linux-kernel - Re: [PATCH v2 1/4] spi: allow ancillary devices to share parent's chip selects

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <8fbfcf7c-4acd-4a7f-a5a5-34baad84e1b2@baylibre.com>
Date: Sat, 7 Feb 2026 12:09:34 -0600
From: David Lechner <dlechner@...libre.com>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>,
 Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Nuno Sá
 <nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Olivier Moysan <olivier.moysan@...s.st.com>, Mark Brown
 <broonie@...nel.org>, linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org
Subject: Re: [PATCH v2 1/4] spi: allow ancillary devices to share parent's
 chip selects

On 2/6/26 10:07 AM, Antoniu Miclaus wrote:
> When registering an ancillary SPI device, the current code flags a chip
> select conflict with the parent device. This happens because the
> ancillary device intentionally uses one of the parent's chip selects,
> but __spi_add_device() checks against all existing devices including
> the parent.
> 
> Allow this by passing the parent device pointer to __spi_add_device()
> and skipping the conflict check when the existing device is the parent.
> 

...

>  static int spi_dev_check(struct device *dev, void *data)
>  {
>  	struct spi_device *spi = to_spi_device(dev);
> -	struct spi_device *new_spi = data;
> +	struct spi_dev_check_info *info = data;
> +	struct spi_device *new_spi = info->new_spi;
>  	int status, idx;
>  
> +	/*
> +	 * When registering an ancillary device, skip checking against the
> +	 * parent device since the ancillary is intentionally using one of
> +	 * the parent's chip selects.
> +	 */
> +	if (info->parent && spi == info->parent)

spi should never be NULL (or we would get a segfault later), so
if `(spi == info->parent)` should be enough.

> +		return 0;
> +
Reviewed-by: David Lechner <dlechner@...libre.com>