Return-Path: MIME-Version: 1.0 In-Reply-To: <20101025110131.GA7721@vigoh> References: <1287714419-13545-1-git-send-email-haijun.liu@atheros.com> <20101022171825.GA980@vigoh> <20101025110131.GA7721@vigoh> From: haijun liu Date: Tue, 26 Oct 2010 09:32:19 +0800 Message-ID: Subject: Re: [PATCH 1/2 v2] Bluetooth: Fix system crash caused by del_timer() To: "Gustavo F. Padovan" Cc: Haijun Liu , linux-bluetooth@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Gustavo, >> >> During test session with another vendor's bt stack, found that in >> >> l2cap_chan_del() using del_timer() caused l2cap_monitor_timeout() >> >> be called after the sock was freed, so it raised a system crash. >> >> So I just replaced del_timer() with del_timer_sync() to solve it. >> > >> > NAK on this. If you read the del_timer_sync() documentation you can >> > see that you can't call del_timer_sync() on interrupt context. The >> > possible solution here is to check in the beginning of >> > l2cap_monitor_timeout() if your sock is still valid. >> > >> >> You are right, I only considered close() interface, so missed the interrupt >> context. >> >> It's very difficult to check sock valid or not in timeout procedure, since it's >> an interrupt context, and only can get context from parameter pre-stored, >> except global variables. > > I think you can check for sk == null there. > It's a pre-stored parameter, it will not change by itself. -- Haijun Liu