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Thu, 30 Apr 2020 07:40:17 -0700 (PDT) From: Jean-Philippe Brucker To: iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v6 02/25] iommu/ioasid: Add ioasid references Date: Thu, 30 Apr 2020 16:34:01 +0200 Message-Id: <20200430143424.2787566-3-jean-philippe@linaro.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200430143424.2787566-1-jean-philippe@linaro.org> References: <20200430143424.2787566-1-jean-philippe@linaro.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200430_074020_532874_19A31565 X-CRM114-Status: GOOD ( 14.68 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:441 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid 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, kevin.tian@intel.com, jacob.jun.pan@linux.intel.com, jgg@ziepe.ca, catalin.marinas@arm.com, joro@8bytes.org, robin.murphy@arm.com, hch@infradead.org, zhangfei.gao@linaro.org, Jean-Philippe Brucker , Jonathan.Cameron@huawei.com, felix.kuehling@amd.com, xuzaibo@huawei.com, will@kernel.org, christian.koenig@amd.com, baolu.lu@linux.intel.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Let IOASID users take references to existing ioasids with ioasid_get(). ioasid_free() drops a reference and only frees the ioasid when its reference number is zero. It returns whether the ioasid was freed. Signed-off-by: Jean-Philippe Brucker --- include/linux/ioasid.h | 10 ++++++++-- drivers/iommu/ioasid.c | 30 +++++++++++++++++++++++++++++- 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h index 6f000d7a0ddcd..609ba6f15b9e3 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_free(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_free(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/ioasid.c b/drivers/iommu/ioasid.c index 0f8dd377aada3..46511ac53e0c8 100644 --- a/drivers/iommu/ioasid.c +++ b/drivers/iommu/ioasid.c @@ -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 @@ -345,12 +347,33 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, } EXPORT_SYMBOL_GPL(ioasid_alloc); +/** + * 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); + spin_unlock(&ioasid_allocator_lock); +} +EXPORT_SYMBOL_GPL(ioasid_get); + /** * ioasid_free - Free 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_free(ioasid_t ioasid) { + bool free = false; struct ioasid_data *ioasid_data; spin_lock(&ioasid_allocator_lock); @@ -360,6 +383,10 @@ 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) { @@ -369,6 +396,7 @@ void ioasid_free(ioasid_t ioasid) exit_unlock: spin_unlock(&ioasid_allocator_lock); + return free; } EXPORT_SYMBOL_GPL(ioasid_free);