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Message-ID: <c278724b19ef43f58bc7940b202fcd4638906e5f.camel@iki.fi>
Subject: Re: [PATCH] Bluetooth: Make handle of hci_conn be unique
From:   Pauli Virtanen <pav@iki.fi>
To:     Ziyang Xuan <william.xuanziyang@huawei.com>,
        linux-bluetooth@vger.kernel.org
Date:   Wed, 11 Oct 2023 18:11:27 +0300
In-Reply-To: <20231011095731.1947052-1-william.xuanziyang@huawei.com>
References: <20231011095731.1947052-1-william.xuanziyang@huawei.com>
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Hi,

ke, 2023-10-11 kello 17:57 +0800, Ziyang Xuan kirjoitti:
> The handle of new hci_conn is always HCI_CONN_HANDLE_MAX + 1 if
> the handle of the first hci_conn entry in hci_dev->conn_hash->list
> is not HCI_CONN_HANDLE_MAX + 1. Use ida to manage the allocation of
> hci_conn->handle to make it be unique.
>=20
> Fixes: 9f78191cc9f1 ("Bluetooth: hci_conn: Always allocate unique handles=
")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---
>  include/net/bluetooth/hci_core.h |  2 ++
>  net/bluetooth/hci_conn.c         | 30 +++++++++++++-----------------
>  net/bluetooth/hci_core.c         |  3 +++
>  3 files changed, 18 insertions(+), 17 deletions(-)
>=20
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci=
_core.h
> index f36c1fd5d64e..a0c0e12e3a18 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -350,6 +350,8 @@ struct hci_dev {
>  	struct list_head list;
>  	struct mutex	lock;
> =20
> +	struct ida	unset_handle_ida;
> +
>  	const char	*name;
>  	unsigned long	flags;
>  	__u16		id;
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index 974631e652c1..6ec161bf569a 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -153,6 +153,9 @@ static void hci_conn_cleanup(struct hci_conn *conn)
> =20
>  	hci_conn_hash_del(hdev, conn);
> =20
> +	if (HCI_CONN_HANDLE_UNSET(conn->handle))
> +		ida_free(&hdev->unset_handle_ida, conn->handle);
> +

The conn handle is replaced in hci_conn_set_handle, so old handle from
IDA probably should be freed there too.

Sorry, didn't notice this on the first round.

le_conn_complete_evt also doesn't use hci_conn_set_handle but probably
should, which now starts to matter more.

>  	if (conn->cleanup)
>  		conn->cleanup(conn);
> =20
> @@ -929,29 +932,17 @@ static void cis_cleanup(struct hci_conn *conn)
>  	hci_le_remove_cig(hdev, conn->iso_qos.ucast.cig);
>  }
> =20
> -static u16 hci_conn_hash_alloc_unset(struct hci_dev *hdev)
> +static int hci_conn_hash_alloc_unset(struct hci_dev *hdev)
>  {
> -	struct hci_conn_hash *h =3D &hdev->conn_hash;
> -	struct hci_conn  *c;
> -	u16 handle =3D HCI_CONN_HANDLE_MAX + 1;
> -
> -	rcu_read_lock();
> -
> -	list_for_each_entry_rcu(c, &h->list, list) {
> -		/* Find the first unused handle */
> -		if (handle =3D=3D 0xffff || c->handle !=3D handle)
> -			break;
> -		handle++;
> -	}
> -	rcu_read_unlock();
> -
> -	return handle;
> +	return ida_alloc_range(&hdev->unset_handle_ida, HCI_CONN_HANDLE_MAX + 1=
,
> +			       U16_MAX, GFP_ATOMIC);
>  }
> =20
>  struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *=
dst,
>  			      u8 role)
>  {
>  	struct hci_conn *conn;
> +	int handle;
> =20
>  	BT_DBG("%s dst %pMR", hdev->name, dst);
> =20
> @@ -961,7 +952,12 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, =
int type, bdaddr_t *dst,
> =20
>  	bacpy(&conn->dst, dst);
>  	bacpy(&conn->src, &hdev->bdaddr);
> -	conn->handle =3D hci_conn_hash_alloc_unset(hdev);
> +	handle =3D hci_conn_hash_alloc_unset(hdev);
> +	if (unlikely(handle < 0)) {
> +		kfree(conn);
> +		return NULL;
> +	}
> +	conn->handle =3D handle;
>  	conn->hdev  =3D hdev;
>  	conn->type  =3D type;
>  	conn->role  =3D role;
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 195aea2198a9..65601aa52e0d 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -2535,6 +2535,8 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>  	mutex_init(&hdev->lock);
>  	mutex_init(&hdev->req_lock);
> =20
> +	ida_init(&hdev->unset_handle_ida);
> +
>  	INIT_LIST_HEAD(&hdev->mesh_pending);
>  	INIT_LIST_HEAD(&hdev->mgmt_pending);
>  	INIT_LIST_HEAD(&hdev->reject_list);
> @@ -2789,6 +2791,7 @@ void hci_release_dev(struct hci_dev *hdev)
>  	hci_codec_list_clear(&hdev->local_codecs);
>  	hci_dev_unlock(hdev);
> =20
> +	ida_destroy(&hdev->unset_handle_ida);
>  	ida_simple_remove(&hci_index_ida, hdev->id);
>  	kfree_skb(hdev->sent_cmd);
>  	kfree_skb(hdev->recv_event);

--=20
Pauli Virtanen