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Tue, 08 Sep 2020 05:52:29 -0400 X-MC-Unique: O5wdYovPPNCyw0Glgl4CIg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 705CA87309E; Tue, 8 Sep 2020 09:52:27 +0000 (UTC) Received: from [10.36.114.107] (ovpn-114-107.ams2.redhat.com [10.36.114.107]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D6E317E30C; Tue, 8 Sep 2020 09:52:20 +0000 (UTC) Subject: Re: [PATCH RESEND v9 02/13] iommu/ioasid: Add ioasid references To: Jean-Philippe Brucker , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org References: <20200817171558.325917-1-jean-philippe@linaro.org> <20200817171558.325917-3-jean-philippe@linaro.org> From: Auger Eric Message-ID: <2c4bf41e-aefa-de43-6100-d2b01494ba5b@redhat.com> Date: Tue, 8 Sep 2020 11:52:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200817171558.325917-3-jean-philippe@linaro.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eric.auger@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200908_055235_193648_2691B064 X-CRM114-Status: GOOD ( 28.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fenghua.yu@intel.com, will@kernel.org, zhengxiang9@huawei.com, catalin.marinas@arm.com, zhangfei.gao@linaro.org, robin.murphy@arm.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Jean, On 8/17/20 7:15 PM, Jean-Philippe Brucker wrote: > Let IOASID users take references to existing ioasids with ioasid_get(). > ioasid_put() drops a reference and only frees the ioasid when its > reference number is zero. It returns true if the ioasid was freed. > For drivers that don't call ioasid_get(), ioasid_put() is the same as > ioasid_free(). > > Reviewed-by: Lu Baolu > Signed-off-by: Jean-Philippe Brucker Reviewed-by: Eric Auger Thanks Eric > --- > include/linux/ioasid.h | 10 ++++++++-- > drivers/iommu/intel/iommu.c | 4 ++-- > drivers/iommu/intel/svm.c | 6 +++--- > drivers/iommu/ioasid.c | 38 +++++++++++++++++++++++++++++++++---- > 4 files changed, 47 insertions(+), 11 deletions(-) > > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h > index 6f000d7a0ddc..e9dacd4b9f6b 100644 > --- a/include/linux/ioasid.h > +++ b/include/linux/ioasid.h > @@ -34,7 +34,8 @@ struct ioasid_allocator_ops { > #if IS_ENABLED(CONFIG_IOASID) > ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, > void *private); > -void ioasid_free(ioasid_t ioasid); > +void ioasid_get(ioasid_t ioasid); > +bool ioasid_put(ioasid_t ioasid); > void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, > bool (*getter)(void *)); > int ioasid_register_allocator(struct ioasid_allocator_ops *allocator); > @@ -48,10 +49,15 @@ static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, > return INVALID_IOASID; > } > > -static inline void ioasid_free(ioasid_t ioasid) > +static inline void ioasid_get(ioasid_t ioasid) > { > } > > +static inline bool ioasid_put(ioasid_t ioasid) > +{ > + return false; > +} > + > static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, > bool (*getter)(void *)) > { > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > index e9864e52b0e9..152fc2dc17e0 100644 > --- a/drivers/iommu/intel/iommu.c > +++ b/drivers/iommu/intel/iommu.c > @@ -5149,7 +5149,7 @@ static void auxiliary_unlink_device(struct dmar_domain *domain, > domain->auxd_refcnt--; > > if (!domain->auxd_refcnt && domain->default_pasid > 0) > - ioasid_free(domain->default_pasid); > + ioasid_put(domain->default_pasid); > } > > static int aux_domain_add_dev(struct dmar_domain *domain, > @@ -5210,7 +5210,7 @@ static int aux_domain_add_dev(struct dmar_domain *domain, > spin_unlock(&iommu->lock); > spin_unlock_irqrestore(&device_domain_lock, flags); > if (!domain->auxd_refcnt && domain->default_pasid > 0) > - ioasid_free(domain->default_pasid); > + ioasid_put(domain->default_pasid); > > return ret; > } > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c > index 95c3164a2302..50897a2bd1da 100644 > --- a/drivers/iommu/intel/svm.c > +++ b/drivers/iommu/intel/svm.c > @@ -565,7 +565,7 @@ intel_svm_bind_mm(struct device *dev, int flags, struct svm_dev_ops *ops, > if (mm) { > ret = mmu_notifier_register(&svm->notifier, mm); > if (ret) { > - ioasid_free(svm->pasid); > + ioasid_put(svm->pasid); > kfree(svm); > kfree(sdev); > goto out; > @@ -583,7 +583,7 @@ intel_svm_bind_mm(struct device *dev, int flags, struct svm_dev_ops *ops, > if (ret) { > if (mm) > mmu_notifier_unregister(&svm->notifier, mm); > - ioasid_free(svm->pasid); > + ioasid_put(svm->pasid); > kfree(svm); > kfree(sdev); > goto out; > @@ -652,7 +652,7 @@ static int intel_svm_unbind_mm(struct device *dev, int pasid) > kfree_rcu(sdev, rcu); > > if (list_empty(&svm->devs)) { > - ioasid_free(svm->pasid); > + ioasid_put(svm->pasid); > if (svm->mm) > mmu_notifier_unregister(&svm->notifier, svm->mm); > list_del(&svm->list); > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c > index 0f8dd377aada..50ee27bbd04e 100644 > --- a/drivers/iommu/ioasid.c > +++ b/drivers/iommu/ioasid.c > @@ -2,7 +2,7 @@ > /* > * I/O Address Space ID allocator. There is one global IOASID space, split into > * subsets. Users create a subset with DECLARE_IOASID_SET, then allocate and > - * free IOASIDs with ioasid_alloc and ioasid_free. > + * free IOASIDs with ioasid_alloc and ioasid_put. > */ > #include > #include > @@ -15,6 +15,7 @@ struct ioasid_data { > struct ioasid_set *set; > void *private; > struct rcu_head rcu; > + refcount_t refs; > }; > > /* > @@ -314,6 +315,7 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, > > data->set = set; > data->private = private; > + refcount_set(&data->refs, 1); > > /* > * Custom allocator needs allocator data to perform platform specific > @@ -346,11 +348,34 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, > EXPORT_SYMBOL_GPL(ioasid_alloc); > > /** > - * ioasid_free - Free an IOASID > + * ioasid_get - obtain a reference to the IOASID > + */ > +void ioasid_get(ioasid_t ioasid) > +{ > + struct ioasid_data *ioasid_data; > + > + spin_lock(&ioasid_allocator_lock); > + ioasid_data = xa_load(&active_allocator->xa, ioasid); > + if (ioasid_data) > + refcount_inc(&ioasid_data->refs); > + else > + WARN_ON(1); > + spin_unlock(&ioasid_allocator_lock); > +} > +EXPORT_SYMBOL_GPL(ioasid_get); > + > +/** > + * ioasid_put - Release a reference to an ioasid > * @ioasid: the ID to remove > + * > + * Put a reference to the IOASID, free it when the number of references drops to > + * zero. > + * > + * Return: %true if the IOASID was freed, %false otherwise. > */ > -void ioasid_free(ioasid_t ioasid) > +bool ioasid_put(ioasid_t ioasid) > { > + bool free = false; > struct ioasid_data *ioasid_data; > > spin_lock(&ioasid_allocator_lock); > @@ -360,6 +385,10 @@ void ioasid_free(ioasid_t ioasid) > goto exit_unlock; > } > > + free = refcount_dec_and_test(&ioasid_data->refs); > + if (!free) > + goto exit_unlock; > + > active_allocator->ops->free(ioasid, active_allocator->ops->pdata); > /* Custom allocator needs additional steps to free the xa element */ > if (active_allocator->flags & IOASID_ALLOCATOR_CUSTOM) { > @@ -369,8 +398,9 @@ void ioasid_free(ioasid_t ioasid) > > exit_unlock: > spin_unlock(&ioasid_allocator_lock); > + return free; > } > -EXPORT_SYMBOL_GPL(ioasid_free); > +EXPORT_SYMBOL_GPL(ioasid_put); > > /** > * ioasid_find - Find IOASID data > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel