From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1ACAEC43441 for ; Wed, 28 Nov 2018 21:00:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D3E2720832 for ; Wed, 28 Nov 2018 21:00:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D3E2720832 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726412AbeK2IDG (ORCPT ); Thu, 29 Nov 2018 03:03:06 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54660 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725996AbeK2IDG (ORCPT ); Thu, 29 Nov 2018 03:03:06 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0318230C583F; Wed, 28 Nov 2018 21:00:09 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-116-131.ams2.redhat.com [10.36.116.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2165819754; Wed, 28 Nov 2018 21:00:00 +0000 (UTC) From: Florian Weimer To: Christian Brauner Cc: ebiederm@xmission.com, linux-kernel@vger.kernel.org, serge@hallyn.com, jannh@google.com, luto@kernel.org, akpm@linux-foundation.org, oleg@redhat.com, cyphar@cyphar.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, dancol@google.com, timmurray@google.com, linux-man@vger.kernel.org Subject: Re: [PATCH] procfd_signal.2: document procfd_signal syscall References: <20181119103241.5229-1-christian@brauner.io> <20181119103241.5229-4-christian@brauner.io> Date: Wed, 28 Nov 2018 21:59:52 +0100 In-Reply-To: <20181119103241.5229-4-christian@brauner.io> (Christian Brauner's message of "Mon, 19 Nov 2018 11:32:40 +0100") Message-ID: <87in0g7waf.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 28 Nov 2018 21:00:10 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Christian Brauner: > +.\" Copyright (C) 2018 Christian Brauner The text seems to be largely derived from rt_sigqueueinfo, so I'm not sure if this appropriate here. > +the null signal (0) can be used to check if a process with a given > +PID exists. What does this mean if hte process is identified by file descriptor? > +.PP > +The optional > +.I info > +argument specifies the data to accompany the signal. > +This argument is a pointer to a structure of type > +.IR siginfo_t , > +described in > +.BR sigaction (2) > +(and defined by including > +.IR ). > +The caller should set the following fields in this structure: > +.TP > +.I si_code > +This must be one of the > +.B SI_* > +codes in the Linux kernel source file > +.IR include/asm-generic/siginfo.h , > +with the restriction that the code must be negative > +(i.e., cannot be > +.BR SI_USER , > +which is used by the kernel to indicate a signal sent by > +.BR kill (2)) > +and cannot (since Linux 2.6.39) be Obsolete reference in this context. > +.TP > +.B ESRCH > +The process or process group does not exist. > +Note that an existing process might be a zombie, > +a process that has terminated execution, but > +has not yet been > +.BR wait (2)ed > +for. Again: What does this mean if the process identified by a descriptor? Does a process in zombie state exist in this sense or not? Thanks, Florian