[RFC PATCH 26/28] PCI/P2PDMA: Remove SGL helpers

Logan Gunthorpe
2019-06-20T16:12:38Z

The functions, pci_p2pmem_alloc_sgl(), pci_p2pmem_free_sgl() and
pci_p2pdma_map_sg() no longer have any callers, so remove them.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
Documentation/driver-api/pci/p2pdma.rst | 9 +--
drivers/pci/p2pdma.c | 95 -------------------------
include/linux/pci-p2pdma.h | 19 -----
3 files changed, 3 insertions(+), 120 deletions(-)

diff --git a/Documentation/driver-api/pci/p2pdma.rst b/Documentation/driver-api/pci/p2pdma.rst
index 44deb52beeb4..5b19c420d921 100644
--- a/Documentation/driver-api/pci/p2pdma.rst
+++ b/Documentation/driver-api/pci/p2pdma.rst
@@ -84,9 +84,8 @@ Client Drivers
--------------

A client driver typically only has to conditionally change its DMA map
-routine to use the mapping function :c:func:`pci_p2pdma_map_sg()` instead
-of the usual :c:func:`dma_map_sg()` function. Memory mapped in this
-way does not need to be unmapped.
+routine to use the PCI bus address with :c:func:`pci_p2pmem_virt_to_bus()`
+for the DMA address instead of the usual :c:func:`dma_map_sg()` function.

The client may also, optionally, make use of
:c:func:`is_pci_p2pdma_page()` to determine when to use the P2P mapping
@@ -117,9 +116,7 @@ returned with pci_dev_put().

Once a provider is selected, the orchestrator can then use
:c:func:`pci_alloc_p2pmem()` and :c:func:`pci_free_p2pmem()` to
-allocate P2P memory from the provider. :c:func:`pci_p2pmem_alloc_sgl()`
-and :c:func:`pci_p2pmem_free_sgl()` are convenience functions for
-allocating scatter-gather lists with P2P memory.
+allocate P2P memory from the provider.

Struct Page Caveats
-------------------
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index a98126ad9c3a..9b82e13f802c 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -666,60 +666,6 @@ pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr)
}
EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus);

-/**
- * pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist
- * @pdev: the device to allocate memory from
- * @nents: the number of SG entries in the list
- * @length: number of bytes to allocate
- *
- * Return: %NULL on error or &struct scatterlist pointer and @nents on success
- */
-struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
- unsigned int *nents, u32 length)
-{
- struct scatterlist *sg;
- void *addr;
-
- sg = kzalloc(sizeof(*sg), GFP_KERNEL);
- if (!sg)
- return NULL;
-
- sg_init_table(sg, 1);
-
- addr = pci_alloc_p2pmem(pdev, length);
- if (!addr)
- goto out_free_sg;
-
- sg_set_buf(sg, addr, length);
- *nents = 1;
- return sg;
-
-out_free_sg:
- kfree(sg);
- return NULL;
-}
-EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl);
-
-/**
- * pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl()
- * @pdev: the device to allocate memory from
- * @sgl: the allocated scatterlist
- */
-void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl)
-{
- struct scatterlist *sg;
- int count;
-
- for_each_sg(sgl, sg, INT_MAX, count) {
- if (!sg)
- break;
-
- pci_free_p2pmem(pdev, sg_virt(sg), sg->length);
- }
- kfree(sgl);
-}
-EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl);
-
/**
* pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by
* other devices with pci_p2pmem_find()
@@ -738,47 +684,6 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
}
EXPORT_SYMBOL_GPL(pci_p2pmem_publish);

-/**
- * pci_p2pdma_map_sg - map a PCI peer-to-peer scatterlist for DMA
- * @dev: device doing the DMA request
- * @sg: scatter list to map
- * @nents: elements in the scatterlist
- * @dir: DMA direction
- *
- * Scatterlists mapped with this function should not be unmapped in any way.
- *
- * Returns the number of SG entries mapped or 0 on error.
- */
-int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
- enum dma_data_direction dir)
-{
- struct dev_pagemap *pgmap;
- struct scatterlist *s;
- phys_addr_t paddr;
- int i;
-
- /*
- * p2pdma mappings are not compatible with devices that use
- * dma_virt_ops. If the upper layers do the right thing
- * this should never happen because it will be prevented
- * by the check in pci_p2pdma_add_client()
- */
- if (WARN_ON_ONCE(IS_ENABLED(CONFIG_DMA_VIRT_OPS) &&
- dev->dma_ops == &dma_virt_ops))
- return 0;
-
- for_each_sg(sg, s, nents, i) {
- pgmap = sg_page(s)->pgmap;
- paddr = sg_phys(s);
-
- s->dma_address = paddr - pgmap->pci_p2pdma_bus_offset;
- sg_dma_len(s) = s->length;
- }
-
- return nents;
-}
-EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg);
-
/**
* pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
* to enable p2pdma
diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index bca9bc3e5be7..4a75a3f43444 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h
@@ -26,12 +26,7 @@ struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients);
void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size);
void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size);
pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr);
-struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
- unsigned int *nents, u32 length);
-void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl);
void pci_p2pmem_publish(struct pci_dev *pdev, bool publish);
-int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
- enum dma_data_direction dir);
int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
bool *use_p2pdma);
ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
@@ -69,23 +64,9 @@ static inline pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev,
{
return 0;
}
-static inline struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
- unsigned int *nents, u32 length)
-{
- return NULL;
-}
-static inline void pci_p2pmem_free_sgl(struct pci_dev *pdev,
- struct scatterlist *sgl)
-{
-}
static inline void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
{
}
-static inline int pci_p2pdma_map_sg(struct device *dev,
- struct scatterlist *sg, int nents, enum dma_data_direction dir)
-{
- return 0;
-}
static inline int pci_p2pdma_enable_store(const char *page,
struct pci_dev **p2p_dev, bool *use_p2pdma)
{
--
2.20.1