netdev - Re: [PATCH v2 1/4] driver core: Make parameter check consistent for API cluster device_(for_each|find)

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Message-ID: <66c491c32091d_2ddc24294e8@iweiny-mobl.notmuch>
Date: Tue, 20 Aug 2024 07:53:23 -0500
From: Ira Weiny <ira.weiny@...el.com>
To: Zijun Hu <zijun_hu@...oud.com>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>,
	Davidlohr Bueso <dave@...olabs.net>, Jonathan Cameron
	<jonathan.cameron@...wei.com>, Dave Jiang <dave.jiang@...el.com>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Takashi Sakamoto <o-takashi@...amocchi.jp>,
	"Timur Tabi" <timur@...nel.org>, "David S. Miller" <davem@...emloft.net>,
	"Eric Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
 Abeni <pabeni@...hat.com>
CC: Zijun Hu <zijun_hu@...oud.com>, <linux-kernel@...r.kernel.org>,
	<linux-cxl@...r.kernel.org>, <linux1394-devel@...ts.sourceforge.net>,
	<netdev@...r.kernel.org>, Zijun Hu <quic_zijuhu@...cinc.com>
Subject: Re: [PATCH v2 1/4] driver core: Make parameter check consistent for
 API cluster device_(for_each|find)_child()

Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@...cinc.com>
> 
> The following API cluster takes the same type parameter list, but do not
> have consistent parameter check as shown below.
> 
> device_for_each_child(struct device *parent, ...)  // check (!parent->p)
> device_for_each_child_reverse(struct device *parent, ...) // same as above
> device_find_child(struct device *parent, ...)      // check (!parent)
> 

Seems reasonable.

What about device_find_child_by_name()?

> Fixed by using consistent check (!parent || !parent->p) for the cluster.
> 
> Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
> ---
>  drivers/base/core.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 1688e76cb64b..b1dd8c5590dc 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -4004,7 +4004,7 @@ int device_for_each_child(struct device *parent, void *data,
>  	struct device *child;
>  	int error = 0;
>  
> -	if (!parent->p)
> +	if (!parent || !parent->p)
>  		return 0;
>  
>  	klist_iter_init(&parent->p->klist_children, &i);
> @@ -4034,7 +4034,7 @@ int device_for_each_child_reverse(struct device *parent, void *data,
>  	struct device *child;
>  	int error = 0;
>  
> -	if (!parent->p)
> +	if (!parent || !parent->p)
>  		return 0;
>  
>  	klist_iter_init(&parent->p->klist_children, &i);
> @@ -4068,7 +4068,7 @@ struct device *device_find_child(struct device *parent, void *data,
>  	struct klist_iter i;
>  	struct device *child;
>  
> -	if (!parent)
> +	if (!parent || !parent->p)

Perhaps this was just a typo which should have been.

	if (!parent->p)
?

I think there is an expectation that none of these are called with a NULL
parent.

Ira

>  		return NULL;
>  
>  	klist_iter_init(&parent->p->klist_children, &i);
> 
> -- 
> 2.34.1
>