Re: [PATCH v10 8/9] platform/chrome: Protect cros_ec_device lifecycle with revocable

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, May 08, 2026 at 06:54:47PM +0800, Tzung-Bi Shih wrote:
>  struct cros_ec_device *cros_ec_device_alloc(struct device *dev)
> @@ -47,6 +49,15 @@ struct cros_ec_device *cros_ec_device_alloc(struct device *dev)
>  	if (!ec_dev)
>  		return NULL;
>  
> +	ec_dev->its_rev = revocable_alloc(ec_dev);
> +	if (!ec_dev->its_rev)
> +		return NULL;
> +	/*
> +	 * Drop the extra reference for the caller as the caller is the
> +	 * resource provider.
> +	 */
> +	revocable_put(ec_dev->its_rev);
> +
>  	ec_dev->din_size = sizeof(struct ec_host_response) +
>  			   sizeof(struct ec_response_get_protocol_info) +
>  			   EC_MAX_RESPONSE_OVERHEAD;

FWIW I am still very much against seeing any revokable concept used
*between two drivers*. That will turn the kernel's lifetime model into
spaghetti code.

Your other series where you only have to change
drivers/platform/chrome/cros_ec_chardev.c just confirms how wrong this
approach is.

Given you say this is such a bug I think you really should be sending
a series that is patches 5 through 7 from the other series and a
simple rwsem instead of misc_deregister_sync() to deal with this bug
ASAP. No need to complicate a simple bug fix in a driver with all
these core changes.

Once the bug is fixed you can continue to try to propose more general
solutions.

Jason