[PATCH] percpu data: only iterate over possible CPUs

percpu_data blindly allocates bootmem memory to store NR_CPUS instances of
cpudata, instead of allocating memory only for possible cpus.

As a preparation for changing that, we need to convert various 0 -> NR_CPUS
loops to use for_each_cpu().

(The above only applies to users of asm-generic/percpu.h.  powerpc has gone it
alone and is presently only allocating memory for present CPUs, so it's
currently corrupting memory).

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Jens Axboe <axboe@suse.de>
Cc: Anton Blanchard <anton@samba.org>
Acked-by: William Irwin <wli@holomorphy.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

11 files changed, 17 insertions, 16 deletions

diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index d661703ac1cb..63f39a7e2c96 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -138,7 +138,7 @@ static int __init check_nmi_watchdog(void)
         if (nmi_watchdog == NMI_LOCAL_APIC)
                 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
 
-        for (cpu = 0; cpu < NR_CPUS; cpu++)
+        for_each_cpu(cpu)
                 prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count;
         local_irq_enable();
         mdelay((10*1000)/nmi_hz); // wait 10 ticks
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index f9fc07efd2da..e5aad8314585 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3453,7 +3453,7 @@ int __init blk_dev_init(void)
         iocontext_cachep = kmem_cache_create("blkdev_ioc",
                         sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL);
 
-        for (i = 0; i < NR_CPUS; i++)
+        for_each_cpu(i)
                 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
 
         open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL);
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 245ca99a641e..c551bb84dbfb 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -1245,7 +1245,7 @@ static int __init init_scsi(void)
         if (error)
                 goto cleanup_sysctl;
 
-        for (i = 0; i < NR_CPUS; i++)
+        for_each_cpu(i)
                 INIT_LIST_HEAD(&per_cpu(scsi_done_q, i));
 
         devfs_mk_dir("scsi");
diff --git a/fs/file.c b/fs/file.c
index fd066b261c75..cea7cbea11d0 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -379,7 +379,6 @@ static void __devinit fdtable_defer_list_init(int cpu)
 void __init files_defer_init(void)
 {
         int i;
-        /* Really early - can't use for_each_cpu */
-        for (i = 0; i < NR_CPUS; i++)
+        for_each_cpu(i)
                 fdtable_defer_list_init(i);
 }
diff --git a/kernel/sched.c b/kernel/sched.c
index f77f23f8f479..839466fdfb4c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6109,7 +6109,7 @@ void __init sched_init(void)
         runqueue_t *rq;
         int i, j, k;
 
-        for (i = 0; i < NR_CPUS; i++) {
+        for_each_cpu(i) {
                 prio_array_t *array;
 
                 rq = cpu_rq(i);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 44b4eb4202d9..dde04ff4be31 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1213,18 +1213,21 @@ static void __get_page_state(struct page_state *ret, int nr, cpumask_t *cpumask)
 {
         int cpu = 0;
 
-        memset(ret, 0, sizeof(*ret));
+        memset(ret, 0, nr * sizeof(unsigned long));
         cpus_and(*cpumask, *cpumask, cpu_online_map);
 
         cpu = first_cpu(*cpumask);
         while (cpu < NR_CPUS) {
                 unsigned long *in, *out, off;
 
+                if (!cpu_isset(cpu, *cpumask))
+                        continue;
+
                 in = (unsigned long *)&per_cpu(page_states, cpu);
 
                 cpu = next_cpu(cpu, *cpumask);
 
-                if (cpu < NR_CPUS)
+                if (likely(cpu < NR_CPUS))
                         prefetch(&per_cpu(page_states, cpu));
 
                 out = (unsigned long *)ret;
@@ -1886,8 +1889,7 @@ static void setup_pagelist_highmark(struct per_cpu_pageset *p,
  * not check if the processor is online before following the pageset pointer.
  * Other parts of the kernel may not check if the zone is available.
  */
-static struct per_cpu_pageset
-        boot_pageset[NR_CPUS];
+static struct per_cpu_pageset boot_pageset[NR_CPUS];
 
 /*
  * Dynamically allocate memory for the
diff --git a/net/core/dev.c b/net/core/dev.c
index ffb82073056e..2afb0de95329 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3237,7 +3237,7 @@ static int __init net_dev_init(void)
          *      Initialise the packet receive queues.
          */
 
-        for (i = 0; i < NR_CPUS; i++) {
+        for_each_cpu(i) {
                 struct softnet_data *queue;
 
                 queue = &per_cpu(softnet_data, i);
diff --git a/net/core/utils.c b/net/core/utils.c
index ac1d1fcf8673..fdc4f38bc46c 100644
--- a/net/core/utils.c
+++ b/net/core/utils.c
@@ -121,7 +121,7 @@ void __init net_random_init(void)
 {
         int i;
 
-        for (i = 0; i < NR_CPUS; i++) {
+        for_each_cpu(i) {
                 struct nrnd_state *state = &per_cpu(net_rand_state,i);
                 __net_srandom(state, i+jiffies);
         }
@@ -133,7 +133,7 @@ static int net_random_reseed(void)
         unsigned long seed[NR_CPUS];
 
         get_random_bytes(seed, sizeof(seed));
-        for (i = 0; i < NR_CPUS; i++) {
+        for_each_cpu(i) {
                 struct nrnd_state *state = &per_cpu(net_rand_state,i);
                 __net_srandom(state, seed[i]);
         }
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 39d49dc333a7..1b167c4bb3be 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -49,7 +49,7 @@ static int fold_prot_inuse(struct proto *proto)
         int res = 0;
         int cpu;
 
-        for (cpu = 0; cpu < NR_CPUS; cpu++)
+        for_each_cpu(cpu)
                 res += proto->stats[cpu].inuse;
 
         return res;
diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index 50a13e75d70e..4238b1ed8860 100644
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -38,7 +38,7 @@ static int fold_prot_inuse(struct proto *proto)
         int res = 0;
         int cpu;
 
-        for (cpu=0; cpu<NR_CPUS; cpu++)
+        for_each_cpu(cpu)
                 res += proto->stats[cpu].inuse;
 
         return res;
diff --git a/net/socket.c b/net/socket.c
index b38a263853c3..a00851f981db 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2078,7 +2078,7 @@ void socket_seq_show(struct seq_file *seq)
         int cpu;
         int counter = 0;
 
-        for (cpu = 0; cpu < NR_CPUS; cpu++)
+        for_each_cpu(cpu)
                 counter += per_cpu(sockets_in_use, cpu);
 
         /* It can be negative, by the way. 8) */