Re: [PATCHv2] hsi: hsi_core: use kzalloc_flex

[Sebastian Reichel <sebastian.reichel@collabora.com>]

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Hi,

On Tue, Mar 17, 2026 at 12:58:19PM -0700, Rosen Penev wrote:
> Simplifies allocations by using a flexible array member in this struct.
> 
> Add __counted_by to get extra runtime analysis.
> 
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  v2: remove wrong null check
>  drivers/hsi/hsi_core.c  | 38 +++++++++++++++-----------------------
>  include/linux/hsi/hsi.h |  2 +-
>  2 files changed, 16 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/hsi/hsi_core.c b/drivers/hsi/hsi_core.c
> index 7cb2dcb30fdb..001bcadf4b8e 100644
> --- a/drivers/hsi/hsi_core.c
> +++ b/drivers/hsi/hsi_core.c
> @@ -342,13 +342,11 @@ static void hsi_controller_release(struct device *dev)
>  {
>  	struct hsi_controller *hsi = to_hsi_controller(dev);
> 
> -	kfree(hsi->port);
>  	kfree(hsi);
>  }
> 
>  static void hsi_port_release(struct device *dev)
>  {
> -	kfree(to_hsi_port(dev));

Why is this free being removed? This is freeing hsi->port[i], which
still has an extra allocation after your patch.

FWIW - it should be possible to further simplify things (in a
potential follow-up patch) that also drops this extra
allocation/free by simply embedding an array of 'struct hsi_port'
instead of a pointer array in 'struct hsi_controller'.

Greetings,

-- Sebastian

>  }
> 
>  /**
> @@ -446,7 +444,7 @@ void hsi_put_controller(struct hsi_controller *hsi)
>  		return;
> 
>  	for (i = 0; i < hsi->num_ports; i++)
> -		if (hsi->port && hsi->port[i])
> +		if (hsi->port[i])
>  			put_device(&hsi->port[i]->device);
>  	put_device(&hsi->device);
>  }
> @@ -462,39 +460,33 @@ EXPORT_SYMBOL_GPL(hsi_put_controller);
>  struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
>  {
>  	struct hsi_controller	*hsi;
> -	struct hsi_port		**port;
>  	unsigned int		i;
> 
>  	if (!n_ports)
>  		return NULL;
> 
> -	hsi = kzalloc_obj(*hsi, flags);
> +	hsi = kzalloc_flex(*hsi, port, n_ports, flags);
>  	if (!hsi)
>  		return NULL;
> -	port = kzalloc_objs(*port, n_ports, flags);
> -	if (!port) {
> -		kfree(hsi);
> -		return NULL;
> -	}
> +
>  	hsi->num_ports = n_ports;
> -	hsi->port = port;
>  	hsi->device.release = hsi_controller_release;
>  	device_initialize(&hsi->device);
> 
>  	for (i = 0; i < n_ports; i++) {
> -		port[i] = kzalloc_obj(**port, flags);
> -		if (port[i] == NULL)
> +		hsi->port[i] = kzalloc_obj(**hsi->port, flags);
> +		if (hsi->port[i] == NULL)
>  			goto out;
> -		port[i]->num = i;
> -		port[i]->async = hsi_dummy_msg;
> -		port[i]->setup = hsi_dummy_cl;
> -		port[i]->flush = hsi_dummy_cl;
> -		port[i]->start_tx = hsi_dummy_cl;
> -		port[i]->stop_tx = hsi_dummy_cl;
> -		port[i]->release = hsi_dummy_cl;
> -		mutex_init(&port[i]->lock);
> -		BLOCKING_INIT_NOTIFIER_HEAD(&port[i]->n_head);
> -		dev_set_name(&port[i]->device, "port%d", i);
> +		hsi->port[i]->num = i;
> +		hsi->port[i]->async = hsi_dummy_msg;
> +		hsi->port[i]->setup = hsi_dummy_cl;
> +		hsi->port[i]->flush = hsi_dummy_cl;
> +		hsi->port[i]->start_tx = hsi_dummy_cl;
> +		hsi->port[i]->stop_tx = hsi_dummy_cl;
> +		hsi->port[i]->release = hsi_dummy_cl;
> +		mutex_init(&hsi->port[i]->lock);
> +		BLOCKING_INIT_NOTIFIER_HEAD(&hsi->port[i]->n_head);
> +		dev_set_name(&hsi->port[i]->device, "port%d", i);
>  		hsi->port[i]->device.release = hsi_port_release;
>  		device_initialize(&hsi->port[i]->device);
>  	}
> diff --git a/include/linux/hsi/hsi.h b/include/linux/hsi/hsi.h
> index 6ca92bff02c6..ea6bef9b6012 100644
> --- a/include/linux/hsi/hsi.h
> +++ b/include/linux/hsi/hsi.h
> @@ -271,7 +271,7 @@ struct hsi_controller {
>  	struct module		*owner;
>  	unsigned int		id;
>  	unsigned int		num_ports;
> -	struct hsi_port		**port;
> +	struct hsi_port		*port[] __counted_by(num_ports);
>  };
> 
>  #define to_hsi_controller(dev) container_of(dev, struct hsi_controller, device)
> --
> 2.53.0
> 

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