[PATCH] gfp_t: infrastructure

Beginning of gfp_t annotations:

 - -Wbitwise added to CHECKFLAGS
 - old __bitwise renamed to __bitwise__
 - __bitwise defined to either __bitwise__ or nothing, depending on
   __CHECK_ENDIAN__ being defined
 - gfp_t switched from __nocast to __bitwise__
 - force cast to gfp_t added to __GFP_... constants
 - new helper - gfp_zone(); extracts zone bits out of gfp_t value and casts
   the result to int

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 34 insertions, 28 deletions

diff --git a/Makefile b/Makefile
index 1fa7e5343464..f1d121f23025 100644
--- a/Makefile
+++ b/Makefile
@@ -334,7 +334,7 @@ KALLSYMS	= scripts/kallsyms
 PERL            = perl
 CHECK           = sparse
 
-CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ $(CF)
+CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ -Wbitwise $(CF)
 MODFLAGS        = -DMODULE
 CFLAGS_MODULE   = $(MODFLAGS)
 AFLAGS_MODULE   = $(MODFLAGS)
diff --git a/fs/buffer.c b/fs/buffer.c
index 1216c0d3c8ce..9657696fd6d7 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -502,7 +502,7 @@ static void free_more_memory(void)
         yield();
 
         for_each_pgdat(pgdat) {
-                zones = pgdat->node_zonelists[GFP_NOFS&GFP_ZONEMASK].zones;
+                zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones;
                 if (*zones)
                         try_to_free_pages(zones, GFP_NOFS);
         }
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 3010e172394d..c3779432a723 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -12,8 +12,8 @@ struct vm_area_struct;
  * GFP bitmasks..
  */
 /* Zone modifiers in GFP_ZONEMASK (see linux/mmzone.h - low two bits) */
-#define __GFP_DMA       0x01u
-#define __GFP_HIGHMEM   0x02u
+#define __GFP_DMA       ((__force gfp_t)0x01u)
+#define __GFP_HIGHMEM   ((__force gfp_t)0x02u)
 
 /*
  * Action modifiers - doesn't change the zoning
@@ -26,24 +26,24 @@ struct vm_area_struct;
  *
  * __GFP_NORETRY: The VM implementation must not retry indefinitely.
  */
-#define __GFP_WAIT      0x10u   /* Can wait and reschedule? */
-#define __GFP_HIGH      0x20u   /* Should access emergency pools? */
-#define __GFP_IO        0x40u   /* Can start physical IO? */
-#define __GFP_FS        0x80u   /* Can call down to low-level FS? */
-#define __GFP_COLD      0x100u  /* Cache-cold page required */
-#define __GFP_NOWARN    0x200u  /* Suppress page allocation failure warning */
-#define __GFP_REPEAT    0x400u  /* Retry the allocation.  Might fail */
-#define __GFP_NOFAIL    0x800u  /* Retry for ever.  Cannot fail */
-#define __GFP_NORETRY   0x1000u /* Do not retry.  Might fail */
-#define __GFP_NO_GROW   0x2000u /* Slab internal usage */
-#define __GFP_COMP      0x4000u /* Add compound page metadata */
-#define __GFP_ZERO      0x8000u /* Return zeroed page on success */
-#define __GFP_NOMEMALLOC 0x10000u /* Don't use emergency reserves */
-#define __GFP_NORECLAIM  0x20000u /* No realy zone reclaim during allocation */
-#define __GFP_HARDWALL   0x40000u /* Enforce hardwall cpuset memory allocs */
+#define __GFP_WAIT      ((__force gfp_t)0x10u)  /* Can wait and reschedule? */
+#define __GFP_HIGH      ((__force gfp_t)0x20u)  /* Should access emergency pools? */
+#define __GFP_IO        ((__force gfp_t)0x40u)  /* Can start physical IO? */
+#define __GFP_FS        ((__force gfp_t)0x80u)  /* Can call down to low-level FS? */
+#define __GFP_COLD      ((__force gfp_t)0x100u) /* Cache-cold page required */
+#define __GFP_NOWARN    ((__force gfp_t)0x200u) /* Suppress page allocation failure warning */
+#define __GFP_REPEAT    ((__force gfp_t)0x400u) /* Retry the allocation.  Might fail */
+#define __GFP_NOFAIL    ((__force gfp_t)0x800u) /* Retry for ever.  Cannot fail */
+#define __GFP_NORETRY   ((__force gfp_t)0x1000u)/* Do not retry.  Might fail */
+#define __GFP_NO_GROW   ((__force gfp_t)0x2000u)/* Slab internal usage */
+#define __GFP_COMP      ((__force gfp_t)0x4000u)/* Add compound page metadata */
+#define __GFP_ZERO      ((__force gfp_t)0x8000u)/* Return zeroed page on success */
+#define __GFP_NOMEMALLOC ((__force gfp_t)0x10000u) /* Don't use emergency reserves */
+#define __GFP_NORECLAIM  ((__force gfp_t)0x20000u) /* No realy zone reclaim during allocation */
+#define __GFP_HARDWALL   ((__force gfp_t)0x40000u) /* Enforce hardwall cpuset memory allocs */
 
 #define __GFP_BITS_SHIFT 20     /* Room for 20 __GFP_FOO bits */
-#define __GFP_BITS_MASK ((1 << __GFP_BITS_SHIFT) - 1)
+#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /* if you forget to add the bitmask here kernel will crash, period */
 #define GFP_LEVEL_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS| \
@@ -64,6 +64,7 @@ struct vm_area_struct;
 
 #define GFP_DMA         __GFP_DMA
 
+#define gfp_zone(mask) ((__force int)((mask) & (__force gfp_t)GFP_ZONEMASK))
 
 /*
  * There is only one page-allocator function, and two main namespaces to
@@ -94,7 +95,7 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
                 return NULL;
 
         return __alloc_pages(gfp_mask, order,
-                NODE_DATA(nid)->node_zonelists + (gfp_mask & GFP_ZONEMASK));
+                NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_mask));
 }
 
 #ifdef CONFIG_NUMA
diff --git a/include/linux/types.h b/include/linux/types.h
index 0aee34f9da9f..21b9ce803644 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -151,7 +151,12 @@ typedef unsigned long sector_t;
  */
 
 #ifdef __CHECKER__
-#define __bitwise __attribute__((bitwise))
+#define __bitwise__ __attribute__((bitwise))
+#else
+#define __bitwise__
+#endif
+#ifdef __CHECK_ENDIAN__
+#define __bitwise __bitwise__
 #else
 #define __bitwise
 #endif
@@ -166,7 +171,7 @@ typedef __u64 __bitwise __be64;
 #endif
 
 #ifdef __KERNEL__
-typedef unsigned __nocast gfp_t;
+typedef unsigned __bitwise__ gfp_t;
 #endif
 
 struct ustat {
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 37af443eb094..1d5c64df1653 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -700,7 +700,7 @@ static struct zonelist *zonelist_policy(gfp_t gfp, struct mempolicy *policy)
         case MPOL_BIND:
                 /* Lower zones don't get a policy applied */
                 /* Careful: current->mems_allowed might have moved */
-                if ((gfp & GFP_ZONEMASK) >= policy_zone)
+                if (gfp_zone(gfp) >= policy_zone)
                         if (cpuset_zonelist_valid_mems_allowed(policy->v.zonelist))
                                 return policy->v.zonelist;
                 /*FALL THROUGH*/
@@ -712,7 +712,7 @@ static struct zonelist *zonelist_policy(gfp_t gfp, struct mempolicy *policy)
                 nd = 0;
                 BUG();
         }
-        return NODE_DATA(nd)->node_zonelists + (gfp & GFP_ZONEMASK);
+        return NODE_DATA(nd)->node_zonelists + gfp_zone(gfp);
 }
 
 /* Do dynamic interleaving for a process */
@@ -757,7 +757,7 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order, unsigned ni
         struct page *page;
 
         BUG_ON(!node_online(nid));
-        zl = NODE_DATA(nid)->node_zonelists + (gfp & GFP_ZONEMASK);
+        zl = NODE_DATA(nid)->node_zonelists + gfp_zone(gfp);
         page = __alloc_pages(gfp, order, zl);
         if (page && page_zone(page) == zl->zones[0]) {
                 zone_pcp(zl->zones[0],get_cpu())->interleave_hit++;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e1d3d77f4aee..aa43ae3ab8c9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1089,7 +1089,7 @@ static unsigned int nr_free_zone_pages(int offset)
  */
 unsigned int nr_free_buffer_pages(void)
 {
-        return nr_free_zone_pages(GFP_USER & GFP_ZONEMASK);
+        return nr_free_zone_pages(gfp_zone(GFP_USER));
 }
 
 /*
@@ -1097,7 +1097,7 @@ unsigned int nr_free_buffer_pages(void)
  */
 unsigned int nr_free_pagecache_pages(void)
 {
-        return nr_free_zone_pages(GFP_HIGHUSER & GFP_ZONEMASK);
+        return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER));
 }
 
 #ifdef CONFIG_HIGHMEM