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Date: Tue, 7 Jun 2011 14:18:07 +0900
Message-ID: <BANLkTin3Q1cO0-q50fEye7=7KHxTgKmhTg@mail.gmail.com>
Subject: Re: [PATCH v2 06/11] Bluetooth: Advertising entries lifetime
From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To: Andre Guedes <andre.guedes@openbossa.org>
Cc: linux-bluetooth@vger.kernel.org
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Sender: linux-bluetooth-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi Andre,

On Sat, May 21, 2011 at 9:10 AM, Andre Guedes
<andre.guedes@openbossa.org> wrote:
> This patch adds a timer to clear 'adv_entries' after three minutes.
>
> After some amount of time, the advertising entries cached during
> the last LE scan should be considered expired and they should be
> removed from the advertising cache.
>
> It was chosen a three minutes timeout as an initial attempt. This
> value might change in future.
>
> Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
> ---
> ?include/net/bluetooth/hci_core.h | ? ?2 ++
> ?net/bluetooth/hci_core.c ? ? ? ? | ? 14 ++++++++++++++
> ?net/bluetooth/hci_event.c ? ? ? ?| ? ?6 +++++-
> ?3 files changed, 21 insertions(+), 1 deletions(-)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 10dfb85..af4b0ed 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -188,6 +188,7 @@ struct hci_dev {
> ? ? ? ?struct list_head ? ? ? ?remote_oob_data;
>
> ? ? ? ?struct list_head ? ? ? ?adv_entries;
> + ? ? ? struct timer_list ? ? ? adv_timer;
>
> ? ? ? ?struct hci_dev_stats ? ?stat;
>
> @@ -535,6 +536,7 @@ int hci_add_remote_oob_data(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 *hash,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?u8 *randomizer);
> ?int hci_remove_remote_oob_data(struct hci_dev *hdev, bdaddr_t *bdaddr);
>
> +#define ADV_CLEAR_TIMEOUT (3*60*HZ) /* Three minutes */
> ?int hci_adv_entries_clear(struct hci_dev *hdev);
> ?struct adv_entry *hci_find_adv_entry(struct hci_dev *hdev, bdaddr_t *bdaddr);
> ?int hci_add_adv_entry(struct hci_dev *hdev,
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index dd27f97..5040c3f 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1204,6 +1204,17 @@ int hci_add_remote_oob_data(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 *hash,
> ? ? ? ?return 0;
> ?}
>
> +static void hci_clear_adv_cache(unsigned long arg)
> +{
> + ? ? ? struct hci_dev *hdev = (void *) arg;
> +
> + ? ? ? hci_dev_lock(hdev);
> +
> + ? ? ? hci_adv_entries_clear(hdev);
> +
> + ? ? ? hci_dev_unlock(hdev);
> +}
> +
> ?int hci_adv_entries_clear(struct hci_dev *hdev)
> ?{
> ? ? ? ?struct adv_entry *entry, *tmp;
> @@ -1332,6 +1343,8 @@ int hci_register_dev(struct hci_dev *hdev)
> ? ? ? ?INIT_LIST_HEAD(&hdev->remote_oob_data);
>
> ? ? ? ?INIT_LIST_HEAD(&hdev->adv_entries);
> + ? ? ? setup_timer(&hdev->adv_timer, hci_clear_adv_cache,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? (unsigned long) hdev);
>
> ? ? ? ?INIT_WORK(&hdev->power_on, hci_power_on);
> ? ? ? ?INIT_WORK(&hdev->power_off, hci_power_off);
> @@ -1405,6 +1418,7 @@ int hci_unregister_dev(struct hci_dev *hdev)
> ? ? ? ?hci_unregister_sysfs(hdev);
>
> ? ? ? ?hci_del_off_timer(hdev);
> + ? ? ? del_timer(&hdev->adv_timer);
>
> ? ? ? ?destroy_workqueue(hdev->workqueue);
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 85e12d8..8d6dc1e 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -859,8 +859,12 @@ static void hci_cc_le_set_scan_enable(struct hci_dev *hdev,
>
> ? ? ? ?hci_dev_lock(hdev);
>
> - ? ? ? if (param_scan_enable == 0x01)
> + ? ? ? if (param_scan_enable == 0x01) {
> + ? ? ? ? ? ? ? del_timer(&hdev->adv_timer);
> ? ? ? ? ? ? ? ?hci_adv_entries_clear(hdev);
> + ? ? ? } else if (param_scan_enable == 0x00) {
> + ? ? ? ? ? ? ? mod_timer(&hdev->adv_timer, jiffies + ADV_CLEAR_TIMEOUT);
> + ? ? ? }
>
> ? ? ? ?hci_dev_unlock(hdev);
> ?}
> --
> 1.7.4.1

Maybe we should not trigger the timer if the we are connected to the
device, this would be very convenient if a disconnect happen for
unknown reason e.g. bug or crash so we can quickly reconnect without
having to scan again, once disconnected then we start the entry timer,
what do you think?


-- 
Luiz Augusto von Dentz
Computer Engineer