sg: remove ->sg_magic member
This was introduced more than a decade ago when sg chaining was
added, but we never really caught anything with it. The scatterlist
entry size can be critical, since drivers allocate it, so remove
the magic member. Recently it's been triggering allocation stalls
and failures in NVMe.
Tested-by: Jordan Glover <Golden_Miller83@protonmail.ch>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 34c125e..9180f67 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2238,9 +2238,6 @@ static inline struct scatterlist *____sg_next(struct scatterlist *sg)
**/
static inline struct scatterlist *__sg_next(struct scatterlist *sg)
{
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
-#endif
return sg_is_last(sg) ? NULL : ____sg_next(sg);
}
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 51f5202..093aa57 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -9,9 +9,6 @@
#include <asm/io.h>
struct scatterlist {
-#ifdef CONFIG_DEBUG_SG
- unsigned long sg_magic;
-#endif
unsigned long page_link;
unsigned int offset;
unsigned int length;
@@ -64,7 +61,6 @@ struct sg_table {
*
*/
-#define SG_MAGIC 0x87654321
#define SG_CHAIN 0x01UL
#define SG_END 0x02UL
@@ -98,7 +94,6 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
*/
BUG_ON((unsigned long) page & (SG_CHAIN | SG_END));
#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
BUG_ON(sg_is_chain(sg));
#endif
sg->page_link = page_link | (unsigned long) page;
@@ -129,7 +124,6 @@ static inline void sg_set_page(struct scatterlist *sg, struct page *page,
static inline struct page *sg_page(struct scatterlist *sg)
{
#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
BUG_ON(sg_is_chain(sg));
#endif
return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END));
@@ -195,9 +189,6 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
**/
static inline void sg_mark_end(struct scatterlist *sg)
{
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
-#endif
/*
* Set termination bit, clear potential chain bit
*/
@@ -215,9 +206,6 @@ static inline void sg_mark_end(struct scatterlist *sg)
**/
static inline void sg_unmark_end(struct scatterlist *sg)
{
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
-#endif
sg->page_link &= ~SG_END;
}
@@ -260,12 +248,6 @@ static inline void *sg_virt(struct scatterlist *sg)
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]);
}
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 06dad7a..d4ae67d 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -24,9 +24,6 @@
**/
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;
@@ -111,10 +108,7 @@ struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
for_each_sg(sgl, sg, nents, i)
ret = sg;
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sgl[0].sg_magic != SG_MAGIC);
BUG_ON(!sg_is_last(ret));
-#endif
return ret;
}
EXPORT_SYMBOL(sg_last);
diff --git a/tools/virtio/linux/scatterlist.h b/tools/virtio/linux/scatterlist.h
index 9a45f90..369ee30 100644
--- a/tools/virtio/linux/scatterlist.h
+++ b/tools/virtio/linux/scatterlist.h
@@ -36,7 +36,6 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
*/
BUG_ON((unsigned long) page & 0x03);
#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
BUG_ON(sg_is_chain(sg));
#endif
sg->page_link = page_link | (unsigned long) page;
@@ -67,7 +66,6 @@ static inline void sg_set_page(struct scatterlist *sg, struct page *page,
static inline struct page *sg_page(struct scatterlist *sg)
{
#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
BUG_ON(sg_is_chain(sg));
#endif
return (struct page *)((sg)->page_link & ~0x3);
@@ -116,9 +114,6 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
**/
static inline void sg_mark_end(struct scatterlist *sg)
{
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
-#endif
/*
* Set termination bit, clear potential chain bit
*/
@@ -136,17 +131,11 @@ static inline void sg_mark_end(struct scatterlist *sg)
**/
static inline void sg_unmark_end(struct scatterlist *sg)
{
-#ifdef CONFIG_DEBUG_SG
- BUG_ON(sg->sg_magic != SG_MAGIC);
-#endif
sg->page_link &= ~0x02;
}
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;
@@ -160,13 +149,6 @@ static inline struct scatterlist *sg_next(struct scatterlist *sg)
static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
{
memset(sgl, 0, sizeof(*sgl) * 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]);
}