From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.3 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 10682 invoked from network); 15 Oct 2020 08:50:42 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with ESMTPUTF8; 15 Oct 2020 08:50:42 -0000 Received: (qmail 24272 invoked by uid 550); 15 Oct 2020 08:50:37 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 24254 invoked from network); 15 Oct 2020 08:50:36 -0000 Date: Thu, 15 Oct 2020 10:50:24 +0200 From: Szabolcs Nagy To: Alexey Izbyshev Cc: musl@lists.openwall.com Message-ID: <20201015085024.GR2947641@port70.net> Mail-Followup-To: Alexey Izbyshev , musl@lists.openwall.com References: <948f6fc6f3458f18152c0f8b505beec0@ispras.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <948f6fc6f3458f18152c0f8b505beec0@ispras.ru> Subject: Re: [musl] Why is setrlimit() considered to have per-thread effect? * Alexey Izbyshev [2020-10-15 08:01:00 +0300]: > Commit 544ee752cd[1] claims that setrlimit() is per-thread on Linux, > similarly to setxid() calls, so it should be called via __synccall(). But > this appears to be wrong: the kernel code operates on tsk->signal[2], which > is a per-thread-group structure. Glibc doesn't call setrlimit() for each > thread either. Am I missing something? note that prlimit does not have synccall in musl: the kernel implemented the per process rlimit setting when prlimit was added. (i think this is linux commit 1c1e618ddd15f69fd87ccea596769f78c8065504 ) but older kernels don't have that. > > Tangentially, setgroups() is not called via __synccall(), though it does > have per-thread effect. Is this intentional? that may be a bug, but it's not a posix api so not a conformance issue, but a linux issue: if other linux libcs don't do synccall then that's the defacto interface contract. > > Alexey > > [1] https://git.musl-libc.org/cgit/musl/commit/?id=544ee752cd38febfa3aa3798b4dfb6fabd13846b > [2] https://elixir.bootlin.com/linux/v5.9/source/kernel/sys.c#L1566