From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751103AbcGOM3t (ORCPT ); Fri, 15 Jul 2016 08:29:49 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:51758 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750881AbcGOM3q convert rfc822-to-8bit (ORCPT ); Fri, 15 Jul 2016 08:29:46 -0400 From: Arnd Bergmann To: Sebastian Andrzej Siewior Cc: linaro-kernel@lists.linaro.org, Build bot for Mark Brown , kernel-build-reports@lists.linaro.org, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Thomas Gleixner Subject: Re: v4.4.12-rt20 build: 0 failures 5 warnings (v4.4.12-rt20) Date: Fri, 15 Jul 2016 14:29:31 +0200 Message-ID: <2319169.Jp9upmpu5F@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-28-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <20160715120527.GB11606@linutronix.de> References: <4402302.GjsxlnvCX4@wuerfel> <20160715120527.GB11606@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K0:EDezSnYWGZz8UCqm7FB7xZqxLp+DCf2iwWq1NDk3Hp3lWMmq8nL HGnGsinFZxdL/qqLNM+bjJVD1WcHFKdaHudN8Pv+6/5TfojPAaWGvxajiz+FVeU3W/1B4ct 4gPdfsbBM/otD4LcN6gx/m1Bky37rqcW3Wo09/5R93UTfCjKamYKLp0CEyogLVwiksLXHxf MYGDic5gDEjjJTbyE6ZnA== X-UI-Out-Filterresults: notjunk:1;V01:K0:KDQs9ebuxy8=:X/zCXsUZ0RuVwn/4Em3mF6 0XculjZ4VPoTYe6H44REXdA5aHY/Qu3O5xmbP4DvALV5R9gTdbgR52oNUqti6oXK6TF0+c1Ju yE6fliV47jywKKo3MIC3LNNXASVEgX5mMQgmRCasqG/1cTo1KMtV+JfATL84T5Udu15yQVf2Y uaR3Yv07jMUWkGkYdCteczyQxtDzio8yiz4Q6lneWrQfbNaPPu8FP12jq3g0+FjKEjVbWmezh s0RYdDJqdnWQi6V3CT0pWZ1xJ19/vQElfEVqBaLpPs8fywuXj6it7Iu9/STPXxPwN6Cxx5sgM LrpLUiJXguzLN6F0PKlAzsofP5r+6dRCMAb1mBc89N5IUI/NG4kQ/qOY+iq6lQHgHC0UjKAsr R6mwAsCKShfTn8ITG9I/ejbLjqd6oZRtylYRO1kYwG5B4XORTHOBd21CFFVhvMvwttN8csFYK 3L1MlTZyQclEZdgFZQzxCF8MTealGBXWS8ja3vvIeqWgZH8YmJJu3EwUYVXE47vHwWc5tBRpl lt7cMWYwTvNlqFqTQKM6GYWo8JfLJRWoVSb6ogN3LHKdDKpQHjYr25kpnjr6iCKsNjRYSWN3m Da59//O0+vQmCRcG+ahCJMhSWToTL9e1pAprQ83Ky8gnhkTVgpR9iFNGCQA40leUsalgVLaFV EJzlxMLzEQd0zC1pEnbDbNLff21gJNh70QuSNk2SYvCuU9EFjrP8nsvuO4rTIMCfltwOuy7AJ AHonlhoxCm7DF7Xy Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, July 15, 2016 2:05:27 PM CEST Sebastian Andrzej Siewior wrote: > * Arnd Bergmann | 2016-07-15 09:07:20 [+0200]: > > >Cc linux-rt-users@vger.kernel.org, let's have a look at the individual warnings: > thanks. > > > > >> Warnings Summary: 5 > >> 9 ../kernel/sched/core.c:3473:12: warning: 'preemptible_lazy' defined but not used [-Wunused-function] > > > >This was introduced by the rt patchset, I'd suggest adding a fix to the next > >v4.4-rt release. This is almost certainly harmless. > > has been adressed in 4.6.4-rt8 and is harmless. Ok. > |drivers/tty/serial/amba-pl011.c: In function ‘pl011_console_write’: > |include/linux/spinlock.h:246:3: warning: ‘flags’ may be used uninitialized in this function [-Wmaybe-uninitialized] > | _raw_spin_unlock_irqrestore(lock, flags); \ > | ^ > |drivers/tty/serial/amba-pl011.c:2065:16: note: ‘flags’ was declared here > | unsigned long flags; > | ^ > > and relevant part of the source: > |pl011_console_write(struct console *co, const char *s, unsigned int count) > |{ > … > | unsigned long flags; > | int locked = 1; > | > … > | if (uap->port.sysrq) > | locked = 0; > | else if (oops_in_progress) > | locked = spin_trylock_irqsave(&uap->port.lock, flags); > | else > | spin_lock_irqsave(&uap->port.lock, flags); > … > | if (locked) > | spin_unlock_irqrestore(&uap->port.lock, flags); > … > |} > > looks like a false positive to me. Agreed, but it's hard for the compiler to figure that out. On mainline, we have this instead: local_irq_save(flags); if (uap->port.sysrq) locked = 0; else if (oops_in_progress) locked = spin_trylock(&uap->port.lock); else spin_lock(&uap->port.lock); … if (locked) spin_unlock(&uap->port.lock); local_irq_restore(flags); which looks like it's intentionally written to avoid the warning and was changed by Thomas in "tty/serial/pl011: Make the locking work on RT": http://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit/drivers/tty/serial/amba-pl011.c?h=v4.4-rt-rebase&id=7b537b66fcb12c40eb1b10eb352d570a9d34a657 Maybe there is another way to write this upstream that avoids the warning. Arnd