| Date | Tue, 16 Aug 2011 18:49:28 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 18/41] OpenRISC: Don't reimplement force_sigsegv() |
| |
On 08/11, Matt Fleming wrote: > > Instead of open coding the sequence from force_sigsegv() just call > it. This also fixes a race because sa_handler was being modified > without holding ->sighand->siglock. > > --- a/arch/openrisc/kernel/signal.c > +++ b/arch/openrisc/kernel/signal.c > @@ -257,9 +257,7 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, > return; > > give_sigsegv: > - if (sig == SIGSEGV) > - ka->sa.sa_handler = SIG_DFL; > - force_sig(SIGSEGV, current); > + force_sigsegv(sig, current); > }
Agreed, but...
I don't really understand the changelog, which race this patch fix?
Yes, we shouldn't change sa_handler lockless, this "breaks the rules" but I do not see any immediate problem. And since force_sigsegv() drops the lock after setting SIG_DFL we can "race" with the sub-thread anyway.
Hmm. Looking more, I think that this patch is not the cleanup, but the bugfix. The current code is simply wrong, it plays with ka, and it points to the _copy_ of sighand->action[], so this code is simply pointless.
Unless I missed something, could you fix the changelog and resend?
Oleg.
|