Change table chaining layout
Change the page member of the scatterlist structure to be an unsigned long, and encode more stuff in the lower bits: - Bits 0 and 1 zero: this is a normal sg entry. Next sg entry is located at sg + 1. - Bit 0 set: this is a chain entry, the next real entry is at ->page_link with the two low bits masked off. - Bit 1 set: this is the final entry in the sg entry. sg_next() will return NULL when passed such an entry. It's thus important that sg table users use the proper accessors to get and set the page member. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe
Родитель
58b053e4ce
Коммит
18dabf473e
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@ -5,7 +5,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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@ -5,7 +5,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page; /* buffer page */
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unsigned long page_link;
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unsigned int offset; /* buffer offset */
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dma_addr_t dma_address; /* dma address */
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unsigned int length; /* length */
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@ -4,7 +4,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -4,7 +4,7 @@
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#include <linux/mm.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -6,7 +6,7 @@ struct scatterlist {
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unsigned int length;
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/* The following is i386 highmem junk - not used by us */
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struct page * page; /* Location for highmem page, if any */
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unsigned long page_link;
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unsigned int offset;/* for highmem, page offset */
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};
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@ -22,7 +22,7 @@
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* and that's it. There's no excuse for not highmem enabling YOUR driver. /jens
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*/
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struct scatterlist {
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struct page *page; /* Location for highmem page, if any */
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unsigned long page_link;
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unsigned int offset; /* for highmem, page offset */
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dma_addr_t dma_address;
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@ -4,7 +4,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -9,7 +9,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length; /* buffer length */
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@ -6,7 +6,7 @@
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struct scatterlist {
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char * address; /* Location data is to be transferred to, NULL for
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* highmem page */
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struct page * page; /* Location for highmem page, if any */
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unsigned long page_link;
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unsigned int offset;/* for highmem, page offset */
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dma_addr_t dma_address;
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@ -4,7 +4,7 @@
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#include <linux/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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@ -5,7 +5,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -4,7 +4,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page * page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -5,7 +5,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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@ -14,7 +14,7 @@
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#include <asm/dma.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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@ -2,7 +2,7 @@
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#define _ASMS390_SCATTERLIST_H
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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};
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@ -4,7 +4,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page * page; /* Location for highmem page, if any */
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unsigned long page_link;
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unsigned int offset;/* for highmem, page offset */
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dma_addr_t dma_address;
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unsigned int length;
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@ -14,7 +14,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page * page; /* Location for highmem page, if any */
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unsigned long page_link;
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unsigned int offset;/* for highmem, page offset */
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dma_addr_t dma_address;
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unsigned int length;
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@ -5,7 +5,7 @@
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#include <linux/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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@ -6,7 +6,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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@ -17,7 +17,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned offset;
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dma_addr_t dma_address;
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unsigned length;
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@ -45,9 +45,9 @@ dma_map_sg(struct device *dev, struct scatterlist *sglist, int nents,
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WARN_ON(nents == 0 || sglist[0].length == 0);
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for_each_sg(sglist, sg, nents, i) {
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BUG_ON(!sg->page);
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BUG_ON(!sg_page(sg));
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sg->dma_address = page_to_phys(sg->page) + sg->offset;
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sg->dma_address = sg_phys(sg);
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}
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flush_write_buffers();
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@ -4,7 +4,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -4,7 +4,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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unsigned int length;
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dma_addr_t dma_address;
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@ -14,7 +14,7 @@
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#include <asm/types.h>
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struct scatterlist {
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struct page *page;
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unsigned long page_link;
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unsigned int offset;
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dma_addr_t dma_address;
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unsigned int length;
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@ -2,9 +2,26 @@
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#define _LINUX_SCATTERLIST_H
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#include <asm/scatterlist.h>
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#include <asm/io.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <asm/io.h>
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/*
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* Notes on SG table design.
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*
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* Architectures must provide an unsigned long page_link field in the
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* scatterlist struct. We use that to place the page pointer AND encode
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* information about the sg table as well. The two lower bits are reserved
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* for this information.
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*
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* If bit 0 is set, then the page_link contains a pointer to the next sg
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* table list. Otherwise the next entry is at sg + 1.
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*
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* If bit 1 is set, then this sg entry is the last element in a list.
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*
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* See sg_next().
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*
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*/
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/**
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* sg_set_page - Set sg entry to point at given page
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@ -20,11 +37,20 @@
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**/
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static inline void sg_set_page(struct scatterlist *sg, struct page *page)
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{
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sg->page = page;
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unsigned long page_link = sg->page_link & 0x3;
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sg->page_link = page_link | (unsigned long) page;
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}
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#define sg_page(sg) ((sg)->page)
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#define sg_page(sg) ((struct page *) ((sg)->page_link & ~0x3))
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/**
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* sg_set_buf - Set sg entry to point at given data
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* @sg: SG entry
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* @buf: Data
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* @buflen: Data length
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*
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**/
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static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
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unsigned int buflen)
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{
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@ -38,26 +64,27 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
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* a valid sg entry, or whether it points to the start of a new scatterlist.
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* Those low bits are there for everyone! (thanks mason :-)
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*/
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#define sg_is_chain(sg) ((unsigned long) (sg)->page & 0x01)
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#define sg_is_chain(sg) ((sg)->page_link & 0x01)
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#define sg_is_last(sg) ((sg)->page_link & 0x02)
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#define sg_chain_ptr(sg) \
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((struct scatterlist *) ((unsigned long) (sg)->page & ~0x01))
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((struct scatterlist *) ((sg)->page_link & ~0x03))
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/**
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* sg_next - return the next scatterlist entry in a list
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* @sg: The current sg entry
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*
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* Usually the next entry will be @sg@ + 1, but if this sg element is part
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* of a chained scatterlist, it could jump to the start of a new
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* scatterlist array.
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* Description:
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* Usually the next entry will be @sg@ + 1, but if this sg element is part
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* of a chained scatterlist, it could jump to the start of a new
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* scatterlist array.
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*
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* Note that the caller must ensure that there are further entries after
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* the current entry, this function will NOT return NULL for an end-of-list.
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*
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*/
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**/
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static inline struct scatterlist *sg_next(struct scatterlist *sg)
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{
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sg++;
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if (sg_is_last(sg))
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return NULL;
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sg++;
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if (unlikely(sg_is_chain(sg)))
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sg = sg_chain_ptr(sg);
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@ -75,14 +102,15 @@ static inline struct scatterlist *sg_next(struct scatterlist *sg)
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* @sgl: First entry in the scatterlist
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* @nents: Number of entries in the scatterlist
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*
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* Should only be used casually, it (currently) scan the entire list
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* to get the last entry.
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* Description:
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* Should only be used casually, it (currently) scan the entire list
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* to get the last entry.
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*
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* Note that the @sgl@ pointer passed in need not be the first one,
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* the important bit is that @nents@ denotes the number of entries that
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* exist from @sgl@.
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* Note that the @sgl@ pointer passed in need not be the first one,
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* the important bit is that @nents@ denotes the number of entries that
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* exist from @sgl@.
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*
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*/
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**/
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static inline struct scatterlist *sg_last(struct scatterlist *sgl,
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unsigned int nents)
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{
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@ -105,16 +133,17 @@ static inline struct scatterlist *sg_last(struct scatterlist *sgl,
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* @prv_nents: Number of entries in prv
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* @sgl: Second scatterlist
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*
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* Links @prv@ and @sgl@ together, to form a longer scatterlist.
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* Description:
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* Links @prv@ and @sgl@ together, to form a longer scatterlist.
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*
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*/
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**/
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static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
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struct scatterlist *sgl)
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{
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#ifndef ARCH_HAS_SG_CHAIN
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BUG();
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#endif
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prv[prv_nents - 1].page = (struct page *) ((unsigned long) sgl | 0x01);
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prv[prv_nents - 1].page_link = (unsigned long) sgl | 0x01;
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}
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/**
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@ -128,13 +157,14 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
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**/
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static inline void sg_mark_end(struct scatterlist *sgl, unsigned int nents)
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{
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sgl[nents - 1].page_link = 0x02;
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}
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static inline void __sg_mark_end(struct scatterlist *sg)
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{
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sg->page_link |= 0x02;
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}
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/**
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* sg_init_one - Initialize a single entry sg list
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* @sg: SG entry
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@ -187,7 +217,7 @@ static inline unsigned long sg_phys(struct scatterlist *sg)
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/**
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* sg_virt - Return virtual address of an sg entry
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* @sg: SG entry
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* @sg: SG entry
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*
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* Description:
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* This calls page_address() on the page in this sg entry, and adds the
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