From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752624AbcCJLxG (ORCPT ); Thu, 10 Mar 2016 06:53:06 -0500 Received: from foss.arm.com ([217.140.101.70]:45184 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751789AbcCJLxA (ORCPT ); Thu, 10 Mar 2016 06:53:00 -0500 Date: Thu, 10 Mar 2016 11:52:54 +0000 From: Jean-Philippe Brucker To: Eric Auger Cc: eric.auger@st.com, robin.murphy@arm.com, alex.williamson@redhat.com, will.deacon@arm.com, joro@8bytes.org, tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com, christoffer.dall@linaro.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, patches@linaro.org, Manish.Jaggi@caviumnetworks.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org Subject: Re: [RFC v5 06/17] dma-reserved-iommu: iommu_get/put_single_reserved Message-ID: <20160310115253.GA14609@e106794-lin.cambridge.arm.com> References: <1456856877-4817-1-git-send-email-eric.auger@linaro.org> <1456856877-4817-7-git-send-email-eric.auger@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1456856877-4817-7-git-send-email-eric.auger@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Eric, On Tue, Mar 01, 2016 at 06:27:46PM +0000, Eric Auger wrote: >[...] > + > +int iommu_get_single_reserved(struct iommu_domain *domain, > + phys_addr_t addr, int prot, > + dma_addr_t *iova) > +{ > + unsigned long order = __ffs(domain->ops->pgsize_bitmap); > + size_t page_size = 1 << order; > + phys_addr_t mask = page_size - 1; > + phys_addr_t aligned_addr = addr & ~mask; > + phys_addr_t offset = addr - aligned_addr; > + struct iommu_reserved_binding *b; > + struct iova *p_iova; > + struct iova_domain *iovad = > + (struct iova_domain *)domain->reserved_iova_cookie; > + int ret; > + > + if (!iovad) > + return -EINVAL; > + > + mutex_lock(&domain->reserved_mutex); I believe this function could get called from the chunk of __setup_irq that is executed atomically: * request_threaded_irq * __setup_irq * irq_startup * irq_domain_activate_irq * msi_domain_activate * msi_compose * iommu_get_single_reserved If this is the case, we should probably use a spinlock to protect the iova_domain... > + > + b = find_reserved_binding(domain, aligned_addr, page_size); > + if (b) { > + *iova = b->iova + offset; > + kref_get(&b->kref); > + ret = 0; > + goto unlock; > + } > + > + /* there is no existing reserved iova for this pa */ > + p_iova = alloc_iova(iovad, 1, iovad->dma_32bit_pfn, true); > + if (!p_iova) { > + ret = -ENOMEM; > + goto unlock; > + } > + *iova = p_iova->pfn_lo << order; > + > + b = kzalloc(sizeof(*b), GFP_KERNEL); ... and GFP_ATOMIC here. Thanks, Jean-Philippe > + if (!b) { > + ret = -ENOMEM; > + goto free_iova_unlock; > + } > + > + ret = iommu_map(domain, *iova, aligned_addr, page_size, prot); > + if (ret) > + goto free_binding_iova_unlock; > + > + kref_init(&b->kref); > + kref_get(&b->kref); > + b->domain = domain; > + b->addr = aligned_addr; > + b->iova = *iova; > + b->size = page_size; > + > + link_reserved_binding(domain, b); > + > + *iova += offset; > + goto unlock; > + > +free_binding_iova_unlock: > + kfree(b); > +free_iova_unlock: > + free_iova(iovad, *iova >> order); > +unlock: > + mutex_unlock(&domain->reserved_mutex); > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_get_single_reserved);