtchn_status hypercall in each iteration, so
> the return value will be whatever the last iteration is.

Which may even be a false "success". Especially for that it feels like ...

>  Change to an
> explicit -ENOENT for an un-found virq and return 0 on a successful
> match.
> 
> Signed-off-by: Jason Andryuk <jason.andryuk@....com>

... this also wants a Fixes: tag and perhaps a Cc: to stable@.

> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -1318,7 +1318,7 @@ static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn)
>  {
>  	struct evtchn_status status;
>  	evtchn_port_t port;
> -	int rc = -ENOENT;
> +	int rc;

Maybe best to also move this into the more narrow scope (loop body)?
Either way:
Reviewed-by: Jan Beulich <jbeulich@...e.com>

>  	memset(&status, 0, sizeof(status));

Having this outside of the loop is a little odd, too: It makes assumptions
on the behavior of the hypervisor (like not altering the structure upon
error). Yet likely not something to deal with right here.

Jan