path: root/init
diff options
authorEric Dumazet <dada1@cosmosbay.com>2006-03-23 03:01:07 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-23 07:38:17 -0800
commitb73b459f72f746a031d1ef4cc7659b20a1f1acb9 (patch)
tree6e8d58fb0bd01e0a2c24c4debdffd9eb6719a384 /init
parent394e3902c55e667945f6f1c2bdbc59842cce70f7 (diff)
Now CONFIG_DEBUG_INITDATA is in, initial percpu data [__per_cpu_start,__per_cpu_end] can be declared as a redzone, and invalid accesses after boot can be detected, at least for i386. We can let non possible cpus percpu data point to this 'redzone' instead of NULL . NULL was not a good choice because part of [0..32768] memory may be readable and invalid accesses may happen unnoticed. If CONFIG_DEBUG_INITDATA is not defined, each non possible cpu points to the initial percpu data (__per_cpu_offset[cpu] == 0), thus invalid accesses wont be detected/crash. This patch also moves __per_cpu_offset[] to read_mostly area to avoid false sharing. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'init')
1 files changed, 2 insertions, 6 deletions
diff --git a/init/main.c b/init/main.c
index 9cf6b307bfd..2714e0e7cfe 100644
--- a/init/main.c
+++ b/init/main.c
@@ -325,7 +325,7 @@ static inline void smp_prepare_cpus(unsigned int maxcpus) { }
-unsigned long __per_cpu_offset[NR_CPUS];
+unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
@@ -343,11 +343,7 @@ static void __init setup_per_cpu_areas(void)
ptr = alloc_bootmem(size * nr_possible_cpus);
- for (i = 0; i < NR_CPUS; i++) {
- if (!cpu_possible(i)) {
- __per_cpu_offset[i] = (char*)0 - __per_cpu_start;
- continue;
- }
+ for_each_cpu(i) {
__per_cpu_offset[i] = ptr - __per_cpu_start;
memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
ptr += size;