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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 556ECC282E2 for ; Sat, 20 Apr 2019 19:04:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26E7E20833 for ; Sat, 20 Apr 2019 19:04:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="QpK1Wuo2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727516AbfDTTEu (ORCPT ); Sat, 20 Apr 2019 15:04:50 -0400 Received: from mail.skyhub.de ([5.9.137.197]:48406 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726309AbfDTTEt (ORCPT ); Sat, 20 Apr 2019 15:04:49 -0400 Received: from zn.tnic (p200300EC2F112E00E1C548496DF7C17A.dip0.t-ipconnect.de [IPv6:2003:ec:2f11:2e00:e1c5:4849:6df7:c17a]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id CE5071EC014A; Sat, 20 Apr 2019 21:04:46 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1555787086; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=ShvJsdhScM7s7cbfAJAGtm4jgWtD1rQ7Rc7XC1MIgWo=; b=QpK1Wuo2uTC3kJRxsiJu5fojgPmk+cnYUnGh22mvEtMlYq31b7TJgVF2ANm2c4euIBYI9q YLSYPjpNI5S7kaqIxc15OM7IPVNgbsPSghvI7cjcyJlS2cnlSb1jyHDDL5egH4jER1yGbz zLHx11KwI36yUYgLBIH5/kKffCNLCK0= Date: Sat, 20 Apr 2019 21:04:42 +0200 From: Borislav Petkov To: Cong Wang Cc: LKML , linux-edac@vger.kernel.org, Tony Luck , Thomas Gleixner Subject: Re: [PATCH v2 1/2] ras: fix an off-by-one error in __find_elem() Message-ID: <20190420190442.GF29704@zn.tnic> References: <20190416213351.28999-1-xiyou.wangcong@gmail.com> <20190416214634.GP31772@zn.tnic> <20190420113444.GC29704@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 20, 2019 at 11:25:43AM -0700, Cong Wang wrote: > If you want to go that far, you can choose to use lib/bsearch.c too in > case you want to reinvent the wheel. Well, that doesn't give me the @to functionality which points to the slot where the new element should be inserted, when the search was unsuccessful. > What's your point here? My point is to fix it properly. Obviously. > You know my fix is targeted for -stable, Well, first you sent me this: https://lkml.kernel.org/r/20190416012001.5338-1-xiyou.wangcong@gmail.com then this: https://lkml.kernel.org/r/20190416213351.28999-1-xiyou.wangcong@gmail.com Tony liked this second version more and if you look at the final result of mine: int min = 0, max = ca->n - 1; ... if (this_pfn < pfn) min = i + 1; else if (this_pfn > pfn) max = i - 1; else if (this_pfn == pfn) { if (to) *to = i; return i; } it has basically *both*: the correct [min:max] range *and* the return of ithe ndex when found. But the algorithm this time is the correct one. > I doubt your 83-line change could fit for -stable. My 83-line change has debug output only for experimentation. It will, *of* *course* be removed before committing it upstream. That's why I called it "a conglomerate patch" and I said "It has some debug output for easier debugging, that will be removed in the final version, of course." I guess you didn't read that either. And the sanity_check() piece will be a separate patch, of course. In the end the diffstat will be 30-40 lines max. > Feel free to drop my patch to favor yours. I am really tired. Suit yourself. Thanks for the reporting. > Good luck with that! Ditto. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply. From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [v2,1/2] ras: fix an off-by-one error in __find_elem() From: Borislav Petkov Message-Id: <20190420190442.GF29704@zn.tnic> Date: Sat, 20 Apr 2019 21:04:42 +0200 To: Cong Wang Cc: LKML , linux-edac@vger.kernel.org, Tony Luck , Thomas Gleixner List-ID: T24gU2F0LCBBcHIgMjAsIDIwMTkgYXQgMTE6MjU6NDNBTSAtMDcwMCwgQ29uZyBXYW5nIHdyb3Rl Ogo+IElmIHlvdSB3YW50IHRvIGdvIHRoYXQgZmFyLCB5b3UgY2FuIGNob29zZSB0byB1c2UgbGli L2JzZWFyY2guYyB0b28gaW4KPiBjYXNlIHlvdSB3YW50IHRvIHJlaW52ZW50IHRoZSB3aGVlbC4K CldlbGwsIHRoYXQgZG9lc24ndCBnaXZlIG1lIHRoZSBAdG8gZnVuY3Rpb25hbGl0eSB3aGljaCBw b2ludHMgdG8gdGhlCnNsb3Qgd2hlcmUgdGhlIG5ldyBlbGVtZW50IHNob3VsZCBiZSBpbnNlcnRl ZCwgd2hlbiB0aGUgc2VhcmNoIHdhcwp1bnN1Y2Nlc3NmdWwuCgo+IFdoYXQncyB5b3VyIHBvaW50 IGhlcmU/CgpNeSBwb2ludCBpcyB0byBmaXggaXQgcHJvcGVybHkuIE9idmlvdXNseS4KCj4gWW91 IGtub3cgbXkgZml4IGlzIHRhcmdldGVkIGZvciAtc3RhYmxlLAoKV2VsbCwgZmlyc3QgeW91IHNl bnQgbWUgdGhpczoKCmh0dHBzOi8vbGttbC5rZXJuZWwub3JnL3IvMjAxOTA0MTYwMTIwMDEuNTMz OC0xLXhpeW91Lndhbmdjb25nQGdtYWlsLmNvbQoKdGhlbiB0aGlzOgoKaHR0cHM6Ly9sa21sLmtl cm5lbC5vcmcvci8yMDE5MDQxNjIxMzM1MS4yODk5OS0xLXhpeW91Lndhbmdjb25nQGdtYWlsLmNv bQoKVG9ueSBsaWtlZCB0aGlzIHNlY29uZCB2ZXJzaW9uIG1vcmUgYW5kIGlmIHlvdSBsb29rIGF0 IHRoZSBmaW5hbCByZXN1bHQgb2YgbWluZToKCglpbnQgbWluID0gMCwgbWF4ID0gY2EtPm4gLSAx OwoKCS4uLgoKICAgICAgICAgICAgICAgIGlmICh0aGlzX3BmbiA8IHBmbikKICAgICAgICAgICAg ICAgICAgICAgICAgbWluID0gaSArIDE7CiAgICAgICAgICAgICAgICBlbHNlIGlmICh0aGlzX3Bm biA+IHBmbikKICAgICAgICAgICAgICAgICAgICAgICAgbWF4ID0gaSAtIDE7CiAgICAgICAgICAg ICAgICBlbHNlIGlmICh0aGlzX3BmbiA9PSBwZm4pIHsKICAgICAgICAgICAgICAgICAgICAgICAg aWYgKHRvKQogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICp0byA9IGk7CiAgICAgICAg ICAgICAgICAgICAgICAgIHJldHVybiBpOwogICAgICAgICAgICAgICAgfQoKaXQgaGFzIGJhc2lj YWxseSAqYm90aCo6IHRoZSBjb3JyZWN0IFttaW46bWF4XSByYW5nZSAqYW5kKiB0aGUgcmV0dXJu IG9mCml0aGUgbmRleCB3aGVuIGZvdW5kLiBCdXQgdGhlIGFsZ29yaXRobSB0aGlzIHRpbWUgaXMg dGhlIGNvcnJlY3Qgb25lLgoKPiBJIGRvdWJ0IHlvdXIgODMtbGluZSBjaGFuZ2UgY291bGQgZml0 IGZvciAtc3RhYmxlLgoKTXkgODMtbGluZSBjaGFuZ2UgaGFzIGRlYnVnIG91dHB1dCBvbmx5IGZv ciBleHBlcmltZW50YXRpb24uIEl0IHdpbGwsCipvZiogKmNvdXJzZSogYmUgcmVtb3ZlZCBiZWZv cmUgY29tbWl0dGluZyBpdCB1cHN0cmVhbS4gVGhhdCdzIHdoeSBJCmNhbGxlZCBpdCAiYSBjb25n bG9tZXJhdGUgcGF0Y2giIGFuZCBJIHNhaWQgIkl0IGhhcyBzb21lIGRlYnVnIG91dHB1dApmb3Ig ZWFzaWVyIGRlYnVnZ2luZywgdGhhdCB3aWxsIGJlIHJlbW92ZWQgaW4gdGhlIGZpbmFsIHZlcnNp b24sIG9mCmNvdXJzZS4iIEkgZ3Vlc3MgeW91IGRpZG4ndCByZWFkIHRoYXQgZWl0aGVyLgoKQW5k IHRoZSBzYW5pdHlfY2hlY2soKSBwaWVjZSB3aWxsIGJlIGEgc2VwYXJhdGUgcGF0Y2gsIG9mIGNv dXJzZS4KCkluIHRoZSBlbmQgdGhlIGRpZmZzdGF0IHdpbGwgYmUgMzAtNDAgbGluZXMgbWF4LgoK PiBGZWVsIGZyZWUgdG8gZHJvcCBteSBwYXRjaCB0byBmYXZvciB5b3Vycy4gSSBhbSByZWFsbHkg dGlyZWQuCgpTdWl0IHlvdXJzZWxmLiBUaGFua3MgZm9yIHRoZSByZXBvcnRpbmcuCgo+IEdvb2Qg bHVjayB3aXRoIHRoYXQhCgpEaXR0by4K