Messages in this thread | | | Date | Tue, 27 Sep 2016 18:17:00 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v3] signals: Avoid unnecessary taking of sighand->siglock |
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On 09/27, Waiman Long wrote: > > +static inline int sigequalsets(const sigset_t *set1, const sigset_t *set2) > +{ > + switch (_NSIG_WORDS) { > + case 4: > + return (set1->sig[3] == set2->sig[3]) && > + (set1->sig[2] == set2->sig[2]) && > + (set1->sig[1] == set2->sig[1]) && > + (set1->sig[0] == set2->sig[0]); > + case 2: > + return (set1->sig[1] == set2->sig[1]) && > + (set1->sig[0] == set2->sig[0]); > + case 1: > + return set1->sig[0] == set2->sig[0]; > + } > + return 0; > +} > +
OK, this memcmp-by-hand matches other sig* helpers. Well, perhaps
default: BUILD_BUG();
makes sense too, but I won't insist.
> --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -2485,6 +2485,13 @@ void __set_current_blocked(const sigset_t *newset) > { > struct task_struct *tsk = current; > > + /* > + * In case the signal mask hasn't changed, there is nothing we need > + * to do. The current->blocked shouldn't be modified by other task. > + */ > + if (sigequalsets(&tsk->blocked, newset)) > + return; > +
Acked-by: Oleg Nesterov <oleg@redhat.com>
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