On Thu, 30 Nov 2006, Rafael J. Wysocki wrote: > > Here's what I mean. usb-storage's kernel thread is unfreezable, because > > it might be needed for reading or writing a memory image to a swap region. > > If there's an I/O error then usb-storage will try to issue a USB port > > reset, for which it needs to acquire the USB device's lock. > > > > Now various other tasks may acquire that lock, and they may even stop > > while holding it. However they should never get frozen while holding the > > lock -- which means they shouldn't get frozen at arbitrary times merely > > because they are stopped. They are careful to call try_to_freeze() only > > at times when they don't hold any locks. > > This means they are kernel threads, so they won't be entering > get_signal_to_deliver(), will they? Some of them are kernel threads and some of them are user threads. Only the kernel threads call try_to_freeze(). > If they don't enter get_signal_to_deliver(), they can only be frozen where > they explicitly call try_to_freeze(). What about the user threads? Alan Stern
