Return-Path: Sender: "Gustavo F. Padovan" Date: Mon, 11 Apr 2011 19:25:04 -0300 From: "Gustavo F. Padovan" To: Thomas Gleixner Cc: Marcel Holtmann , Vinicius Costa Gomes , Keith Packard , linux-kernel , linux-bluetooth@vger.kernel.org Subject: Re: 2.6.39-rc2 regression: X201s fails to resume b77dcf8460ae57d4eb9fd3633eb4f97b8fb20716 Message-ID: <20110411222504.GE2195@joana> References: <20110409000857.GB25581@piper> <1302558033.2572.219.camel@aeonflux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: List-ID: * Thomas Gleixner [2011-04-12 00:19:32 +0200]: > On Tue, 12 Apr 2011, Thomas Gleixner wrote: > > On Mon, 11 Apr 2011, Marcel Holtmann wrote: > > > > > Hi Thomas, > > > > > > > > > > Can the bluetooth folks please have a look at that ASAP? The obvious > > > > > > > fast fix for Linus tree is to revert the second hunk for now, but this > > > > > > > needs to be fixed proper. > > > > > > > > > > > > Who will submit this patch? I'd rather have your name on it so that > > > > > > people come complain at you... > > > > > > > > > > I took a shot at it and just sent a patch (also attached for convenience) > > > > > that should solve the problem. > > > > > > > > Aaarg. No. That patch reverts both hunks. > > > > > > > > --- a/net/bluetooth/hci_core.c > > > > +++ b/net/bluetooth/hci_core.c > > > > @@ -586,9 +586,6 @@ static int hci_dev_do_close(struct hci_dev *hdev) > > > > hci_req_cancel(hdev, ENODEV); > > > > hci_req_lock(hdev); > > > > > > > > - /* Stop timer, it might be running */ > > > > - del_timer_sync(&hdev->cmd_timer); > > > > - > > > > if (!test_and_clear_bit(HCI_UP, &hdev->flags)) { > > > > hci_req_unlock(hdev); > > > > return 0; > > > > > > > > As I said before you need that first hunk to stay for the case where > > > > there is no device up and you return via the !HCI_UP check. You just > > > > moved back to the state before as the stupid timer is active for > > > > whatever reason even when HCI_UP is not set. > > > > > > if I read this right then we have the case that we arm this timer for no > > > real reason. A device in !HCI_UP should have nothing running. Certainly > > > not the cmd_timer since it will never process any commands. > > > > > > According to Gustavo, the problem is really in the hci_reset logic were > > > we arm the timer even when shutting down the device. > > > > The reason why the original patch was sent is, that the timer was > > running when the thing went out via the !HCI_UP path, which caused the > > whole thing to explode in the first place. I had no time to figure out > > why, but moving the del_timer_sync above the > > if (!test_and_clear_bit(HCI_UP, &hdev->flags)) solved it. > > Oops. Hit send too fast. > > Then it broke the resume on Keith machine and reverting just the hunk > which disarms the timer in the > > if (hdev->sent_cmd) { > > path made both scenarios working. So there are two problems: > > 1) Why do we need the del_timer_sync() above the !HCI_UP check That is still a mysterious to me, the real bug the hiding here. I'm trying to track this down but no luck yet. > > 2) Why gets the timer rearmed after that It is armed at each HCI command we send. In the close path we send out an HCI RESET command that rearms it. -- Gustavo F. Padovan http://profusion.mobi