From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yisheng Xie Subject: Re: [RFCv2 PATCH 09/36] iommu/fault: Allow blocking fault handlers Date: Thu, 30 Nov 2017 10:45:36 +0800 Message-ID: <3156bbca-e588-5c57-6df6-05bf9c25c747@huawei.com> References: <20171006133203.22803-1-jean-philippe.brucker@arm.com> <20171006133203.22803-10-jean-philippe.brucker@arm.com> <7e1c8ea4-e568-1000-17de-62f8562c7169@huawei.com> <74891e35-17d8-5831-1ebd-18e00ce00d74@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <74891e35-17d8-5831-1ebd-18e00ce00d74-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Jean-Philippe Brucker , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" Cc: Mark Rutland , "gabriele.paoloni-hv44wF8Li93QT0dZR+AlfA@public.gmane.org" , Catalin Marinas , Will Deacon , "okaya-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org" , "rfranz-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org" , "lenb-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org" , "dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org" , "rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org" , Sudeep Holla List-Id: linux-acpi@vger.kernel.org hi jean, On 2017/11/29 23:01, Jean-Philippe Brucker wrote: > Hello, > > On 29/11/17 06:15, Yisheng Xie wrote: >> Hi Jean, >> >> On 2017/10/6 21:31, Jean-Philippe Brucker wrote: >>> - if (domain->ext_handler) { >>> + if (domain->handler_flags & IOMMU_FAULT_HANDLER_ATOMIC) { >>> + fault->flags |= IOMMU_FAULT_ATOMIC; >> >> Why remove the condition of domain->ext_handler? should it be much better like: >> if ((domain->handler_flags & IOMMU_FAULT_HANDLER_ATOMIC) && domain->ext_handler) >> >> If domain->ext_handler is NULL, and (domain->handler_flags & IOMMU_FAULT_HANDLER_ATOMIC) >> is true. It will oops, right? > > I removed the check because ext_handler shouldn't be NULL if handler_flags > has a bit set (as per iommu_set_ext_fault_handler). But you're right that > this is fragile, and I overlooked the case where users could call > set_ext_fault_handler to clear the fault handler. > > (Note that this ext_handler will most likely be replaced by the fault > infrastructure that Jacob is working on: > https://patchwork.kernel.org/patch/10063385/ to which we should add the > atomic/blocking flags) > Get it, thanks for your explanation. Thanks Yisheng Xie > Thanks, > Jean > > . >