[PATCH] more for_each_cpu() conversions

When we stop allocating percpu memory for not-possible CPUs we must not touch
the percpu data for not-possible CPUs at all.  The correct way of doing this
is to test cpu_possible() or to use for_each_cpu().

This patch is a kernel-wide sweep of all instances of NR_CPUS.  I found very
few instances of this bug, if any.  But the patch converts lots of open-coded
test to use the preferred helper macros.

Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Kyle McMartin <kyle@parisc-linux.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Christian Zankel <chris@zankel.net>
Cc: Philippe Elie <phil.el@wanadoo.fr>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 3 insertions, 7 deletions

diff --git a/fs/xfs/linux-2.6/xfs_stats.c b/fs/xfs/linux-2.6/xfs_stats.c
index 8955720a2c6b..713e6a7505d0 100644
--- a/fs/xfs/linux-2.6/xfs_stats.c
+++ b/fs/xfs/linux-2.6/xfs_stats.c
@@ -62,18 +62,15 @@ xfs_read_xfsstats(
                 while (j < xstats[i].endpoint) {
                         val = 0;
                         /* sum over all cpus */
-                        for (c = 0; c < NR_CPUS; c++) {
-                                if (!cpu_possible(c)) continue;
+                        for_each_cpu(c)
                                 val += *(((__u32*)&per_cpu(xfsstats, c) + j));
-                        }
                         len += sprintf(buffer + len, " %u", val);
                         j++;
                 }
                 buffer[len++] = '\n';
         }
         /* extra precision counters */
-        for (i = 0; i < NR_CPUS; i++) {
-                if (!cpu_possible(i)) continue;
+        for_each_cpu(i) {
                 xs_xstrat_bytes += per_cpu(xfsstats, i).xs_xstrat_bytes;
                 xs_write_bytes += per_cpu(xfsstats, i).xs_write_bytes;
                 xs_read_bytes += per_cpu(xfsstats, i).xs_read_bytes;
diff --git a/fs/xfs/linux-2.6/xfs_sysctl.c b/fs/xfs/linux-2.6/xfs_sysctl.c
index a02564972420..7079cc837210 100644
--- a/fs/xfs/linux-2.6/xfs_sysctl.c
+++ b/fs/xfs/linux-2.6/xfs_sysctl.c
@@ -38,8 +38,7 @@ xfs_stats_clear_proc_handler(
 
         if (!ret && write && *valp) {
                 printk("XFS Clearing xfsstats\n");
-                for (c = 0; c < NR_CPUS; c++) {
-                        if (!cpu_possible(c)) continue;
+                for_each_cpu(c) {
                         preempt_disable();
                         /* save vn_active, it's a universal truth! */
                         vn_active = per_cpu(xfsstats, c).vn_active;