PCI/P2PDMA: track pgmap references per resource, not globally
In preparation for fixing a race between devm_memremap_pages_release() and the final put of a page from the device-page-map, allocate a percpu-ref per p2pdma resource mapping. Link: http://lkml.kernel.org/r/155727338646.292046.9922678317501435597.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
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795ee30648
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1570175abd
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@ -20,12 +20,16 @@
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#include <linux/seq_buf.h>
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struct pci_p2pdma {
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struct percpu_ref devmap_ref;
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struct completion devmap_ref_done;
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struct gen_pool *pool;
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bool p2pmem_published;
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};
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struct p2pdma_pagemap {
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struct dev_pagemap pgmap;
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struct percpu_ref ref;
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struct completion ref_done;
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};
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static ssize_t size_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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@ -74,41 +78,45 @@ static const struct attribute_group p2pmem_group = {
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.name = "p2pmem",
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};
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static struct p2pdma_pagemap *to_p2p_pgmap(struct percpu_ref *ref)
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{
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return container_of(ref, struct p2pdma_pagemap, ref);
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}
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static void pci_p2pdma_percpu_release(struct percpu_ref *ref)
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{
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struct pci_p2pdma *p2p =
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container_of(ref, struct pci_p2pdma, devmap_ref);
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struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
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complete_all(&p2p->devmap_ref_done);
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complete(&p2p_pgmap->ref_done);
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}
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static void pci_p2pdma_percpu_kill(struct percpu_ref *ref)
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{
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/*
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* pci_p2pdma_add_resource() may be called multiple times
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* by a driver and may register the percpu_kill devm action multiple
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* times. We only want the first action to actually kill the
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* percpu_ref.
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*/
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if (percpu_ref_is_dying(ref))
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return;
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percpu_ref_kill(ref);
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}
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static void pci_p2pdma_percpu_cleanup(void *ref)
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{
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struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
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wait_for_completion(&p2p_pgmap->ref_done);
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percpu_ref_exit(&p2p_pgmap->ref);
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}
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static void pci_p2pdma_release(void *data)
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{
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struct pci_dev *pdev = data;
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struct pci_p2pdma *p2pdma = pdev->p2pdma;
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if (!pdev->p2pdma)
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if (!p2pdma)
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return;
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wait_for_completion(&pdev->p2pdma->devmap_ref_done);
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percpu_ref_exit(&pdev->p2pdma->devmap_ref);
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gen_pool_destroy(pdev->p2pdma->pool);
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sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
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/* Flush and disable pci_alloc_p2p_mem() */
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pdev->p2pdma = NULL;
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synchronize_rcu();
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gen_pool_destroy(p2pdma->pool);
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sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
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}
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static int pci_p2pdma_setup(struct pci_dev *pdev)
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@ -124,12 +132,6 @@ static int pci_p2pdma_setup(struct pci_dev *pdev)
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if (!p2p->pool)
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goto out;
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init_completion(&p2p->devmap_ref_done);
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error = percpu_ref_init(&p2p->devmap_ref,
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pci_p2pdma_percpu_release, 0, GFP_KERNEL);
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if (error)
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goto out_pool_destroy;
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error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev);
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if (error)
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goto out_pool_destroy;
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@ -163,6 +165,7 @@ out:
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int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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u64 offset)
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{
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struct p2pdma_pagemap *p2p_pgmap;
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struct dev_pagemap *pgmap;
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void *addr;
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int error;
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@ -185,14 +188,32 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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return error;
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}
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pgmap = devm_kzalloc(&pdev->dev, sizeof(*pgmap), GFP_KERNEL);
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if (!pgmap)
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p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL);
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if (!p2p_pgmap)
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return -ENOMEM;
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init_completion(&p2p_pgmap->ref_done);
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error = percpu_ref_init(&p2p_pgmap->ref,
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pci_p2pdma_percpu_release, 0, GFP_KERNEL);
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if (error)
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goto pgmap_free;
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/*
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* FIXME: the percpu_ref_exit needs to be coordinated internal
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* to devm_memremap_pages_release(). Duplicate the same ordering
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* as other devm_memremap_pages() users for now.
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*/
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error = devm_add_action(&pdev->dev, pci_p2pdma_percpu_cleanup,
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&p2p_pgmap->ref);
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if (error)
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goto ref_cleanup;
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pgmap = &p2p_pgmap->pgmap;
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pgmap->res.start = pci_resource_start(pdev, bar) + offset;
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pgmap->res.end = pgmap->res.start + size - 1;
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pgmap->res.flags = pci_resource_flags(pdev, bar);
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pgmap->ref = &pdev->p2pdma->devmap_ref;
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pgmap->ref = &p2p_pgmap->ref;
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pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
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pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) -
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pci_resource_start(pdev, bar);
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@ -201,12 +222,13 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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addr = devm_memremap_pages(&pdev->dev, pgmap);
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if (IS_ERR(addr)) {
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error = PTR_ERR(addr);
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goto pgmap_free;
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goto ref_exit;
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}
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error = gen_pool_add_virt(pdev->p2pdma->pool, (unsigned long)addr,
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error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr,
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pci_bus_address(pdev, bar) + offset,
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resource_size(&pgmap->res), dev_to_node(&pdev->dev));
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resource_size(&pgmap->res), dev_to_node(&pdev->dev),
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&p2p_pgmap->ref);
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if (error)
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goto pages_free;
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@ -217,8 +239,10 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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pages_free:
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devm_memunmap_pages(&pdev->dev, pgmap);
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ref_cleanup:
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percpu_ref_exit(&p2p_pgmap->ref);
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pgmap_free:
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devm_kfree(&pdev->dev, pgmap);
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devm_kfree(&pdev->dev, p2p_pgmap);
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return error;
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}
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EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource);
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@ -587,19 +611,30 @@ EXPORT_SYMBOL_GPL(pci_p2pmem_find_many);
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*/
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void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
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{
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void *ret;
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void *ret = NULL;
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struct percpu_ref *ref;
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/*
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* Pairs with synchronize_rcu() in pci_p2pdma_release() to
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* ensure pdev->p2pdma is non-NULL for the duration of the
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* read-lock.
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*/
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rcu_read_lock();
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if (unlikely(!pdev->p2pdma))
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return NULL;
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goto out;
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if (unlikely(!percpu_ref_tryget_live(&pdev->p2pdma->devmap_ref)))
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return NULL;
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ret = (void *)gen_pool_alloc(pdev->p2pdma->pool, size);
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if (unlikely(!ret))
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percpu_ref_put(&pdev->p2pdma->devmap_ref);
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ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size,
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(void **) &ref);
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if (!ret)
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goto out;
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if (unlikely(!percpu_ref_tryget_live(ref))) {
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gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size);
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ret = NULL;
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goto out;
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}
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out:
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL_GPL(pci_alloc_p2pmem);
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*/
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void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size)
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{
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gen_pool_free(pdev->p2pdma->pool, (uintptr_t)addr, size);
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percpu_ref_put(&pdev->p2pdma->devmap_ref);
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struct percpu_ref *ref;
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gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size,
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(void **) &ref);
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percpu_ref_put(ref);
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}
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EXPORT_SYMBOL_GPL(pci_free_p2pmem);
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