kernel/kfifo.c: add handling of chained scatterlists

The current kfifo scatterlist implementation will not work with chained
scatterlists.  It assumes that struct scatterlist arrays are allocated
contiguously, which is not the case when chained scatterlists (struct
sg_table) are in use.
Signed-off-by: NStefani Seibold <stefani@seibold.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/kfifo.c

@@ -333,17 +333,16 @@ static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
 		buf += PAGE_SIZE;
 		npage = virt_to_page(buf);
 		if (page_to_phys(page) != page_to_phys(npage) - l) {
-			sgl->page_link = 0;
-			sg_set_page(sgl++, page, l - off, off);
-			if (++n == nents)
+			sg_set_page(sgl, page, l - off, off);
+			sgl = sg_next(sgl);
+			if (++n == nents || sgl == NULL)
 				return n;
 			page = npage;
 			len -= l - off;
 			l = off = 0;
 		}
 	}
-	sgl->page_link = 0;
-	sg_set_page(sgl++, page, len, off);
+	sg_set_page(sgl, page, len, off);
 	return n + 1;
 }