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Commit 73ef4aeb authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

signal: sigprocmask: narrow the scope of ->siglock 



No functional changes, preparation to simplify the review of the next change.

1. We can read current->block lockless, nobody else can ever change this mask.

2. Calculate the resulting sigset_t outside of ->siglock into the temporary
   variable, then take ->siglock and change ->blocked.

Also, kill the stale comment about BKL.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarMatt Fleming <matt.fleming@linux.intel.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
parent fec9993d

kernel/signal.c

+13 −16
Original line number Diff line number Diff line
@@ -2299,12 +2299,6 @@ long do_no_restart_syscall(struct restart_block *param) 
	return -EINTR;

}



/*

 * We don't need to get the kernel lock - this is all local to this

 * particular thread.. (and that's good, because this is _heavily_

 * used by various programs)

 */



/*

 * This is also useful for kernel threads that want to temporarily

 * (or permanently) block certain signals.
@@ -2315,30 +2309,33 @@ long do_no_restart_syscall(struct restart_block *param) 
 */

int sigprocmask(int how, sigset_t *set, sigset_t *oldset)

{

	int error;

	struct task_struct *tsk = current;

	sigset_t newset;



	spin_lock_irq(&current->sighand->siglock);

	/* Lockless, only current can change ->blocked, never from irq */

	if (oldset)

		*oldset = current->blocked;

		*oldset = tsk->blocked;



	error = 0;

	switch (how) {

	case SIG_BLOCK:

		sigorsets(&current->blocked, &current->blocked, set);

		sigorsets(&newset, &tsk->blocked, set);

		break;

	case SIG_UNBLOCK:

		signandsets(&current->blocked, &current->blocked, set);

		signandsets(&newset, &tsk->blocked, set);

		break;

	case SIG_SETMASK:

		current->blocked = *set;

		newset = *set;

		break;

	default:

		error = -EINVAL;

		return -EINVAL;

	}



	spin_lock_irq(&tsk->sighand->siglock);

	tsk->blocked = newset;

	recalc_sigpending();

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irq(&tsk->sighand->siglock);



	return error;

	return 0;

}



/**