Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751831AbaKGJ5z (ORCPT ); Fri, 7 Nov 2014 04:57:55 -0500 Received: from mail-wi0-f182.google.com ([209.85.212.182]:50613 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750957AbaKGJ5v (ORCPT ); Fri, 7 Nov 2014 04:57:51 -0500 Message-ID: <545C9791.7050608@linaro.org> Date: Fri, 07 Nov 2014 09:57:37 +0000 From: Daniel Thompson User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Joe Perches CC: Jason Wessel , linux-kernel@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, Andrew Morton , Ingo Molnar , patches@linaro.org, linaro-kernel@lists.linaro.org, John Stultz , Sumit Semwal Subject: Re: [RESEND PATCH 3.18-rc3] kdb: Avoid printing KERN_ levels to consoles References: <1411555097-16924-1-git-send-email-daniel.thompson@linaro.org> <1415287626-25802-1-git-send-email-daniel.thompson@linaro.org> <1415290399.6634.52.camel@perches.com> <545BAE67.1060602@linaro.org> <1415295835.6634.56.camel@perches.com> In-Reply-To: <1415295835.6634.56.camel@perches.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/11/14 17:43, Joe Perches wrote: > On Thu, 2014-11-06 at 17:22 +0000, Daniel Thompson wrote: >> On 06/11/14 16:13, Joe Perches wrote: >>> On Thu, 2014-11-06 at 15:27 +0000, Daniel Thompson wrote: >>>> Currently when kdb traps printk messages then the raw log level prefix >>>> (consisting of '\001' followed by a numeral) does not get stripped off >>>> before the message is issued to the various I/O handlers supported by >>>> kdb. This causes annoying visual noise as well as causing problems >>>> grepping for ^. It is also a change of behaviour compared to normal usage >>>> of printk() usage. For example -h ends up with different to that of >>>> kdb's "sr h". >>>> >>>> This patch addresses the problem by stripping log levels from messages >>>> before they are issued to the I/O handlers. >>> >>> Perhaps instead of stripping the logging level, >>> maybe a KERN_SOH_ASCII 'char' sequence should be >>> emitted as '<' 'char' '>' (see: printk:print_prefix) >>> >>> Maybe this should be added to stable from v3.6 >>> when KERN_SOH_ASCII was first added. >> >> You mean call the problem a regression and try to restore the original >> 3.5 behaviour? > > Yes. > > I added KERN_SOH_ASCII so to me it's a regression. > >> However I have to confess that I don't really like the old behaviour. >> I'd view it as contradicting the normal behaviours of consoles >> (including the kgdbcon console). Why should printk() inside kdb show >> different text to printk() outside kdb? For me, having <5> and >> scribbled all over the output of an "sr" command (which I think is >> probably the heaviest user of printk() inside kdb) never struck me as >> adding much value. >> >> Is the above paragraph convincing? > > I don't use it so I have a useful opinion. > > I don't recall that anyone has reported it in the > 2+ years since so it doesn't seem widely used. Does that arguing against Cc:ing stable@ or you think I should just put that on anyway and leave it for the stable committee? > But then again, this is a resend and I don't recall > seeing it the first time either. > >> On the other hand if you really mean "perhaps and maybe" then I'd prefer >> to leave it as it it. > > Your choice. > > btw: in the patch I suggest using printk_skip_level > instead of the direct test here: > > + cp = kdb_buffer; > + if (cp[0] == KERN_SOH_ASCII && cp[1] != '\0') > + cp += 2; > > so this could be > > cp = printk_skip_level(kdb_buffer); Excellent. I'll do that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/