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[2604:1380:4601:e00::3]) by mx.google.com with ESMTPS id r13-20020a17090638cd00b00a591effe552si5433001ejd.834.2024.05.06.15.50.27 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 May 2024 15:50:27 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel+bounces-170476-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3; Authentication-Results: mx.google.com; arc=pass (i=1); spf=pass (google.com: domain of linux-kernel+bounces-170476-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-170476-linux.lists.archive=gmail.com@vger.kernel.org" Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id D134F1F225AA for ; Mon, 6 May 2024 22:50:26 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 542E215B133; Mon, 6 May 2024 22:50:19 +0000 (UTC) Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B533F13DDD6; Mon, 6 May 2024 22:50:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715035818; cv=none; b=SkkejeIULPk8pJHU7yyDOgBqws6lUuslcs6+Ic8wp5R6ndbAILR0n7lnbIXAizxgqk/vvkmYATWpP2oHAlqQpRpk16Yl5Ch3bREc4qjFb4GUro2BSYVSVssAxRKuxYI3tT/02Xr0S31FSLGPELcbfkX1YQf4s0S27loQCuFI57g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715035818; c=relaxed/simple; bh=HW1RkINGTg4M4Dd689Rj4QzJskWnTMP/SxEOVvrXQGQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=tZCWQkRQ0rZujSVtmXSk10lzE2QaWNlmJVjjesUqv22hzoS4sjc43axzSbnm0W0Zl6N3n6sYpooJA1qpvnpuk9Lk5Weq/Fv7Qa6Jf8Rg27wcb121apJ8ug19tzYXrSRWq0WO7CI96k32k7NaheFxYggYuI9aLUVa21gfMyjOQRw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7B1AC116B1; Mon, 6 May 2024 22:50:14 +0000 (UTC) Date: Mon, 6 May 2024 18:50:20 -0400 From: Steven Rostedt To: Christophe Leroy Cc: Stephen Brennan , Masami Hiramatsu , Mark Rutland , Guo Ren , Huacai Chen , WANG Xuerui , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , "Aneesh Kumar K.V" , "Naveen N. Rao" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "x86@kernel.org" , "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , "linux-trace-kernel@vger.kernel.org" , "linux-csky@vger.kernel.org" , "loongarch@lists.linux.dev" , "linux-parisc@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" Subject: Re: [PATCH v3] kprobe/ftrace: bail out if ftrace was killed Message-ID: <20240506185020.2f156bc8@gandalf.local.home> In-Reply-To: References: <20240501162956.229427-1-stephen.s.brennan@oracle.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 6 May 2024 14:46:57 +0000 Christophe Leroy wrote: > Isn't it safer to provide a fonction rather than a direct access to a > variable ? > > By the way, wouldn't it be more performant to use a static branch (jump > label) ? A static branch could work, but the point of this is that if ftrace failed, it was likely due to an issue with text modification. Do we want to stop it via text modification? -- Steve