On Mon, Sep 22, 2014 at 06:44:37PM +0200, Oleg Nesterov wrote: > __lock_task_sighand() does local_irq_save() to prevent the potential > deadlock, we can use preempt_disable() with the same effect. And in > this case we can do preempt_disable/enable + rcu_read_lock/unlock only > once outside of the main loop and simplify the code. This also shaves > 112 bytes from signal.o. > > With this patch the main loop runs with preemption disabled, but this > should be fine because restart is very unlikely: it can only happen if > we race with de_thread() and ->sighand is shared. And the latter is only > possible if CLONE_SIGHAND was used without CLONE_THREAD, most probably > nobody does this nowadays.
If its unlikely to repeat, it shouldn't matter either way and we can keep the preempt_disable() inside the loop to guarantee better worst case behaviour. And I suppose we can fix -rt, like Steve already mentioned, there's the preempt_disable_nort() thing for just such cases. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
