Merge branch 'bpf-sockmap-sg-api-fixes'

Prashant Bhole says:

====================
These patches fix sg api usage in sockmap. Previously sockmap didn't
use sg_init_table(), which caused hitting BUG_ON in sg api, when
CONFIG_DEBUG_SG is enabled

v1: added sg_init_table() calls wherever needed.

v2:
- Patch1 adds new helper function in sg api. sg_init_marker()
- Patch2 sg_init_marker() and sg_init_table() in appropriate places

Backgroud:
While reviewing v1, John Fastabend raised a valid point about
unnecessary memset in sg_init_table() because sockmap uses sg table
which embedded in a struct. As enclosing struct is zeroed out, there
is unnecessary memset in sg_init_table.

So Daniel Borkmann suggested to define another static inline function
in scatterlist.h which only initializes sg_magic. Also this function
will be called from sg_init_table. From this suggestion I defined a
function sg_init_marker() which sets sg_magic and calls sg_mark_end()
====================

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

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 22b2131bcdcd..aa5d4eb725f5 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -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 *);