On 01/27, Andrew Morton wrote: > > On Wed, 27 Jan 2016 17:41:54 +0100 Oleg Nesterov <[email protected]> wrote: > > > IOW, signal_pending() is the "special" condition, you do not need to > > serialize > > this check with task->state setting, exactly because schedule() knows about > > the > > signals. > > So it's non-buggy because signal_pending() is special. But it *looks* > buggy! And there's no comment there explaining why it looks buggy but > isn't, so someone may later come along and "fix" it for us.
perhaps we can add a comment somewhere in sched.h to explain that a task can never sleep with task->state == STATE if signal_pending_state(STATE) is true. Every user of signal_pending() in the wait-event-like loop relies on this well- known fact. Say, wait_event_interruptible() or __mutex_lock_common(). This is actually more about task->state, not about TIF_SIGPENDING imo. Oleg.
