From: David Laight <David.Laight@ACULAB.COM>
To: "'Dmitry V. Levin'" <ldv@altlinux.org>,
"David S. Miller" <davem@davemloft.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Alexey Gladkov <gladkov.alexey@gmail.com>,
Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>,
Anatoly Pugachev <matorola@gmail.com>,
"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] sparc: make copy_thread honor pid namespaces
Date: Thu, 18 Feb 2021 15:28:35 +0000 [thread overview]
Message-ID: <05247c8b0e31420a9e6e7a43831212ff@AcuMS.aculab.com> (raw)
In-Reply-To: <20210217080000.GA25861@altlinux.org>
From: Dmitry V. Levin
> Sent: 17 February 2021 08:00
>
> On sparc, fork and clone syscalls have an unusual semantics of
> returning the pid of the parent process to the child process.
Isn't that just broken?
The application expects fork() to return 0 in the child.
libc would have to do horrid things to convert the result.
It could be comparing against the saved 'current pid' in
order to save a system call for the first ppid() call.
But that isn't ever going to work if it is possible to
create a child in a different pid namespace.
FWIW the test program ought to use syscall() to get the pid
and ppid - rather than relying on any optimisations in libc.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2021-02-18 18:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 8:00 [PATCH] sparc: make copy_thread honor pid namespaces Dmitry V. Levin
2021-02-18 15:28 ` David Laight [this message]
2021-02-18 18:21 ` Eric W. Biederman
2021-02-19 22:50 ` [PATCH v2] " Dmitry V. Levin
2021-02-22 21:30 ` Eric W. Biederman
2021-02-23 11:14 ` Anatoly Pugachev
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