Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: 7BNfCakLMaEFZGcEC5Yf4najxrgrYw35gNWEi90LdH5zCqNyScSHccZuQa6PfelIkZqERYuIkD
 XD9qo1W2t5Xg==
IronPort-SDR: yX3P1NLute2OCFJbEoV2QgCeJ3Khe2GYWQ1s2O/XgWeGaIkBy0U6njMb8AAT2MWShOKKjD80aN
 4NWoOOjn9brw==
Date:   Fri, 23 Oct 2020 15:35:44 +0300
From:   Heikki Krogerus <heikki.krogerus@linux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org,
        Saravana Kannan <saravanak@google.com>,
        linux-acpi@vger.kernel.org,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Ferry Toth <fntoth@gmail.com>
Subject: Re: [PATCH v1 2/2] device property: Don't clear secondary pointer
 for shared primary firmware node
Message-ID: <20201023123544.GB614478@kuha.fi.intel.com>
References: <20201022184100.71659-1-andriy.shevchenko@linux.intel.com>
 <20201022184100.71659-2-andriy.shevchenko@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20201022184100.71659-2-andriy.shevchenko@linux.intel.com>
Precedence: bulk

On Thu, Oct 22, 2020 at 09:41:00PM +0300, Andy Shevchenko wrote:
> It appears that firmware nodes can be shared between devices. In such case
> when a (child) device is about to be deleted, its firmware node may be shared
> and ACPI_COMPANION_SET(..., NULL) call for it breaks the secondary link
> of the shared primary firmware node.
> 
> In order to prevent that, check, if the device has a parent and parent's
> firmware node is shared with its child, and avoid crashing the link.
> 
> Fixes: c15e1bdda436 ("device property: Fix the secondary firmware node handling in set_primary_fwnode()")
> Reported-by: Ferry Toth <fntoth@gmail.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

FWIW:

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/base/core.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 41feab679fa1..78114ddac755 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -4264,6 +4264,7 @@ static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
>   */
>  void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
>  {
> +	struct device *parent = dev->parent;
>  	struct fwnode_handle *fn = dev->fwnode;
>  
>  	if (fwnode) {
> @@ -4278,7 +4279,8 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
>  	} else {
>  		if (fwnode_is_primary(fn)) {
>  			dev->fwnode = fn->secondary;
> -			fn->secondary = ERR_PTR(-ENODEV);
> +			if (!(parent && fn == parent->fwnode))
> +				fn->secondary = ERR_PTR(-ENODEV);
>  		} else {
>  			dev->fwnode = NULL;
>  		}
> -- 
> 2.28.0

-- 
heikki