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From: Bharat Bhushan <bbhushan2@marvell.com>
To: Dongsheng Yang <dongsheng.yang@easystack.cn>,
        "dan.j.williams@intel.com"
	<dan.j.williams@intel.com>,
        "axboe@kernel.dk" <axboe@kernel.dk>
CC: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>,
        Dongsheng Yang
	<dongsheng.yang.linux@gmail.com>
Subject: RE: [EXTERNAL] [PATCH 4/7] cbd: introduce cbd_host
Thread-Topic: [EXTERNAL] [PATCH 4/7] cbd: introduce cbd_host
Thread-Index: AQHalIpkvEF/TJb2IEC//+PWL2n/SLF4f8FA
Date: Thu, 25 Apr 2024 05:51:50 +0000
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 <20240422071606.52637-5-dongsheng.yang@easystack.cn>
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> -----Original Message-----
> From: Dongsheng Yang <dongsheng.yang@easystack.cn>
> Sent: Monday, April 22, 2024 12:46 PM
> To: dan.j.williams@intel.com; axboe@kernel.dk
> Cc: linux-block@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> cxl@vger.kernel.org; Dongsheng Yang <dongsheng.yang.linux@gmail.com>
> Subject: [EXTERNAL] [PATCH 4/7] cbd: introduce cbd_host
>=20
> Prioritize security for external emails: Confirm sender and content safet=
y
> before clicking links or opening attachments
>=20
> ----------------------------------------------------------------------
> From: Dongsheng Yang <dongsheng.yang.linux@gmail.com>
>=20
> The "cbd_host" represents a host node. Each node needs to be registered
> before it can use the "cbd_transport". After registration, the node's
> information, such as its hostname, will be recorded in the "hosts" area o=
f this
> transport. Through this mechanism, we can know which nodes are currently
> using each transport.
>=20
> Signed-off-by: Dongsheng Yang <dongsheng.yang.linux@gmail.com>
> ---
>  drivers/block/cbd/Makefile        |   2 +-
>  drivers/block/cbd/cbd_host.c      | 123
> ++++++++++++++++++++++++++++++
>  drivers/block/cbd/cbd_transport.c |   8 ++
>  3 files changed, 132 insertions(+), 1 deletion(-)  create mode 100644
> drivers/block/cbd/cbd_host.c
>=20
> diff --git a/drivers/block/cbd/Makefile b/drivers/block/cbd/Makefile inde=
x
> c581ae96732b..2389a738b12b 100644
> --- a/drivers/block/cbd/Makefile
> +++ b/drivers/block/cbd/Makefile
> @@ -1,3 +1,3 @@
> -cbd-y :=3D cbd_main.o cbd_transport.o cbd_channel.o
> +cbd-y :=3D cbd_main.o cbd_transport.o cbd_channel.o cbd_host.o
>=20
>  obj-$(CONFIG_BLK_DEV_CBD) +=3D cbd.o
> diff --git a/drivers/block/cbd/cbd_host.c b/drivers/block/cbd/cbd_host.c =
new
> file mode 100644 index 000000000000..892961f5f1b2
> --- /dev/null
> +++ b/drivers/block/cbd/cbd_host.c
> @@ -0,0 +1,123 @@
> +#include "cbd_internal.h"
> +
> +static ssize_t cbd_host_name_show(struct device *dev,
> +			       struct device_attribute *attr,
> +			       char *buf)
> +{
> +	struct cbd_host_device *host;
> +	struct cbd_host_info *host_info;
> +
> +	host =3D container_of(dev, struct cbd_host_device, dev);
> +	host_info =3D host->host_info;
> +
> +	cbdt_flush_range(host->cbdt, host_info, sizeof(*host_info));
> +
> +	if (host_info->state =3D=3D cbd_host_state_none)
> +		return 0;
> +
> +	if (strlen(host_info->hostname) =3D=3D 0)
> +		return 0;

Sprintf is safe to provide zero length source buffer. Maybe this check can =
be removed.

> +
> +	return sprintf(buf, "%s\n", host_info->hostname); }
> +
> +static DEVICE_ATTR(hostname, 0400, cbd_host_name_show, NULL);
> +
> +CBD_OBJ_HEARTBEAT(host);
> +
> +static struct attribute *cbd_host_attrs[] =3D {
> +	&dev_attr_hostname.attr,
> +	&dev_attr_alive.attr,
> +	NULL
> +};
> +
> +static struct attribute_group cbd_host_attr_group =3D {
> +	.attrs =3D cbd_host_attrs,
> +};
> +
> +static const struct attribute_group *cbd_host_attr_groups[] =3D {
> +	&cbd_host_attr_group,
> +	NULL
> +};
> +
> +static void cbd_host_release(struct device *dev) { }
> +
> +struct device_type cbd_host_type =3D {
> +	.name		=3D "cbd_host",
> +	.groups		=3D cbd_host_attr_groups,
> +	.release	=3D cbd_host_release,
> +};
> +
> +struct device_type cbd_hosts_type =3D {
> +	.name		=3D "cbd_hosts",
> +	.release	=3D cbd_host_release,
> +};
> +
> +int cbd_host_register(struct cbd_transport *cbdt, char *hostname) {
> +	struct cbd_host *host;
> +	struct cbd_host_info *host_info;
> +	u32 host_id;
> +	int ret;
> +
> +	if (cbdt->host) {
> +		return -EEXIST;
> +	}
> +
> +	if (strlen(hostname) =3D=3D 0) {
> +		return -EINVAL;
> +	}

Un-necessary braces

Thanks
-Bharat

> +
> +	ret =3D cbdt_get_empty_host_id(cbdt, &host_id);
> +	if (ret < 0) {
> +		return ret;
> +	}
> +
> +	host =3D kzalloc(sizeof(struct cbd_host), GFP_KERNEL);
> +	if (!host) {
> +		return -ENOMEM;
> +	}
> +
> +	host->host_id =3D host_id;
> +	host->cbdt =3D cbdt;
> +	INIT_DELAYED_WORK(&host->hb_work, host_hb_workfn);
> +
> +	host_info =3D cbdt_get_host_info(cbdt, host_id);
> +	host_info->state =3D cbd_host_state_running;
> +	memcpy(host_info->hostname, hostname, CBD_NAME_LEN);
> +
> +	cbdt_flush_range(cbdt, host_info, sizeof(*host_info));
> +
> +	host->host_info =3D host_info;
> +	cbdt->host =3D host;
> +
> +	queue_delayed_work(cbd_wq, &host->hb_work, 0);
> +
> +	return 0;
> +}
> +
> +int cbd_host_unregister(struct cbd_transport *cbdt) {
> +	struct cbd_host *host =3D cbdt->host;
> +	struct cbd_host_info *host_info;
> +
> +	if (!host) {
> +		cbd_err("This host is not registered.");
> +		return 0;
> +	}
> +
> +	cancel_delayed_work_sync(&host->hb_work);
> +	host_info =3D host->host_info;
> +	memset(host_info->hostname, 0, CBD_NAME_LEN);
> +	host_info->alive_ts =3D 0;
> +	host_info->state =3D cbd_host_state_none;
> +
> +	cbdt_flush_range(cbdt, host_info, sizeof(*host_info));
> +
> +	cbdt->host =3D NULL;
> +	kfree(cbdt->host);
> +
> +	return 0;
> +}
> diff --git a/drivers/block/cbd/cbd_transport.c
> b/drivers/block/cbd/cbd_transport.c
> index 3a4887afab08..682d0f45ce9e 100644
> --- a/drivers/block/cbd/cbd_transport.c
> +++ b/drivers/block/cbd/cbd_transport.c
> @@ -571,6 +571,7 @@ int cbdt_unregister(u32 tid)
>  	}
>  	mutex_unlock(&cbdt->lock);
>=20
> +	cbd_host_unregister(cbdt);
>  	device_unregister(&cbdt->device);
>  	cbdt_dax_release(cbdt);
>  	cbdt_destroy(cbdt);
> @@ -624,8 +625,15 @@ int cbdt_register(struct cbdt_register_options
> *opts)
>  		goto dax_release;
>  	}
>=20
> +	ret =3D cbd_host_register(cbdt, opts->hostname);
> +	if (ret) {
> +		goto dev_unregister;
> +	}
> +
>  	return 0;
>=20
> +devs_exit:
> +	cbd_host_unregister(cbdt);
>  dev_unregister:
>  	device_unregister(&cbdt->device);
>  dax_release:
> --
> 2.34.1
>=20