On Wed, Aug 21, 2019 at 03:31:39PM +0200, Thomas Gleixner wrote: > On Wed, 21 Aug 2019, Frederic Weisbecker wrote: > > So I propose to change the behaviour of case 1) so that $TARGET doesn't call > > posix_cpu_timers_exit(). We instead wait for $OWNER to exit and call > > exit_itimers() -> timer_delete_hook($ITIMER) -> > > posix_cpu_timer_del($ITIMER). > > It is going to find $TARGET as the target of $ITIMER but no more sighand. > > Then > > finally it removes $ITIMER from $TARGET->cputime_expires. > > We basically do the same thing as in 2) but without locking sighand since > > it's NULL > > on $TARGET at this time. > > But what do we win with that? Horrors like this: > > task A task B task C > > arm_timer(A) arm_timer(A) > > do_exit() > > del_timer(A) del_timer(A) > no sighand no_sighand > list_del() list_del() > > Guess how well concurrent list deletion works. > > We must remove armed timers from the task/signal _before_ dropping sighand, > really.
Ah right, there can be concurrent owners, nevermind.
