RE: force_sig_info

[Davide Libenzi <davidel@xmailserver.org>]

On Sun, 5 Sep 2004, Zach, Yoav wrote:

> >-----Original Message-----
> >From: Linus Torvalds [mailto:torvalds@osdl.org] 
> >Sent: Friday, September 03, 2004 21:12
> >To: Yoav Zach
> >Cc: akpm@osdl.org; linux-kernel@vger.kernel.org; Zach, Yoav
> >Subject: Re: force_sig_info
> >
> >
> >Why are you blocking signals that you want to get? Sounds like 
> >a bug in 
> >your program.
> 
> It's a translator - it emulates the behavior of the translated
> 'process', which is the one that sets the signal mask. On the
> other hand, it has its own logic, which requires handling of
> certain HW exceptions. In 2.4, signals that were raised due to
> HW exceptions could be handled by the translator regardless of
> the mask that was set by the translated process. We lost this
> ability in 2.6. It will be very good for our product, and I
> believe any similar product where a native process emulates 
> behavior of another process, if we could have this ability
> back.

Below is the latest patch I posted (applies on some Jun 2004 2.6.x) to 
bring 2.6 back to the 2.4 behaviour, but then it has been decided to leave 
2.6 as is.



- Davide




--- a/kernel/signal.c	2004-06-28 14:28:51.000000000 -0700
+++ b/kernel/signal.c	2004-06-28 14:29:31.000000000 -0700
@@ -820,8 +820,9 @@
 	int ret;
 
 	spin_lock_irqsave(&t->sighand->siglock, flags);
-	if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
+	if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
 		t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
+	if (sigismember(&t->blocked, sig)) {
 		sigdelset(&t->blocked, sig);
 		recalc_sigpending_tsk(t);
 	}