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authorHarvey Harrison <harvey.harrison@gmail.com>2008-04-28 02:12:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:17 -0700
commitddc81ed2c5d47a078a3b02c5c3a4345bc2bc3c9b (patch)
tree2bd3e56604350d05d5163e32dde7fbbe56d31586
parent488514d1798289f56f80ed018e246179fe500383 (diff)
remove sparse warning for mmzone.h
include/linux/mmzone.h:640:22: warning: potentially expensive pointer subtraction Calculate the offset into the node_zones array rather than the index using casts to (char *) and comparing against the index * sizeof(struct zone). On X86_32 this saves a sar, but code size increases by one byte per is_highmem() use due to 32-bit cmps rather than 16 bit cmps. Before: 207: 2b 80 8c 07 00 00 sub 0x78c(%eax),%eax 20d: c1 f8 0b sar $0xb,%eax 210: 83 f8 02 cmp $0x2,%eax 213: 74 16 je 22b <kmap_atomic_prot+0x144> 215: 83 f8 03 cmp $0x3,%eax 218: 0f 85 8f 00 00 00 jne 2ad <kmap_atomic_prot+0x1c6> 21e: 83 3d 00 00 00 00 02 cmpl $0x2,0x0 225: 0f 85 82 00 00 00 jne 2ad <kmap_atomic_prot+0x1c6> 22b: 64 a1 00 00 00 00 mov %fs:0x0,%eax After: 207: 2b 80 8c 07 00 00 sub 0x78c(%eax),%eax 20d: 3d 00 10 00 00 cmp $0x1000,%eax 212: 74 18 je 22c <kmap_atomic_prot+0x145> 214: 3d 00 18 00 00 cmp $0x1800,%eax 219: 0f 85 8f 00 00 00 jne 2ae <kmap_atomic_prot+0x1c7> 21f: 83 3d 00 00 00 00 02 cmpl $0x2,0x0 226: 0f 85 82 00 00 00 jne 2ae <kmap_atomic_prot+0x1c7> 22c: 64 a1 00 00 00 00 mov %fs:0x0,%eax [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/mmzone.h7
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 9f274a687c7..451eaa13bc2 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -637,9 +637,10 @@ static inline int is_normal_idx(enum zone_type idx)
static inline int is_highmem(struct zone *zone)
{
#ifdef CONFIG_HIGHMEM
- int zone_idx = zone - zone->zone_pgdat->node_zones;
- return zone_idx == ZONE_HIGHMEM ||
- (zone_idx == ZONE_MOVABLE && zone_movable_is_highmem());
+ int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
+ return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
+ (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
+ zone_movable_is_highmem());
#else
return 0;
#endif