On Sun, Oct 23, 2005 at 02:56:14PM +0400, Oleg Nesterov wrote:
> "Paul E. McKenney" wrote:
> >
> > Hello!
> >
> > The following patch combines a bit of redundant code between
> > force_sig_info() and force_sig_specific(). Tested on x86 and ppc64.
>
> Some minor nitpicks ...
>
> > +++ linux-2.6.14-rc2-rt7-force_sig/kernel/signal.c 2005-09-29 18:41:07.000000000 -0700
> > @@ -920,8 +920,8 @@ force_sig_info(int sig, struct siginfo *
> > if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
> > t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
> > sigdelset(&t->blocked, sig);
>
> May be it would be more readable to do:
>
> if (handler == SIG_IGN)
> handler = SIG_DFL;
>
> if (sigismember(->blocked, sig)) // probably unneeded at all
> sigdelset(->blocked, sig);
Seems reasonable to me.
> > - recalc_sigpending_tsk(t);
> > }
> > + recalc_sigpending_tsk(t);
>
> I never understood why can't we just do:
>
> set_tsk_thread_flag(TIF_SIGPENDING);
>
> If this signal is not pending yet specific_send_siginfo() will
> set this flag anyway.
My guess is that putting the general logic into recalc_sigpending_tsk()
prevents some bugs that might otherwise show up if someone forgets one
of the conditions that can result in a signal being asserted. But in
this case, it seems pretty safe. We really do want to force a signal.
But it is a minor optimization, so I left it as is for now.
> > - specific_send_sig_info(sig, (void *)2, t);
> > - spin_unlock_irqrestore(&t->sighand->siglock, flags);
> > + force_sig_info(sig, (void *)2, t);
>
> Paul, if you think this patch should go into the -mm tree first,
> could you rediff this patch against -mm ?
>
> - specific_send_sig_info(sig, SEND_SIG_FORCED, t);
> + force_sig_info(sig, SEND_SIG_FORCED, t);
Some time in -mm would certainly not hurt. The patch below is against
2.6.14-rc4-mm1, though Andrew asks that they be against a recent Linus
tree (see 5c in http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt).
In any case, "SEND_SIG_FORCED" seems much nicer than "(void *)2". ;-)
Thanx, Paul
diff -urpNa -X dontdiff linux-2.6.14-rc4-mm1/kernel/signal.c linux-2.6.14-rc4-mm1-force-sig/kernel/signal.c
--- linux-2.6.14-rc4-mm1/kernel/signal.c 2005-10-23 07:47:05.000000000 -0700
+++ linux-2.6.14-rc4-mm1-force-sig/kernel/signal.c 2005-10-23 08:01:16.000000000 -0700
@@ -889,11 +889,13 @@ force_sig_info(int sig, struct siginfo *
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);
}
+ recalc_sigpending_tsk(t);
ret = specific_send_sig_info(sig, info, t);
spin_unlock_irqrestore(&t->sighand->siglock, flags);
@@ -903,15 +905,7 @@ force_sig_info(int sig, struct siginfo *
void
force_sig_specific(int sig, struct task_struct *t)
{
- unsigned long int flags;
-
- spin_lock_irqsave(&t->sighand->siglock, flags);
- if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
- t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
- sigdelset(&t->blocked, sig);
- recalc_sigpending_tsk(t);
- specific_send_sig_info(sig, SEND_SIG_FORCED, t);
- spin_unlock_irqrestore(&t->sighand->siglock, flags);
+ force_sig_info(sig, SEND_SIG_FORCED, t);
}
/*
-
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