Hi Haijun, * haijun liu <liuhaijun.er@xxxxxxxxx> [2010-10-26 09:32:19 +0800]: > 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. I looked a bit into this and a good solution seems to be to hold a reference to the sock when we call a mod_timer() and then put the reference when we call del_timer() and the timer is inactive or when l2cap_monitor_timeout(). Look net/sctp/ for examples. -- Gustavo F. Padovan ProFUSION embedded systems - http://profusion.mobi -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
