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[2a01:7a0:2:106d:700::1]) by mx.google.com with ESMTPS id h8si306240wrr.91.2019.04.18.14.14.55 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Thu, 18 Apr 2019 14:14:56 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a01:7a0:2:106d:700::1 as permitted sender) client-ip=2a01:7a0:2:106d:700::1; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a01:7a0:2:106d:700::1 as permitted sender) smtp.mailfrom=tglx@linutronix.de Received: from pd9ef12d2.dip0.t-ipconnect.de ([217.239.18.210] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1hHEMp-0006bb-27; Thu, 18 Apr 2019 23:14:47 +0200 Date: Thu, 18 Apr 2019 23:14:45 +0200 (CEST) From: Thomas Gleixner To: Josh Poimboeuf cc: LKML , x86@kernel.org, Andy Lutomirski , Steven Rostedt , Alexander Potapenko , Alexey Dobriyan , Andrew Morton , Pekka Enberg , linux-mm@kvack.org, David Rientjes , Christoph Lameter , Catalin Marinas , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Mike Rapoport , Akinobu Mita , iommu@lists.linux-foundation.org, Robin Murphy , Christoph Hellwig , Marek Szyprowski , Johannes Thumshirn , David Sterba , Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, dm-devel@redhat.com, Mike Snitzer , Alasdair Kergon , intel-gfx@lists.freedesktop.org, Joonas Lahtinen , Maarten Lankhorst , dri-devel@lists.freedesktop.org, David Airlie , Jani Nikula , Daniel Vetter , Rodrigo Vivi , linux-arch@vger.kernel.org Subject: Re: [patch V2 01/29] tracing: Cleanup stack trace code In-Reply-To: <20190418135721.5vwd6ngxagrrrrtt@treble> Message-ID: References: <20190418084119.056416939@linutronix.de> <20190418084253.142712304@linutronix.de> <20190418135721.5vwd6ngxagrrrrtt@treble> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 18 Apr 2019, Josh Poimboeuf wrote: > On Thu, Apr 18, 2019 at 10:41:20AM +0200, Thomas Gleixner wrote: > > - Remove the extra array member of stack_dump_trace[]. It's not required as > > the stack tracer stores at max array size - 1 entries so there is still > > an empty slot. > > What is the empty slot used for? I was trying to find an answer but failed. Maybe it's just historical leftovers or Steven knows where the magic is in this maze. Thanks, tglx