linux-kernel - Re: [PATCH v11 01/20] cxl/port: Fix release of RCD endpoints

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Date:   Mon, 2 Oct 2023 15:14:43 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Robert Richter <rrichter@....com>
CC:     Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        "Davidlohr Bueso" <dave@...olabs.net>,
        Dave Jiang <dave.jiang@...el.com>, <linux-cxl@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Terry Bowman <terry.bowman@....com>
Subject: Re: [PATCH v11 01/20] cxl/port: Fix release of RCD endpoints

On Wed, 27 Sep 2023 17:43:20 +0200
Robert Richter <rrichter@....com> wrote:

> Binding and unbindind RCD endpoints (e.g. mem0 device) caused the
> corresponding endpoint not being released. Reason for that is the
> wrong port discovered for RCD endpoints. See cxl_mem_probe() for
> proper endpoint parent detection. Fix delete_endpoint() respectively.
> 
> Signed-off-by: Robert Richter <rrichter@....com>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

I wondered briefly if an access function of some type could be
used to hide this detail away. However it's messy enough that
that is a little tricky so I think we should just keep it
explicit in each location.  So as you have it here.

> ---
>  drivers/cxl/core/port.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 7ca01a834e18..d4572a02989a 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -1222,12 +1222,17 @@ static void delete_endpoint(void *data)
>  	struct cxl_memdev *cxlmd = data;
>  	struct cxl_port *endpoint = cxlmd->endpoint;
>  	struct cxl_port *parent_port;
> +	struct cxl_dport *dport;
>  	struct device *parent;
>  
> -	parent_port = cxl_mem_find_port(cxlmd, NULL);
> +	parent_port = cxl_mem_find_port(cxlmd, &dport);
>  	if (!parent_port)
>  		goto out;
> -	parent = &parent_port->dev;
> +
> +	if (dport->rch)
> +		parent = parent_port->uport_dev;
> +	else
> +		parent = &parent_port->dev;
>  
>  	device_lock(parent);
>  	if (parent->driver && !endpoint->dead) {