From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752814AbaIHDRO (ORCPT ); Sun, 7 Sep 2014 23:17:14 -0400 Received: from mail-vc0-f178.google.com ([209.85.220.178]:36917 "EHLO mail-vc0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707AbaIHDRM (ORCPT ); Sun, 7 Sep 2014 23:17:12 -0400 MIME-Version: 1.0 In-Reply-To: <20140908012025.GF5061@mtj.dyndns.org> References: <20140908012025.GF5061@mtj.dyndns.org> Date: Sun, 7 Sep 2014 20:17:11 -0700 X-Google-Sender-Auth: 9gVIpvJ0SXxhoip7fHTyhVbkorw Message-ID: Subject: Re: [GIT PULL] cgroup fixes for v3.17-rc4 From: Linus Torvalds To: Tejun Heo Cc: Linux Kernel Mailing List , Li Zefan , cgroups@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 7, 2014 at 6:20 PM, Tejun Heo wrote: > > While this is a userland visible > behavior change, given the craziness of allowing '\n' and its > implications, I believe the change is justified. Tejun, absolutely nothing "justifies" things if they break. Not "bad design", not "craziness". Even security issues should be worked around without breaking, if at all possible, However, "userland visible" is only relevant _if_ things break. Presumably nobody actually uses '\n' in a cgroup name. And if nothing breaks, you don't need the excuses. In other words, I'll happily pull this, but your excuses for it are wrong-headed. There is no "crazyness justifies this". That's crap. But the argument of "nobody does this, so let's fix it before anybody _starts_ doing it" is perfectly valid - with the deep and implicit understanding that if it turns out somebody *does* do it, the change gets reverted asap. People need to understand this. "Theoretical ABI breakage" is entirely irrelevant. Nobody cares. But any _actual_ ABI breakage is a complete no-no. So next time you realize "ok, this could break things", don't make excuses. Look for alternatives (maybe the name can be escaped, for example), or take the approach of "let's hopw nobody notices". None of this "the interface is crazy, so we can change it". Because that is pure and utter BS. Whether the interface is crazy or not is *entirely* irrelevant to whether it can be changed or not. The only thing that matters is whether people actually _trigger_ the issue you have in reality, not whether the issue is crazy. See the difference? Linus From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [GIT PULL] cgroup fixes for v3.17-rc4 Date: Sun, 7 Sep 2014 20:17:11 -0700 Message-ID: References: <20140908012025.GF5061@mtj.dyndns.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=sBfV0d1lYoN+WNSEPK3zrX0GYa/Btaw2kJTpcwyhc0M=; b=rP8m055hQJ04ihktrLwIOaCCjsEtDt2D35OEBGF9EgpDzJ0tmamKvcP7demnMopMNy Bah0U1D1fBO5BL8ABXfglnooumcMYnBvMOQc7Ppl85ckjDbYL1ougGb1lzKP+K7p+d0h kZgWrAGi2Ttu6juCnmdDyVcSTsxmXExs9xwAhPYvjNfX1JwPFOR1kHQO/RFCN+OD88jZ DeCy6SrnE4yYpuerTN3syxM7BK/cYAHh0HL7VPGtazu63Wgx7RkyN+LIZAC52yWEDg6A 5sqq9h163WL/7wFTybWaJnETU6UP/XjlkxdLhpr6GB7cGRmm3fMpatvSOjLXyuFnIQB6 JumA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=sBfV0d1lYoN+WNSEPK3zrX0GYa/Btaw2kJTpcwyhc0M=; b=Tze68UBspxBxToCyDpIjVDRX6G53974Fhv8hUdQCmyBItrcYvfFpxM1LL7Jw3oMXOu WQJ1sMH0aVbyPTC7/Vx9xu8mTM1a8wXTNNRFgccEOSVtjfDMWY1GYn8q+2rhJLMx+QaS 6SZ/ee2VRtGf8I1eTbKZ6gwy8HziKXhQZGYu4= In-Reply-To: <20140908012025.GF5061-9pTldWuhBndy/B6EtB590w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tejun Heo Cc: Linux Kernel Mailing List , Li Zefan , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Sun, Sep 7, 2014 at 6:20 PM, Tejun Heo wrote: > > While this is a userland visible > behavior change, given the craziness of allowing '\n' and its > implications, I believe the change is justified. Tejun, absolutely nothing "justifies" things if they break. Not "bad design", not "craziness". Even security issues should be worked around without breaking, if at all possible, However, "userland visible" is only relevant _if_ things break. Presumably nobody actually uses '\n' in a cgroup name. And if nothing breaks, you don't need the excuses. In other words, I'll happily pull this, but your excuses for it are wrong-headed. There is no "crazyness justifies this". That's crap. But the argument of "nobody does this, so let's fix it before anybody _starts_ doing it" is perfectly valid - with the deep and implicit understanding that if it turns out somebody *does* do it, the change gets reverted asap. People need to understand this. "Theoretical ABI breakage" is entirely irrelevant. Nobody cares. But any _actual_ ABI breakage is a complete no-no. So next time you realize "ok, this could break things", don't make excuses. Look for alternatives (maybe the name can be escaped, for example), or take the approach of "let's hopw nobody notices". None of this "the interface is crazy, so we can change it". Because that is pure and utter BS. Whether the interface is crazy or not is *entirely* irrelevant to whether it can be changed or not. The only thing that matters is whether people actually _trigger_ the issue you have in reality, not whether the issue is crazy. See the difference? Linus