Add CONFIG_DEBUG_SG sg validation

[mirror_ubuntu-artful-kernel.git] / include / linux / scatterlist.h

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index c6136e8a7f58fcb561ffc042b501e7a9f554c1a1..42daf5e1526592e351fdcafe464565a5d272682a 100644 (file)
--- 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 @@ static inline void sg_set_page(struct scatterlist *sg, struct page *page)
 {
        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 void sg_set_buf(struct scatterlist *sg, const void *buf,
  **/
 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;
 
@@ -123,6 +131,10 @@ static inline struct scatterlist *sg_last(struct scatterlist *sgl,
        for_each_sg(sgl, sg, nents, i)
                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 @@ static inline void sg_init_one(struct scatterlist *sg, const void *buf,
                               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 @@ static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
 {
        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
 }
 
 /**