Return-Path: MIME-Version: 1.0 In-Reply-To: References: <1328588997-25029-1-git-send-email-aguedespe@gmail.com> <1328588997-25029-4-git-send-email-aguedespe@gmail.com> Date: Tue, 7 Feb 2012 13:20:09 -0200 Message-ID: Subject: Re: [PATCH 3/3] Bluetooth: Use advertising cache thread-safe functions From: Ulisses Furquim To: Andre Guedes Cc: Anderson Lizardo , Andre Guedes , linux-bluetooth@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Andre, On Tue, Feb 7, 2012 at 12:46 PM, Andre Guedes wrote: > Hi Ulisses, > > On Tue, Feb 7, 2012 at 10:26 AM, Ulisses Furquim wrote: >> Hi Andre, >> >> On Tue, Feb 7, 2012 at 10:20 AM, Andre Guedes >> wrote: >>> Hi Lizardo, >>> >>> On Tue, Feb 7, 2012 at 7:48 AM, Anderson Lizardo >>> wrote: >>>> Hi Andre, >>>> >>>> On Tue, Feb 7, 2012 at 12:29 AM, Andre Guedes wrote: >>>>> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c >>>>> index 6808069..3933ccd 100644 >>>>> --- a/net/bluetooth/hci_event.c >>>>> +++ b/net/bluetooth/hci_event.c >>>>> @@ -3255,12 +3255,10 @@ static inline void hci_le_adv_report_evt(struct hci_dev *hdev, >>>>> ? ? ? ?void *ptr = &skb->data[1]; >>>>> ? ? ? ?s8 rssi; >>>>> >>>>> - ? ? ? hci_dev_lock(hdev); >>>>> - >>>> >>>> So there is no need to lock hdev between the hci_add_adv_entry() and >>>> mgmt_device_found() calls? This looks different from what is done for >>>> BR/EDR for the inquiry cache. >>> >>> Yes, mgmt_device_found() does not require locking hdev->lock. >> >> We could then move the lock and unlock calls to inside the loop. But >> as we might have more than one call to hci_add_adv_entry() it'd be >> good to lock and unlock only once, no? Any problems I don't see? > > Yes, that's right. For this particular case, it may be better to lock > hdev outside while() and call the thread-unsafe version here. > > This way, it may be better we just drop patches 02/03 and 03/03. > >>>>> ? ? ? ?while (num_reports--) { >>>>> ? ? ? ? ? ? ? ?struct hci_ev_le_advertising_info *ev = ptr; >>>>> >>>>> - ? ? ? ? ? ? ? __hci_add_adv_entry(hdev, ev); >>>>> + ? ? ? ? ? ? ? hci_add_adv_entry(hdev, ev); >>>>> >>>>> ? ? ? ? ? ? ? ?rssi = ev->data[ev->length]; >>>>> ? ? ? ? ? ? ? ?mgmt_device_found(hdev, &ev->bdaddr, LE_LINK, ev->bdaddr_type, >>>>> @@ -3268,8 +3266,6 @@ static inline void hci_le_adv_report_evt(struct hci_dev *hdev, >>>>> >>>>> ? ? ? ? ? ? ? ?ptr += sizeof(*ev) + ev->length + 1; >>>>> ? ? ? ?} >>>>> - >>>>> - ? ? ? hci_dev_unlock(hdev); >>>>> ?} >>>>> >>>>> ?static inline void hci_le_ltk_request_evt(struct hci_dev *hdev, >>>>> -- >>>>> 1.7.9 >> >> While I don't see anything wrong with your changes I don't think we >> really need it. All the other functions that need to be called with >> hdev->lock held don't have "__" prefix so it'll be different than the >> others. And you added 3 new locked functions but your last patch only >> uses 2 of them and only in 2 places. Unless I'm missing something here >> we don't really need this refactoring at all. Do you have any other >> reason to do that? Are you gonna use those functions in other >> patchset? > > Yes, some other functions don't have the prefix "__" and that fact > makes a bit painful and error-prone since we always have to dig in > the "call chain" to know if we need to hold hdev->lock or not. > Prefixing a function with "__" is just a standard way to indicate > that. I understand that. I just don't know if Marcel will want to change them all to have "__" prefixes, though. Having only one subset with this prefix can make things even more confusing, don't you agree? And have you been working with these functions or is this just a cleanup you thought it'd be good to do? Regards, -- Ulisses Furquim ProFUSION embedded systems http://profusion.mobi Mobile: +55 19 9250 0942 Skype: ulissesffs