linux-kernel - [PATCH v4 01/23] lib/scatterlist: cleanup macros into static inline functions

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Date:   Wed, 17 Nov 2021 14:53:48 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-block@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian König <christian.koenig@....com>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Jakowski Andrzej <andrzej.jakowski@...el.com>,
        Minturn Dave B <dave.b.minturn@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xiong Jianxin <jianxin.xiong@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@...il.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Jason Gunthorpe <jgg@...dia.com>
Subject: [PATCH v4 01/23] lib/scatterlist: cleanup macros into static inline functions

Convert the sg_is_chain(), sg_is_last() and sg_chain_ptr() macros
into static inline functions. There's no reason for these to be macros
and static inline are generally preferred these days.

Also introduce the SG_PAGE_LINK_MASK define so the P2PDMA work, which is
adding another bit to this mask, can do so more easily.

Suggested-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 include/linux/scatterlist.h | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 266754a55327..7ff9d6386c12 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -69,10 +69,27 @@ struct sg_append_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 & SG_CHAIN)
-#define sg_is_last(sg)		((sg)->page_link & SG_END)
-#define sg_chain_ptr(sg)	\
-	((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END)))
+#define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END)
+
+static inline unsigned int __sg_flags(struct scatterlist *sg)
+{
+	return sg->page_link & SG_PAGE_LINK_MASK;
+}
+
+static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg)
+{
+	return (struct scatterlist *)(sg->page_link & ~SG_PAGE_LINK_MASK);
+}
+
+static inline bool sg_is_chain(struct scatterlist *sg)
+{
+	return __sg_flags(sg) & SG_CHAIN;
+}
+
+static inline bool sg_is_last(struct scatterlist *sg)
+{
+	return __sg_flags(sg) & SG_END;
+}
 
 /**
  * sg_assign_page - Assign a given page to an SG entry
@@ -92,7 +109,7 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
 	 * In order for the low bit stealing approach to work, pages
 	 * must be aligned at a 32-bit boundary as a minimum.
 	 */
-	BUG_ON((unsigned long) page & (SG_CHAIN | SG_END));
+	BUG_ON((unsigned long)page & SG_PAGE_LINK_MASK);
 #ifdef CONFIG_DEBUG_SG
 	BUG_ON(sg_is_chain(sg));
 #endif
@@ -126,7 +143,7 @@ static inline struct page *sg_page(struct scatterlist *sg)
 #ifdef CONFIG_DEBUG_SG
 	BUG_ON(sg_is_chain(sg));
 #endif
-	return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END));
+	return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK);
 }
 
 /**
-- 
2.30.2