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Message-ID: <20150605211949.20751.59262.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Fri, 05 Jun 2015 17:19:49 -0400
From: Dan Williams <dan.j.williams@...el.com>
To: linux-kernel@...r.kernel.org
Cc: axboe@...nel.dk, boaz@...xistor.com, david@...morbit.com,
linux-arch@...r.kernel.org, arnd@...db.de,
ross.zwisler@...ux.intel.com, linux-nvdimm@...ts.01.org,
benh@...nel.crashing.org, linux-fsdevel@...r.kernel.org,
heiko.carstens@...ibm.com, hch@....de, tj@...nel.org,
paulus@...ba.org, hpa@...or.com, schwidefsky@...ibm.com,
willy@...ux.intel.com, akpm@...ux-foundation.org,
torvalds@...ux-foundation.org, mingo@...nel.org
Subject: [PATCH v4 8/9] scatterlist: convert to __pfn_t
__pfn_t replaces the struct page reference in struct scatterlist. Given
__pfn_t implements the same bits at the same bit positions for denoting
sg_is_chain() + sg_is_last() this conversion is binary identical to the
previous state.
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
include/asm-generic/pfn.h | 9 ++++
include/linux/scatterlist.h | 103 ++++++++++++++++++++++++++++++-------------
samples/kfifo/dma-example.c | 8 ++-
3 files changed, 86 insertions(+), 34 deletions(-)
diff --git a/include/asm-generic/pfn.h b/include/asm-generic/pfn.h
index e9fed20d606a..f826c50ed025 100644
--- a/include/asm-generic/pfn.h
+++ b/include/asm-generic/pfn.h
@@ -108,4 +108,13 @@ static inline __pfn_t page_to_pfn_t(struct page *page)
return pfn;
}
+
+static inline __pfn_t nth_pfn(__pfn_t pfn, unsigned int n)
+{
+ __pfn_t ret;
+
+ ret.data = (__pfn_t_to_pfn(pfn) + n) << PFN_SHIFT
+ | (pfn.data & PFN_MASK);
+ return ret;
+}
#endif /* __ASM_PFN_H */
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index eca1ec93775c..49054374646e 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -11,7 +11,7 @@ struct scatterlist {
#ifdef CONFIG_DEBUG_SG
unsigned long sg_magic;
#endif
- unsigned long page_link;
+ __pfn_t pfn;
unsigned int offset;
unsigned int length;
dma_addr_t dma_address;
@@ -44,14 +44,14 @@ struct sg_table {
/*
* Notes on SG table design.
*
- * We use the unsigned long page_link field in the scatterlist struct to place
+ * We use the __pfn_t pfn field in the scatterlist struct to place
* the page pointer AND encode information about the sg table as well. The two
* lower bits are reserved for this information.
*
- * If bit 0 is set, then the page_link contains a pointer to the next sg
+ * If PFN_SG_CHAIN is set, then the pfn contains a pointer to the next sg
* table list. Otherwise the next entry is at sg + 1.
*
- * If bit 1 is set, then this sg entry is the last element in a list.
+ * If PFN_SG_LAST is set, then this sg entry is the last element in a list.
*
* See sg_next().
*
@@ -64,10 +64,30 @@ struct sg_table {
* a valid sg entry, or whether it points to the start of a new scatterlist.
* Those low bits are there for everyone! (thanks mason :-)
*/
-#define sg_is_chain(sg) ((sg)->page_link & 0x01)
-#define sg_is_last(sg) ((sg)->page_link & 0x02)
-#define sg_chain_ptr(sg) \
- ((struct scatterlist *) ((sg)->page_link & ~0x03))
+static inline bool sg_is_chain(struct scatterlist *sg)
+{
+ return (sg->pfn.data & PFN_MASK) == PFN_SG_CHAIN;
+}
+
+static inline bool sg_is_last(struct scatterlist *sg)
+{
+ return (sg->pfn.data & PFN_MASK) == PFN_SG_LAST;
+}
+
+static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg)
+{
+ return (struct scatterlist *) (sg->pfn.data & ~PFN_MASK);
+}
+
+static inline void sg_assign_pfn(struct scatterlist *sg, __pfn_t pfn)
+{
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sg->sg_magic != SG_MAGIC);
+ BUG_ON(sg_is_chain(sg));
+#endif
+ pfn.data &= ~PFN_SG_LAST;
+ sg->pfn.data = (sg->pfn.data & PFN_SG_LAST) | pfn.data;
+}
/**
* sg_assign_page - Assign a given page to an SG entry
@@ -81,18 +101,23 @@ struct sg_table {
**/
static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
{
- unsigned long page_link = sg->page_link & 0x3;
+ __pfn_t pfn = page_to_pfn_t(page);
/*
* In order for the low bit stealing approach to work, pages
- * must be aligned at a 32-bit boundary as a minimum.
+ * must be aligned at a sizeof(unsigned long) boundary.
*/
- BUG_ON((unsigned long) page & 0x03);
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
- BUG_ON(sg_is_chain(sg));
-#endif
- sg->page_link = page_link | (unsigned long) page;
+ BUG_ON(pfn.data & PFN_MASK);
+
+ sg_assign_pfn(sg, pfn);
+}
+
+static inline void sg_set_pfn(struct scatterlist *sg, __pfn_t pfn,
+ unsigned int len, unsigned int offset)
+{
+ sg_assign_pfn(sg, pfn);
+ sg->offset = offset;
+ sg->length = len;
}
/**
@@ -112,18 +137,30 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
static inline void sg_set_page(struct scatterlist *sg, struct page *page,
unsigned int len, unsigned int offset)
{
- sg_assign_page(sg, page);
- sg->offset = offset;
- sg->length = len;
+ sg_set_pfn(sg, page_to_pfn_t(page), len, offset);
}
static inline struct page *sg_page(struct scatterlist *sg)
{
+ __pfn_t pfn = sg->pfn;
+ struct page *page;
+
#ifdef CONFIG_DEBUG_SG
BUG_ON(sg->sg_magic != SG_MAGIC);
BUG_ON(sg_is_chain(sg));
#endif
- return (struct page *)((sg)->page_link & ~0x3);
+
+ pfn.data &= ~PFN_SG_LAST;
+ page = __pfn_t_to_page(pfn);
+
+ /* don't use sg_page() on non linear-mapped memory */
+ BUG_ON(!page);
+ return page;
+}
+
+static inline unsigned long sg_pfn(struct scatterlist *sg)
+{
+ return __pfn_t_to_pfn(sg->pfn);
}
/**
@@ -175,7 +212,8 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
* Set lowest bit to indicate a link pointer, and make sure to clear
* the termination bit if it happens to be set.
*/
- prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;
+ prv[prv_nents - 1].pfn.data = ((unsigned long) sgl | PFN_SG_CHAIN)
+ & ~PFN_SG_LAST;
}
/**
@@ -195,8 +233,8 @@ static inline void sg_mark_end(struct scatterlist *sg)
/*
* Set termination bit, clear potential chain bit
*/
- sg->page_link |= 0x02;
- sg->page_link &= ~0x01;
+ sg->pfn.data |= PFN_SG_LAST;
+ sg->pfn.data &= ~PFN_SG_CHAIN;
}
/**
@@ -212,7 +250,7 @@ static inline void sg_unmark_end(struct scatterlist *sg)
#ifdef CONFIG_DEBUG_SG
BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
- sg->page_link &= ~0x02;
+ sg->pfn.data &= ~PFN_SG_LAST;
}
/**
@@ -220,14 +258,13 @@ static inline void sg_unmark_end(struct scatterlist *sg)
* @sg: SG entry
*
* Description:
- * This calls page_to_phys() on the page in this sg entry, and adds the
- * sg offset. The caller must know that it is legal to call page_to_phys()
- * on the sg page.
+ * This calls __pfn_t_to_phys() on the pfn in this sg entry, and adds the
+ * sg offset.
*
**/
static inline dma_addr_t sg_phys(struct scatterlist *sg)
{
- return page_to_phys(sg_page(sg)) + sg->offset;
+ return __pfn_t_to_phys(sg->pfn) + sg->offset;
}
/**
@@ -281,7 +318,7 @@ size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
/*
- * sg page iterator
+ * sg page / pfn iterator
*
* Iterates over sg entries page-by-page. On each successful iteration,
* you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter)
@@ -304,13 +341,19 @@ bool __sg_page_iter_next(struct sg_page_iter *piter);
void __sg_page_iter_start(struct sg_page_iter *piter,
struct scatterlist *sglist, unsigned int nents,
unsigned long pgoffset);
+
+static inline __pfn_t sg_page_iter_pfn(struct sg_page_iter *piter)
+{
+ return nth_pfn(piter->sg->pfn, piter->sg_pgoffset);
+}
+
/**
* sg_page_iter_page - get the current page held by the page iterator
* @piter: page iterator holding the page
*/
static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
{
- return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
+ return __pfn_t_to_page(sg_page_iter_pfn(piter));
}
/**
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
index aa243db93f01..3eeff9a56e0e 100644
--- a/samples/kfifo/dma-example.c
+++ b/samples/kfifo/dma-example.c
@@ -75,8 +75,8 @@ static int __init example_init(void)
for (i = 0; i < nents; i++) {
printk(KERN_INFO
"sg[%d] -> "
- "page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
- i, sg[i].page_link, sg[i].offset, sg[i].length);
+ "pfn_data 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+ i, sg[i].pfn.data, sg[i].offset, sg[i].length);
if (sg_is_last(&sg[i]))
break;
@@ -104,8 +104,8 @@ static int __init example_init(void)
for (i = 0; i < nents; i++) {
printk(KERN_INFO
"sg[%d] -> "
- "page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
- i, sg[i].page_link, sg[i].offset, sg[i].length);
+ "pfn_data 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+ i, sg[i].pfn.data, sg[i].offset, sg[i].length);
if (sg_is_last(&sg[i]))
break;
--
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