On Sun, 21 Dec 2014, vichy wrote: > >> Then I try to use msleep(100) but I found hub_port_status will first > >> mutex_lock(&hub->status_mutex); then calling get_port_status. > >> That mean the deadlock may happen. > > > > No it doesn't. > Why it doesn't? from the source, the get_port_status did called in > critical section protected by hub->status_mutex. > And msleep is not allowed in critical section. Yes it is. Why do you think it isn't? A critical section can be either atomic or non-atomic. If it is protected by a spinlock (or if it runs in an interrupt handler, or with interrupts or preemption disabled) then it is atomic, but if it is only protected by a mutex then it is non-atomic. msleep is not allowed in atomic sections, but it _is_ allowed in non-atomic sections. Even if the code is protected by a mutex. Alan Stern -- 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
