diff options
| author | Harvey Harrison <harvey.harrison@gmail.com> | 2008-04-28 02:12:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-28 08:58:17 -0700 |
| commit | ddc81ed2c5d47a078a3b02c5c3a4345bc2bc3c9b (patch) | |
| tree | 2bd3e56604350d05d5163e32dde7fbbe56d31586 | |
| parent | 488514d1798289f56f80ed018e246179fe500383 (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.h | 7 |
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 |