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>

include/asm-alpha/scatterlist.h

@@ -5,6 +5,9 @@
 #include <asm/types.h>
   
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 

include/asm-arm/scatterlist.h

@@ -5,6 +5,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;		/* buffer offset		 */
 	dma_addr_t	dma_address;	/* dma address			 */

include/asm-avr32/scatterlist.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+   unsigned long	sg_magic;
+#endif
     unsigned long	page_link;
     unsigned int	offset;
     dma_addr_t		dma_address;

include/asm-blackfin/scatterlist.h

@@ -4,6 +4,9 @@
 #include <linux/mm.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 	dma_addr_t dma_address;

include/asm-cris/scatterlist.h

@@ -2,6 +2,9 @@
 #define __ASM_CRIS_SCATTERLIST_H
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	char *  address;    /* Location data is to be transferred to */
 	unsigned int length;
 

include/asm-frv/scatterlist.h

@@ -22,6 +22,9 @@
  * and that's it. There's no excuse for not highmem enabling YOUR driver. /jens
  */
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;		/* for highmem, page offset */
 

include/asm-h8300/scatterlist.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;
 	dma_addr_t	dma_address;

include/asm-ia64/scatterlist.h

@@ -9,6 +9,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 	unsigned int length;	/* buffer length */

include/asm-m32r/scatterlist.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+    unsigned long sg_magic;
+#endif
     char *  address;    /* Location data is to be transferred to, NULL for
                          * highmem page */
     unsigned long page_link;

include/asm-m68k/scatterlist.h

@@ -4,6 +4,9 @@
 #include <linux/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 	unsigned int length;

include/asm-m68knommu/scatterlist.h

@@ -5,6 +5,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;
 	dma_addr_t	dma_address;

include/asm-mips/scatterlist.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;
 	dma_addr_t	dma_address;

include/asm-parisc/scatterlist.h

@@ -5,6 +5,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 

include/asm-powerpc/scatterlist.h

@@ -14,6 +14,9 @@
 #include <asm/dma.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 	unsigned int length;

include/asm-s390/scatterlist.h

@@ -2,6 +2,9 @@
 #define _ASMS390_SCATTERLIST_H
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+    unsigned long sg_magic;
+#endif
     unsigned long page_link;
     unsigned int offset;
     unsigned int length;

include/asm-sh/scatterlist.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+    unsigned long sg_magic;
+#endif
     unsigned long page_link;
     unsigned int offset;/* for highmem, page offset */
     dma_addr_t dma_address;

include/asm-sh64/scatterlist.h

@@ -14,6 +14,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+    unsigned long sg_magic;
+#endif
     unsigned long page_link;
     unsigned int offset;/* for highmem, page offset */
     dma_addr_t dma_address;

include/asm-sparc/scatterlist.h

@@ -5,6 +5,9 @@
 #include <linux/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 

include/asm-sparc64/scatterlist.h

@@ -6,6 +6,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;
 

include/asm-v850/scatterlist.h

@@ -17,6 +17,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned	offset;
 	dma_addr_t	dma_address;

include/asm-x86/scatterlist_32.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+    unsigned long	sg_magic;
+#endif
     unsigned long	page_link;
     unsigned int	offset;
     dma_addr_t		dma_address;

include/asm-x86/scatterlist_64.h

@@ -4,6 +4,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+    unsigned long	sg_magic;
+#endif
     unsigned long	page_link;
     unsigned int	offset;
     unsigned int	length;

include/asm-xtensa/scatterlist.h

@@ -14,6 +14,9 @@
 #include <asm/types.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long	sg_magic;
+#endif
 	unsigned long	page_link;
 	unsigned int	offset;
 	dma_addr_t	dma_address;

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
 }
 
 /**

lib/Kconfig.debug

@@ -389,6 +389,16 @@ config DEBUG_LIST
 
 	  If unsure, say N.
 
+config DEBUG_SG
+	bool "Debug SG table operations"
+	depends on DEBUG_KERNEL
+	help
+	  Enable this to turn on checks on scatter-gather tables. This can
+	  help find problems with drivers that do not properly initialize
+	  their sg tables.
+
+	  If unsure, say N.
+
 config FRAME_POINTER
 	bool "Compile the kernel with frame pointers"
 	depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN)