lib/scatterlist: add sg_init_marker() helper (f3851786) · Commits · 戴 / test

sg_init_marker initializes sg_magic in the sg table and calls sg_mark_end() on the last entry of the table. This can be useful to avoid memset in sg_init_table() when scatterlist is already zeroed out For example: when scatterlist is embedded inside other struct and that container struct is zeroed out Suggested-by:

Daniel Borkmann <daniel@iogearbox.net> Signed-off-by:

Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp> Acked-by:

John Fastabend <john.fastabend@gmail.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

include/linux/scatterlist.h

+18 −0

Original line number	Diff line number	Diff line
		@@ -248,6 +248,24 @@ static inline void sg_virt(struct scatterlist sg)
		return page_address(sg_page(sg)) + sg->offset;
		}

		/**
		* sg_init_marker - Initialize markers in sg table
		* @sgl: The SG table
		* @nents: Number of entries in table
		*
		**/
		static inline void sg_init_marker(struct scatterlist *sgl,
		unsigned int nents)
		{
		#ifdef CONFIG_DEBUG_SG
		unsigned int i;

		for (i = 0; i < nents; i++)
		sgl[i].sg_magic = SG_MAGIC;
		#endif
		sg_mark_end(&sgl[nents - 1]);
		}

		int sg_nents(struct scatterlist *sg);
		int sg_nents_for_len(struct scatterlist *sg, u64 len);
		struct scatterlist sg_next(struct scatterlist );

lib/scatterlist.c

+1 −8

Original line number	Diff line number	Diff line
		@@ -132,14 +132,7 @@ EXPORT_SYMBOL(sg_last);
		void sg_init_table(struct scatterlist *sgl, unsigned int nents)
		{
		memset(sgl, 0, sizeof(sgl) nents);
		#ifdef CONFIG_DEBUG_SG
		{
		unsigned int i;
		for (i = 0; i < nents; i++)
		sgl[i].sg_magic = SG_MAGIC;
		}
		#endif
		sg_mark_end(&sgl[nents - 1]);
		sg_init_marker(sgl, nents);
		}
		EXPORT_SYMBOL(sg_init_table);

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