From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 58EF7624 for ; Thu, 7 Jul 2022 10:58:46 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 946BC1063; Thu, 7 Jul 2022 03:58:40 -0700 (PDT) Received: from [10.57.85.108] (unknown [10.57.85.108]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 524513F66F; Thu, 7 Jul 2022 03:58:38 -0700 (PDT) Message-ID: <569e97f6-f78c-1eae-1023-2d5e2df2d40f@arm.com> Date: Thu, 7 Jul 2022 11:58:18 +0100 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v3 04/15] iommu: Move bus setup to IOMMU device registration Content-Language: en-GB To: "Tian, Kevin" , "joro@8bytes.org" Cc: "will@kernel.org" , "iommu@lists.linux.dev" , "linux-arm-kernel@lists.infradead.org" , "baolu.lu@linux.intel.com" , "suravee.suthikulpanit@amd.com" , "vasant.hegde@amd.com" , "mjrosato@linux.ibm.com" , "gerald.schaefer@linux.ibm.com" , "schnelle@linux.ibm.com" , "linux-s390@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <5b9b608af21b3c4353af042355973bac55397962.1657034828.git.robin.murphy@arm.com> From: Robin Murphy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2022-07-07 07:51, Tian, Kevin wrote: >> From: Robin Murphy >> Sent: Wednesday, July 6, 2022 1:08 AM >> >> @@ -202,12 +210,32 @@ int iommu_device_register(struct iommu_device >> *iommu, >> spin_lock(&iommu_device_lock); >> list_add_tail(&iommu->list, &iommu_device_list); >> spin_unlock(&iommu_device_lock); >> + >> + for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) { >> + struct bus_type *bus = iommu_buses[i]; >> + int err; >> + >> + if (bus->iommu_ops && bus->iommu_ops != ops) { >> + err = -EBUSY; >> + } else { >> + bus->iommu_ops = ops; >> + err = bus_iommu_probe(bus); >> + } >> + if (err) { >> + iommu_device_unregister(iommu); >> + return err; >> + } >> + } >> + > > Probably move above into a new function bus_iommu_probe_all(): > > /* probe all buses for devices associated with this iommu */ > err = bus_iommu_probe_all(); > if (err) { > iommu_device_unregister(iommu); > return err; > } > > Just my personal preference on leaving logic in iommu_device_register() > more relevant to the iommu instance itself. On reflection I think it makes sense to pull the iommu_device_unregister() out of the loop anyway - I think that's really a left-over from between v1 and v2 when that error case briefly jumped to another cleanup loop, before I realised it was actually trivial for iommu_device_unregister() to clean up for itself. However I now see I've also missed another opportunity, and the -EBUSY case should be hoisted out of the loop as well, since checking iommu_buses[0] is sufficient. Then it's hopefully much clearer that once the bus ops go away we'll be left with just a single extra line for the loop, as in iommu_device_unregister(). Does that sound reasonable? > Apart from that: > > Reviewed-by: Kevin Tian Thanks! (and for the others as well) Robin.