From: Oleg Nesterov <oleg@tv-sign.ru>
To: Roland McGrath <roland@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sigwait eats blocked default-ignore signals
Date: Wed, 14 Nov 2007 18:53:00 +0300 [thread overview]
Message-ID: <20071114155300.GA12407@tv-sign.ru> (raw)
In-Reply-To: <20071114073249.CEECC26F8B6@magilla.localdomain>
On 11/13, Roland McGrath wrote:
>
> > But I suspect we have other issues here. Let's suppose we have threads T1
> > (main) and T2. T2 blocks SIGCHLD and does sigwait(SIGCHLD).
> >
> > Now, we send SIGCHLD to the thread group. The signal is lost again because
> > sig_ignored() returns true on T1's side.
> >
> > Is this OK? [...]
>
> Yes, it's OK if T1 has SIGCHLD unblocked. When there are multiple threads
> that either don't block the signal or are in sigwait for it, then it can go
> to any of them and there are no guarantees at all about which. So we
> simply say that the signal went to the thread not in sigwait that has that
> signal unblocked (T1). When it got there, it was ignored. The user
> semantics are equivalent even if that thread never actually woke and
> dequeued the signal to ignore it.
Yes.
I misunderstood the required semantics for sigwait(), thanks Roland.
Oleg.
prev parent reply other threads:[~2007-11-14 15:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-12 23:41 Roland McGrath
2007-11-13 15:56 ` Oleg Nesterov
2007-11-13 23:32 ` Roland McGrath
2007-11-14 15:53 ` Oleg Nesterov [this message]
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