From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 3 Aug 2011 16:18:54 -0300 From: Gustavo Padovan To: Anderson Briglia Cc: linux-bluetooth@vger.kernel.org Subject: Re: [RFC 6/7] Bluetooth: Add RSSI Monitor timer and list lock Message-ID: <20110803191854.GE28119@joana> References: <1312310109-27082-1-git-send-email-anderson.briglia@openbossa.org> <1312310109-27082-7-git-send-email-anderson.briglia@openbossa.org> <20110803184826.GD28119@joana> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Briglia, * Anderson Briglia [2011-08-03 15:09:50 -0400]: > Hi Padovan, > > On Wed, Aug 3, 2011 at 2:48 PM, Gustavo Padovan wrote: > > Hi Briglia, > > > > * Anderson Briglia [2011-08-02 14:35:08 -0400]: > > > >> This is the polling mechanism to send HCI Read RSSI commands. The > >> command responses are used by the RSSI Monitor to get the current RSSI > >> value and calculate the current alert level for a given monitored > >> connection. > >> > >> This patch also adds read and write locks on rssi_monitor_list in > >> order to avoid race conditions. > >> > >> Signed-off-by: Anderson Briglia > >> --- > >>  include/net/bluetooth/hci_core.h |    3 + > >>  net/bluetooth/hci_core.c         |   12 +++++ > >>  net/bluetooth/mgmt.c             |   99 ++++++++++++++++++++++++++++++++++---- > >>  3 files changed, 104 insertions(+), 10 deletions(-) > >> > >> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h > >> index a3cf433..8ff3448 100644 > >> --- a/include/net/bluetooth/hci_core.h > >> +++ b/include/net/bluetooth/hci_core.h > >> @@ -211,6 +211,8 @@ struct hci_dev { > >> > >>       struct timer_list       le_scan_timer; > >> > >> +     struct timer_list       rssi_monitor_timer; > > > > call this rssi_timer is enough. > > > >> + > >>       struct hci_dev_stats    stat; > >> > >>       struct sk_buff_head     driver_init; > >> @@ -869,6 +871,7 @@ int mgmt_has_pending_stop_discov(u16 index); > >>  int mgmt_cancel_discovery(u16 index); > >>  int mgmt_is_interleaved_discovery(u16 index); > >>  int mgmt_do_interleaved_discovery(u16 index); > >> +void mgmt_do_read_rssi(struct hci_dev *hdev); > >> > >>  /* HCI info for socket */ > >>  #define hci_pi(sk) ((struct hci_pinfo *) sk) > >> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c > >> index c0c46bf..eb51b94 100644 > >> --- a/net/bluetooth/hci_core.c > >> +++ b/net/bluetooth/hci_core.c > >> @@ -1449,6 +1449,14 @@ static void hci_disable_le_scan(unsigned long arg) > >>       hci_send_cmd(hdev, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(cp), &cp); > >>  } > >> > >> +static void hci_do_read_rssi(unsigned long arg) > >> +{ > >> +     struct hci_dev *hdev = (void *) arg; > >> + > >> +     if (test_bit(HCI_UP, &hdev->flags)) > >> +             mgmt_do_read_rssi(hdev); > >> +} > >> + > >>  /* Register HCI device */ > >>  int hci_register_dev(struct hci_dev *hdev) > >>  { > >> @@ -1522,6 +1530,9 @@ int hci_register_dev(struct hci_dev *hdev) > >>       setup_timer(&hdev->le_scan_timer, hci_disable_le_scan, > >>                                               (unsigned long) hdev); > >> > >> +     setup_timer(&hdev->rssi_monitor_timer, hci_do_read_rssi, > >> +                                             (unsigned long) hdev); > >> + > >>       INIT_WORK(&hdev->power_on, hci_power_on); > >>       INIT_WORK(&hdev->power_off, hci_power_off); > >>       setup_timer(&hdev->off_timer, hci_auto_off, (unsigned long) hdev); > >> @@ -1604,6 +1615,7 @@ int hci_unregister_dev(struct hci_dev *hdev) > >>       hci_del_off_timer(hdev); > >>       del_timer(&hdev->adv_timer); > >>       del_timer(&hdev->le_scan_timer); > >> +     del_timer(&hdev->rssi_monitor_timer); > >> > >>       destroy_workqueue(hdev->workqueue); > >> > >> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c > >> index 65ddbff..b034290 100644 > >> --- a/net/bluetooth/mgmt.c > >> +++ b/net/bluetooth/mgmt.c > >> @@ -48,6 +48,8 @@ enum bt_device_type { > >>  #define RSSI_MONITOR_ALERT_LOW               0x01 > >>  #define RSSI_MONITOR_ALERT_HIGH              0x02 > >> > >> +#define RSSI_MONITOR_TIMEOUT         2000 > >> + > >>  struct pending_cmd { > >>       struct list_head list; > >>       __u16 opcode; > >> @@ -70,6 +72,9 @@ struct rssi_monitor { > >> > >>  static LIST_HEAD(rssi_monitor_list); > >> > >> +static rwlock_t rssi_monitor_list_lock; > >> +static DEFINE_RWLOCK(rssi_monitor_list_lock); > > > > Use a normal spinlock here. > > Ok. > > > >> + > >>  static int cmd_status(struct sock *sk, u16 index, u16 cmd, u8 status) > >>  { > >>       struct sk_buff *skb; > >> @@ -1916,21 +1921,46 @@ static struct rssi_monitor *rssi_monitor_find(u16 index, bdaddr_t *bdaddr) > >>       return NULL; > >>  } > >> > >> +static void rssi_monitor_start(u16 index) > >> +{ > >> +     struct hci_dev *hdev; > >> + > >> +     if (list_empty(&rssi_monitor_list)) > >> +             return; > >> + > >> +     hdev = hci_dev_get(index); > >> +     if (!hdev) > >> +             return; > >> + > >> +     mod_timer(&hdev->rssi_monitor_timer, jiffies + > >> +                     msecs_to_jiffies(RSSI_MONITOR_TIMEOUT)); > >> +     hci_dev_put(hdev); > >> +} > >> + > >>  static int rssi_monitor_add(u16 index, bdaddr_t *bdaddr, s8 low_trigger, > >>                                                       s8 high_trigger) > >>  { > >>       struct rssi_monitor *rm; > >> +     int err = 0; > >> > >> -     if (rssi_monitor_find(index, bdaddr)) > >> -             return -EEXIST; > >> +     write_lock_bh(&rssi_monitor_list_lock); > >> + > >> +     if (rssi_monitor_find(index, bdaddr)) { > >> +             err = -EEXIST; > >> +             goto out; > >> +     } > >> > >>       if (low_trigger < -127 || low_trigger > 128 || > >> -                     high_trigger < -127 || high_trigger > 128) > >> -             return -EINVAL; > >> +                     high_trigger < -127 || high_trigger > 128) { > >> +             err = -EINVAL; > >> +             goto out; > >> +     } > >> > >>       rm = kzalloc(sizeof(*rm), GFP_ATOMIC); > >> -     if (!rm) > >> -             return -ENOMEM; > >> +     if (!rm) { > >> +             err = -ENOMEM; > >> +             goto out; > >> +     } > >> > >>       rm->index = index; > >>       bacpy(&rm->bdaddr, bdaddr); > >> @@ -1940,20 +1970,46 @@ static int rssi_monitor_add(u16 index, bdaddr_t *bdaddr, s8 low_trigger, > >> > >>       list_add(&rm->list, &rssi_monitor_list); > >> > >> -     return 0; > >> +     rssi_monitor_start(index); > >> + > >> +out: > >> +     write_unlock_bh(&rssi_monitor_list_lock); > >> +     return err; > >>  } > >> > >>  static int rssi_monitor_remove(u16 index, bdaddr_t *bdaddr) > >>  { > >>       struct rssi_monitor *rm; > >> +     struct hci_dev *hdev; > >> +     int err = 0; > >> + > >> +     write_lock_bh(&rssi_monitor_list_lock); > >> > >>       rm = rssi_monitor_find(index, bdaddr); > >> -     if (!rm) > >> -             return -EINVAL; > >> +     if (!rm) { > >> +             err = -EINVAL; > >> +             goto out; > >> +     } > >> > >>       list_del(&rm->list); > >> +     kfree(rm); > >> > >> -     return 0; > >> +     if (!list_empty(&rssi_monitor_list)) > >> +             goto out; > > > > This need to be a per hdev list, otherwise we will only disable the timer if > > there is no monitor for all adapters. > > Agreed. Will fix it. > > > > >> + > >> +     hdev = hci_dev_get(index); > >> +     if (!hdev) { > >> +             err = -EINVAL; > >> +             goto out; > >> +     } > >> + > >> +     del_timer(&hdev->rssi_monitor_timer); > >> + > >> +     hci_dev_put(hdev); > >> + > >> +out: > >> +     write_unlock_bh(&rssi_monitor_list_lock); > >> +     return err; > >>  } > >> > >>  static int enable_rssi_monitor(struct sock *sk, u16 index, > >> @@ -1995,7 +2051,11 @@ static int rssi_monitor_send_alert(u16 index, bdaddr_t *bdaddr, s8 rssi) > >>       struct mgmt_ev_rssi_monitor_alert ev; > >>       u8 alert; > >> > >> +     read_lock(&rssi_monitor_list_lock); > >> + > >>       rm = rssi_monitor_find(index, bdaddr); > >> + > >> +     read_unlock(&rssi_monitor_list_lock); > >>       if (!rm) > >>               return -EINVAL; > >> > >> @@ -2718,3 +2778,22 @@ void mgmt_read_rssi_complete(u16 index, bdaddr_t *bdaddr, s8 rssi, u8 status) > >> > >>       rssi_monitor_send_alert(index, bdaddr, rssi); > >>  } > >> + > >> +void mgmt_do_read_rssi(struct hci_dev *hdev) > >> +{ > >> +     struct rssi_monitor *rm; > >> + > >> +     read_lock(&rssi_monitor_list_lock); > >> + > >> +     list_for_each_entry(rm, &rssi_monitor_list, list) { > >> + > >> +             if (rm->index != hdev->id) > >> +                     continue; > >> + > >> +             mgmt_read_rssi(hdev, &rm->bdaddr); > >> +     } > > > > Per adapter list could make this code better as well. > > The idea to keep this list only into Management module was to avoid > modifications in other part of bluetooth code since this RSSI > monitoring is expected to be implemented inside the controllers. But I > agree with you, if we have this list per adapter it could simplify the > code. What should I do? Move the list to hdev? Just add it to hdev. I also would like to move all the rssi timer logic to mgmt, to avoid some round trips between HCI and MGMT like hci_do_read_rssi -> mgmt_do_read_rssi -> hci_send_cmd. Also the setup_timer is in hci_core.c and mod_timer is mgmt.c. I'm still thinking on a good way to do this. Gustavo