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lib/scatterlist: add sg_init_marker() helper
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>
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2 changed files with 19 additions and 8 deletions
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@ -248,6 +248,24 @@ static inline void *sg_virt(struct scatterlist *sg)
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return page_address(sg_page(sg)) + sg->offset;
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return page_address(sg_page(sg)) + sg->offset;
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}
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}
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/**
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* sg_init_marker - Initialize markers in sg table
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* @sgl: The SG table
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* @nents: Number of entries in table
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*
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**/
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static inline void sg_init_marker(struct scatterlist *sgl,
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unsigned int nents)
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{
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#ifdef CONFIG_DEBUG_SG
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unsigned int i;
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for (i = 0; i < nents; i++)
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sgl[i].sg_magic = SG_MAGIC;
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#endif
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sg_mark_end(&sgl[nents - 1]);
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}
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int sg_nents(struct scatterlist *sg);
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int sg_nents(struct scatterlist *sg);
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int sg_nents_for_len(struct scatterlist *sg, u64 len);
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int sg_nents_for_len(struct scatterlist *sg, u64 len);
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struct scatterlist *sg_next(struct scatterlist *);
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struct scatterlist *sg_next(struct scatterlist *);
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@ -132,14 +132,7 @@ EXPORT_SYMBOL(sg_last);
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void sg_init_table(struct scatterlist *sgl, unsigned int nents)
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void sg_init_table(struct scatterlist *sgl, unsigned int nents)
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{
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{
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memset(sgl, 0, sizeof(*sgl) * nents);
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memset(sgl, 0, sizeof(*sgl) * nents);
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#ifdef CONFIG_DEBUG_SG
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sg_init_marker(sgl, nents);
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{
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unsigned int i;
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for (i = 0; i < nents; i++)
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sgl[i].sg_magic = SG_MAGIC;
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}
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#endif
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sg_mark_end(&sgl[nents - 1]);
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}
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}
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EXPORT_SYMBOL(sg_init_table);
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EXPORT_SYMBOL(sg_init_table);
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