Return-Path: Date: Thu, 9 Jun 2011 16:09:52 -0700 (PDT) From: Mat Martineau To: "Gustavo F. Padovan" cc: linux-bluetooth@vger.kernel.org Subject: Re: [PATCH 2/4] Bluetooth: Rename _busy_wq to _l2cap_wq In-Reply-To: <20110609184747.GB2533@joana> Message-ID: References: <1307143270-2655-1-git-send-email-mathewm@codeaurora.org> <1307143270-2655-2-git-send-email-mathewm@codeaurora.org> <20110606173153.GA30641@joana> <20110609184747.GB2533@joana> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-bluetooth-owner@vger.kernel.org List-ID: On Thu, 9 Jun 2011, Gustavo F. Padovan wrote: > * Mat Martineau [2011-06-08 16:24:05 -0700]: > >> >> On Mon, 6 Jun 2011, Gustavo F. Padovan wrote: >> >>> * Mat Martineau [2011-06-03 16:21:08 -0700]: >>> >>>> This workqueue will be used for general L2CAP work, not just dealing >>>> with "busy" frames. >>> >>> which general L2CAP work are we talking about? >> >> I'll update the commit message and resubmit, but to immediately >> answer your question: >> >> * ERTM tx queue callbacks (patch 3/4 in this series) >> * ERTM timers (ack, retrans, monitor) that can utilize proper locking. > > What are the problems with ERTM timers? From what I remember it was not using > reference count on them, I fixed this. Patch is on this mailing for review. The ERTM timer handlers modify l2cap_chan data, but use bh_lock_sock() and bh_unlock_sock() instead of lock_sock() and release_sock(). The socket might be locked in userspace context, but these timers can fire and start executing code concurrently. See http://article.gmane.org/gmane.linux.bluez.kernel/6808 for the full description. With the refactoring of L2CAP to separate out the socket code, we will still need a per-channel lock to protect l2cap_chan data. >> * Updating the ERTM tx queue after an AMP channel move and L2CAP >> reconfiguration >> * Moving various AMP-related work out of interrupt context > > Marcel wrote a patch sometime ago the move the whole Bluetooth core work out > of the interrupt context. That will help with many issues we have today, > including these you are talking about. > We need to take that patch, fix it, and push it no bluetooth-next. > This task is on my TODO list, but my TODO list is getting bigger. ;) This would be a big help, do you have a pointer to this patch? Is the new workqueue accessible for all Bluetooth modules, or is it just for the HCI core? The other issues in my list still need a workqueue to use, they are not solved by moving rx processing out of interrupt context. If rx processing gets rid of interrupt context, we'll also want to take a close look at all other timer use. Thanks, -- Mat Martineau Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum