From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 3700C26E6FA; Wed, 4 Mar 2026 15:07:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772636833; cv=none; b=Zizcy9+HZcX+QCSHBGB17arXsIc4jpUwiLVuklir2zbhiuSCS52x0R44BVql0S+WQ8q0dWn6opLpLVf8s9/Pygv83TAJ6VCtTfYCKaBX04NDg2ZbvklICRpU2w2XPrKOw6LyMk7WQt4oeavksoonr8rYAERY57Mn1XPmtuc7Teg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772636833; c=relaxed/simple; bh=9SXhtW4k3MBZjjq2Mkcj04AbBIFzwpuFY2VgDt3g+5E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jg3O8GpBgjdKoZD94vGXT/o6rsrw7ITakRdWYxmQFLCLkb3s87/3JG+Bh1L+5fEh+ZXgitV8N81XEexJaHNvQtgQPL2LeciylfjKpuBm4wkefMxEC7wQIfIBASWpRr2UzrrLa0P1MypqRJzMaIDXbw0YSjoe8/Mu5jMLpkg9IZw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 61CD968AFE; Wed, 4 Mar 2026 16:06:59 +0100 (CET) Date: Wed, 4 Mar 2026 16:06:59 +0100 From: Christoph Hellwig To: Heiko Carstens Cc: Eric Biggers , Christoph Hellwig , Peter Zijlstra , Andrew Morton , Richard Henderson , Matt Turner , Magnus Lindholm , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "David S. Miller" , Andreas Larsson , Richard Weinberger , Anton Ivanov , Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Herbert Xu , Dan Williams , Chris Mason , David Sterba , Arnd Bergmann , Song Liu , Yu Kuai , Li Nan , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-crypto@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-arch@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: [PATCH 01/25] xor: assert that xor_blocks is not called from interrupt context Message-ID: <20260304150659.GA23393@lst.de> References: <20260226151106.144735-1-hch@lst.de> <20260226151106.144735-2-hch@lst.de> <20260227142455.GG1282955@noisy.programming.kicks-ass.net> <20260303160050.GB7021@lst.de> <20260303195517.GC2846@sol> <20260304150142.10892A0b-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-alpha@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260304150142.10892A0b-hca@linux.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) On Wed, Mar 04, 2026 at 04:01:42PM +0100, Heiko Carstens wrote: > > Because of that CPU feature check, I don't think > > "WARN_ON_ONCE(!may_use_simd())" would actually be correct here. > > > > How about "WARN_ON_ONCE(!preemptible())"? I think that covers the union > > of the context restrictions correctly. (Compared to in_task(), it > > handles the cases where hardirqs or softirqs are disabled.) > > I guess, this is not true, since there is at least one architecture which > allows to run simd code in interrupt context (but which missed to implement > may_use_simd()). I'd rather have a strict upper limit that is generally applicable. Currently there is no non-task user of this code, and while maybe doing XOR recovery for tiny blocks from irq context would be nice, let's defer that until we need it. There is much bigger fish to fry in terms of raid performance at the moment. 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA975EF8FF1 for ; Wed, 4 Mar 2026 15:07:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WmWbSuqwFx7FQyV4zlVagcKu/c9Yf3SCdIrSnsPK+bU=; b=Bp01U/Tv1Qrii8 PXgW/CkHQm8epOUh+OjCgjlhYhme1wW1jdgwyy9BH6/n73pUzzE3TyitXBCByMxHtWI9GLQ1mKhvX croMPQXzpGyYiBtI979vrOwOHu1kdevbHxwlwyJ0PPmo99RU8UK2UnHmd/B62DaPEd2roNRgGgLkI Z3rbHXxnjBUrEHmFJVD5tRTW1w6VdNuFJitBr55gjDqtLs/u9kQbgCOpuQCgnNM+HEyBO3nIJaJcO 7gb1GjG14LePL5PETi90I1yxHPF6R//ADQa7rptZoomVr75z3pJ+KZz6koa5hvnHIKZ6+XgazFC65 t6NTgCklMEo+g4/W7wYw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxnog-0000000HVq8-2zwJ; Wed, 04 Mar 2026 15:07:14 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxnoc-0000000HVpR-2D7T; Wed, 04 Mar 2026 15:07:12 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 61CD968AFE; Wed, 4 Mar 2026 16:06:59 +0100 (CET) Date: Wed, 4 Mar 2026 16:06:59 +0100 From: Christoph Hellwig To: Heiko Carstens Cc: Eric Biggers , Christoph Hellwig , Peter Zijlstra , Andrew Morton , Richard Henderson , Matt Turner , Magnus Lindholm , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "David S. Miller" , Andreas Larsson , Richard Weinberger , Anton Ivanov , Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Herbert Xu , Dan Williams , Chris Mason , David Sterba , Arnd Bergmann , Song Liu , Yu Kuai , Li Nan , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-crypto@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-arch@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: [PATCH 01/25] xor: assert that xor_blocks is not called from interrupt context Message-ID: <20260304150659.GA23393@lst.de> References: <20260226151106.144735-1-hch@lst.de> <20260226151106.144735-2-hch@lst.de> <20260227142455.GG1282955@noisy.programming.kicks-ass.net> <20260303160050.GB7021@lst.de> <20260303195517.GC2846@sol> <20260304150142.10892A0b-hca@linux.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20260304150142.10892A0b-hca@linux.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260304_070710_722522_B455C64C X-CRM114-Status: GOOD ( 19.45 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Mar 04, 2026 at 04:01:42PM +0100, Heiko Carstens wrote: > > Because of that CPU feature check, I don't think > > "WARN_ON_ONCE(!may_use_simd())" would actually be correct here. > > > > How about "WARN_ON_ONCE(!preemptible())"? I think that covers the union > > of the context restrictions correctly. (Compared to in_task(), it > > handles the cases where hardirqs or softirqs are disabled.) > > I guess, this is not true, since there is at least one architecture which > allows to run simd code in interrupt context (but which missed to implement > may_use_simd()). I'd rather have a strict upper limit that is generally applicable. Currently there is no non-task user of this code, and while maybe doing XOR recovery for tiny blocks from irq context would be nice, let's defer that until we need it. There is much bigger fish to fry in terms of raid performance at the moment. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv