Hi, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes: > On Fri, 2 Sep 2016, Felipe Balbi wrote: > >> >> Hi, >> >> Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes: >> >> [...] >> >> > No, that would be too late. The barrier needs to go between the write >> > to common->thead_wakeup_needed and the call to wake_up_process(). >> >> alright, I tested this but it doesn't work. It still hangs :-( > > Okay, I was wrong. But see my recent reply to Paul; maybe the > smp_wmb() in wakeup_thread() needs to be smp_mb(). okay, this seems to be working so far: modified drivers/usb/gadget/function/f_mass_storage.c @@ -395,7 +395,7 @@ static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep) /* Caller must hold fsg->lock */ static void wakeup_thread(struct fsg_common *common) { - smp_wmb(); /* ensure the write of bh->state is complete */ + smp_mb(); /* ensure the write of bh->state is complete */ /* Tell the main thread that something has happened */ common->thread_wakeup_needed = 1; if (common->thread_task) @@ -626,7 +626,7 @@ static int sleep_thread(struct fsg_common *common, bool can_freeze) } __set_current_state(TASK_RUNNING); common->thread_wakeup_needed = 0; - smp_rmb(); /* ensure the latest bh->state is visible */ + smp_mb(); /* ensure the latest bh->state is visible */ return rc; } I'll keep it running over the weekend. thanks -- balbi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html