From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: [PATCH] thread: do not attempt to join detached threads in pthread_join()
Date: Tue, 1 Aug 2017 18:56:02 -0400 [thread overview]
Message-ID: <20170801225602.GE1627@brightrain.aerifal.cx> (raw)
In-Reply-To: <20170801224613.9732-1-nenolod@dereferenced.org>
On Tue, Aug 01, 2017 at 10:46:13PM +0000, William Pitcock wrote:
> A thread which is detached releases it's resources and TCB upon thread termination.
> Therefore a thread which is detached is not joinable as any underlying futex will not
> be incremented, resulting in a deadlock. Accordingly, we return EINVAL instead of
> attempting to wait on a detached thread.
>
> Other pthread implementations such as glibc NPTL and FreeBSD also reject attempts
> to join detached threads with EINVAL.
Since the behavior is undefined and *can't be defined* in the general
case (where the detached thread may already have exited and its id may
even have been reused for a new thread), if any change is to be made,
the function should be made to crash in this case. Returning EINVAL
hides the (serious) programming error.
Rich
next prev parent reply other threads:[~2017-08-01 22:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-01 22:46 William Pitcock
2017-08-01 22:56 ` Rich Felker [this message]
2017-08-01 23:12 William Pitcock
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