On Wed, Sep 22, 2010 at 08:53:49PM +0100, Al Viro wrote: > On Wed, Sep 22, 2010 at 12:08:53PM -0700, Linus Torvalds wrote: > > On Wed, Sep 22, 2010 at 11:53 AM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > > > > Um, no. ?You've *already* called get_signal_to_deliver(). ?There had been > > > no SIGSEGV in sight. ?You happily went on to set a sigframe for e.g. > > > SIGHUP, but ran out of stack. ?At that point you get force_sigsegv() > > > from handle_signal(). ?_NOW_ you have a pending SIGSEGV > > > > Ahh. Ok. Different case from the one I thought you were worried about. > > And yeah, I guess that one does require us to mess with the low-level > > asm code (although I do wonder if we could not make the whole > > do_notify_resume + reschedule code be generic C code - it's a lot of > > duplicated subtle asm as it is). > > Worse than just that... Note that on sparc you need to deal with > fault_in_user_windows(), which can also trigger signals. Actually, I wonder why don't we do the following: 1) check wsaved first, do fault_in_user_windows() if needed (and probably do Something Cruel(tm) if we fail copy_to_user() in there) 2) in a loop check if we need to reschedule / if we need to handle signals 3) don't bother with wsaved checks in setup_frame() variants at all - wsaved can't grow back at that point; we also can use flush_user_windows() instead of full synchronize_user_stack() in there. It's definitely a separate patch, but it looks like it might be worth doing... Comments? -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
