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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55526CA0FF0 for ; Fri, 1 Sep 2023 18:16:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242415AbjIASQv (ORCPT ); Fri, 1 Sep 2023 14:16:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233132AbjIASQu (ORCPT ); Fri, 1 Sep 2023 14:16:50 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2A10F2 for ; Fri, 1 Sep 2023 11:16:47 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 93957211CE; Fri, 1 Sep 2023 18:16:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1693592206; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SczNKaVL1iGLO0+CrAmVKlavPYKq/W/vUS1YtqrLUeA=; b=NS3n//SRONg/+5qwYUhU4v7EUfrYcHS6eBYWOfvhso+oKNwFKksOfTgCDTeUIwMwHBARnp h1kOIlxIZBBWNKUMr0xYYqdxJc0gMN5wN9x/5STfYZ9uxO/yoUn9xrkqTnz3rJBHn4KAsg j+mh+pMUG2KR/j5O0vh0nWMcsmSYzwM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1693592206; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SczNKaVL1iGLO0+CrAmVKlavPYKq/W/vUS1YtqrLUeA=; b=fMrgFtVvLdrPEqKIjJoDzcyLZuWrTbedHnbRrE/d58/WtNZWw5CYV+ftwQ2YFYm7xjUrAR N+pdmTTHgDR6UnCw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 77D1B13582; Fri, 1 Sep 2023 18:16:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id +z3/G44q8mQ5SwAAMHmgww (envelope-from ); Fri, 01 Sep 2023 18:16:46 +0000 Date: Fri, 1 Sep 2023 20:17:22 +0200 From: Cyril Hrubis To: Petr Vorel Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , linux-kernel@vger.kernel.org, ltp@lists.linux.it Subject: Re: [LTP] [PATCH] sched/rt: Disallow writing invalid values to sched_rt_period_us Message-ID: References: <20230901154355.5351-1-chrubis@suse.cz> <20230901174529.GB364687@pevik> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230901174529.GB364687@pevik> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > Documentation/scheduller/sched-rt-group.rst [1] specifies this as values from -1 to > (INT_MAX - 1), I guess due int range. Looking into proc_dointvec_minmax() [2] > even INT_MAX would pass the check. I suppose we can do nothing about that, > because there is no value in sysctl_vals[] which would represent INT_MAX - 1. > > And you specify in LTP test range: from -1 to INT_MAX. > > But even much shorter value than INT_MAX fails: > > $ echo 1234567 > /proc/sys/kernel/sched_rt_runtime_us > sh: echo: write error: Invalid argument That is because runtime_us must be < period_us by definition, since runtime_us defines how much time is allocated from the period_us. I guess that this is not described good enough in the kernel docs. -- Cyril Hrubis chrubis@suse.cz