Add CONFIG_DEBUG_SG sg validation
Add a Kconfig entry which will toggle some sanity checks on the sg
entry and tables.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index c6136e8..42daf5e 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -23,6 +23,8 @@
*
*/
+#define SG_MAGIC 0x87654321
+
/**
* sg_set_page - Set sg entry to point at given page
* @sg: SG entry
@@ -39,6 +41,9 @@
{
unsigned long page_link = sg->page_link & 0x3;
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sg->sg_magic != SG_MAGIC);
+#endif
sg->page_link = page_link | (unsigned long) page;
}
@@ -81,6 +86,9 @@
**/
static inline struct scatterlist *sg_next(struct scatterlist *sg)
{
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sg->sg_magic != SG_MAGIC);
+#endif
if (sg_is_last(sg))
return NULL;
@@ -124,6 +132,10 @@
ret = sg;
#endif
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sgl[0].sg_magic != SG_MAGIC);
+ BUG_ON(!sg_is_last(ret));
+#endif
return ret;
}
@@ -180,6 +192,9 @@
unsigned int buflen)
{
memset(sg, 0, sizeof(*sg));
+#ifdef CONFIG_DEBUG_SG
+ sg->sg_magic = SG_MAGIC;
+#endif
sg_mark_end(sg, 1);
sg_set_buf(sg, buf, buflen);
}
@@ -198,6 +213,13 @@
{
memset(sgl, 0, sizeof(*sgl) * nents);
sg_mark_end(sgl, nents);
+#ifdef CONFIG_DEBUG_SG
+ {
+ int i;
+ for (i = 0; i < nents; i++)
+ sgl[i].sg_magic = SG_MAGIC;
+ }
+#endif
}
/**