From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH v2 01/21] docs/memory-barriers.txt: Rewrite "KERNEL I/O BARRIER EFFECTS" section Date: Fri, 12 Apr 2019 12:07:09 +1000 Message-ID: References: <20190405135936.7266-1-will.deacon@arm.com> <20190405135936.7266-2-will.deacon@arm.com> <080d1ec73e3e29d6ffeeeb50b39b613da28afb37.camel@kernel.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Linus Torvalds Cc: Will Deacon , linux-arch , Linux List Kernel Mailing , "Paul E. McKenney" , Michael Ellerman , Arnd Bergmann , Peter Zijlstra , Andrea Parri , Palmer Dabbelt , Daniel Lustig , David Howells , Alan Stern , "Maciej W. Rozycki" , Paul Burton , Ingo Molnar , Yoshinori Sato , Rich Felker , Tony Luck , Mikulas Patocka , Akira List-Id: linux-arch.vger.kernel.org On Thu, 2019-04-11 at 15:34 -0700, Linus Torvalds wrote: > On Thu, Apr 11, 2019 at 3:13 PM Benjamin Herrenschmidt > wrote: > > > > Minor nit... I would have said "All readX() and writeX() accesses > > _from > > the same CPU_ to the same peripheral... and then s/the CPU/this > > CPU. > > Maybe talk about "same thread" rather than "same cpu", with the > understanding that scheduling/preemption has to include the > appropriate cross-CPU IO barrier? Works for me, but why not spell all this out in the document ? We know, but others might not. Cheers, Ben. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org ([63.228.1.57]:52087 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726640AbfDLCIU (ORCPT ); Thu, 11 Apr 2019 22:08:20 -0400 Message-ID: Subject: Re: [PATCH v2 01/21] docs/memory-barriers.txt: Rewrite "KERNEL I/O BARRIER EFFECTS" section From: Benjamin Herrenschmidt Date: Fri, 12 Apr 2019 12:07:09 +1000 In-Reply-To: References: <20190405135936.7266-1-will.deacon@arm.com> <20190405135936.7266-2-will.deacon@arm.com> <080d1ec73e3e29d6ffeeeb50b39b613da28afb37.camel@kernel.crashing.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Linus Torvalds Cc: Will Deacon , linux-arch , Linux List Kernel Mailing , "Paul E. McKenney" , Michael Ellerman , Arnd Bergmann , Peter Zijlstra , Andrea Parri , Palmer Dabbelt , Daniel Lustig , David Howells , Alan Stern , "Maciej W. Rozycki" , Paul Burton , Ingo Molnar , Yoshinori Sato , Rich Felker , Tony Luck , Mikulas Patocka , Akira Yokosawa , Luis Chamberlain , Nicholas Piggin Message-ID: <20190412020709.JjAg2RxShUtSggP1RFhmPNXs0YHMbdXLm5oQi-azaco@z> On Thu, 2019-04-11 at 15:34 -0700, Linus Torvalds wrote: > On Thu, Apr 11, 2019 at 3:13 PM Benjamin Herrenschmidt > wrote: > > > > Minor nit... I would have said "All readX() and writeX() accesses > > _from > > the same CPU_ to the same peripheral... and then s/the CPU/this > > CPU. > > Maybe talk about "same thread" rather than "same cpu", with the > understanding that scheduling/preemption has to include the > appropriate cross-CPU IO barrier? Works for me, but why not spell all this out in the document ? We know, but others might not. Cheers, Ben.