[RFC PATCH 27/28] PCI/P2PDMA: Remove struct pages that back P2PDMA memory

Logan Gunthorpe
2019-06-20T16:12:39Z

There are no more users of the struct pages that back P2P memory,
so convert the devm_memremap_pages() call to devm_memremap() to remove
them.

The percpu_ref and completion are retained in struct p2pdma to track
when there is no memory allocated out of the genpool and it is safe
to free it.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
drivers/pci/p2pdma.c | 107 +++++++++++++------------------------------
1 file changed, 33 insertions(+), 74 deletions(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 9b82e13f802c..83d93911f792 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -22,10 +22,6 @@
struct pci_p2pdma {
struct gen_pool *pool;
bool p2pmem_published;
-};
-
-struct p2pdma_pagemap {
- struct dev_pagemap pgmap;
struct percpu_ref ref;
struct completion ref_done;
};
@@ -78,29 +74,12 @@ static const struct attribute_group p2pmem_group = {
.name = "p2pmem",
};

-static struct p2pdma_pagemap *to_p2p_pgmap(struct percpu_ref *ref)
-{
- return container_of(ref, struct p2pdma_pagemap, ref);
-}
-
static void pci_p2pdma_percpu_release(struct percpu_ref *ref)
{
- struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
+ struct pci_p2pdma *p2pdma =
+ container_of(ref, struct pci_p2pdma, ref);

- complete(&p2p_pgmap->ref_done);
-}
-
-static void pci_p2pdma_percpu_kill(struct percpu_ref *ref)
-{
- percpu_ref_kill(ref);
-}
-
-static void pci_p2pdma_percpu_cleanup(struct percpu_ref *ref)
-{
- struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
-
- wait_for_completion(&p2p_pgmap->ref_done);
- percpu_ref_exit(&p2p_pgmap->ref);
+ complete(&p2pdma->ref_done);
}

static void pci_p2pdma_release(void *data)
@@ -111,6 +90,10 @@ static void pci_p2pdma_release(void *data)
if (!p2pdma)
return;

+ percpu_ref_kill(&p2pdma->ref);
+ wait_for_completion(&p2pdma->ref_done);
+ percpu_ref_exit(&p2pdma->ref);
+
/* Flush and disable pci_alloc_p2p_mem() */
pdev->p2pdma = NULL;
synchronize_rcu();
@@ -128,10 +111,17 @@ static int pci_p2pdma_setup(struct pci_dev *pdev)
if (!p2p)
return -ENOMEM;

+ init_completion(&p2p->ref_done);
+
p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev));
if (!p2p->pool)
goto out;

+ error = percpu_ref_init(&p2p->ref, pci_p2pdma_percpu_release, 0,
+ GFP_KERNEL);
+ if (error)
+ goto out_pool_destroy;
+
error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev);
if (error)
goto out_pool_destroy;
@@ -165,8 +155,7 @@ static int pci_p2pdma_setup(struct pci_dev *pdev)
int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
u64 offset)
{
- struct p2pdma_pagemap *p2p_pgmap;
- struct dev_pagemap *pgmap;
+ struct resource res;
void *addr;
int error;

@@ -188,50 +177,26 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
return error;
}

- p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL);
- if (!p2p_pgmap)
- return -ENOMEM;
+ res.start = pci_resource_start(pdev, bar) + offset;
+ res.end = res.start + size - 1;
+ res.flags = pci_resource_flags(pdev, bar);

- init_completion(&p2p_pgmap->ref_done);
- error = percpu_ref_init(&p2p_pgmap->ref,
- pci_p2pdma_percpu_release, 0, GFP_KERNEL);
- if (error)
- goto pgmap_free;
-
- pgmap = &p2p_pgmap->pgmap;
-
- pgmap->res.start = pci_resource_start(pdev, bar) + offset;
- pgmap->res.end = pgmap->res.start + size - 1;
- pgmap->res.flags = pci_resource_flags(pdev, bar);
- pgmap->ref = &p2p_pgmap->ref;
- pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
- pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) -
- pci_resource_start(pdev, bar);
- pgmap->kill = pci_p2pdma_percpu_kill;
- pgmap->cleanup = pci_p2pdma_percpu_cleanup;
-
- addr = devm_memremap_pages(&pdev->dev, pgmap);
- if (IS_ERR(addr)) {
- error = PTR_ERR(addr);
- goto pgmap_free;
- }
+ addr = devm_memremap(&pdev->dev, res.start, size, MEMREMAP_WC);
+ if (IS_ERR(addr))
+ return PTR_ERR(addr);

- error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr,
- pci_bus_address(pdev, bar) + offset,
- resource_size(&pgmap->res), dev_to_node(&pdev->dev),
- &p2p_pgmap->ref);
+ error = gen_pool_add_virt(pdev->p2pdma->pool, (unsigned long)addr,
+ pci_bus_address(pdev, bar) + offset, size,
+ dev_to_node(&pdev->dev));
if (error)
goto pages_free;

- pci_info(pdev, "added peer-to-peer DMA memory %pR\n",
- &pgmap->res);
+ pci_info(pdev, "added peer-to-peer DMA memory %pR\n", &res);

return 0;

pages_free:
- devm_memunmap_pages(&pdev->dev, pgmap);
-pgmap_free:
- devm_kfree(&pdev->dev, p2p_pgmap);
+ devm_memunmap(&pdev->dev, addr);
return error;
}
EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource);
@@ -601,7 +566,6 @@ EXPORT_SYMBOL_GPL(pci_p2pmem_find_many);
void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
{
void *ret = NULL;
- struct percpu_ref *ref;

/*
* Pairs with synchronize_rcu() in pci_p2pdma_release() to
@@ -612,16 +576,13 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
if (unlikely(!pdev->p2pdma))
goto out;

- ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size,
- (void **) &ref);
- if (!ret)
+ if (unlikely(!percpu_ref_tryget_live(&pdev->p2pdma->ref)))
goto out;

- if (unlikely(!percpu_ref_tryget_live(ref))) {
- gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size);
- ret = NULL;
- goto out;
- }
+ ret = (void *)gen_pool_alloc(pdev->p2pdma->pool, size);
+ if (!ret)
+ percpu_ref_put(&pdev->p2pdma->ref);
+
out:
rcu_read_unlock();
return ret;
@@ -636,11 +597,9 @@ EXPORT_SYMBOL_GPL(pci_alloc_p2pmem);
*/
void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size)
{
- struct percpu_ref *ref;
+ gen_pool_free(pdev->p2pdma->pool, (uintptr_t)addr, size);

- gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size,
- (void **) &ref);
- percpu_ref_put(ref);
+ percpu_ref_put(&pdev->p2pdma->ref);
}
EXPORT_SYMBOL_GPL(pci_free_p2pmem);

--
2.20.1