[PATCH 04/16] PPC: use ACCESS_ONCE for rlimits

[Jiri Slaby]

Make sure compiler won't do weird things with limits. E.g. fetching
them twice may return 2 different values after writable limits are
implemented.

Signed-off-by: Jiri Slaby <jslaby at novell.com>
Cc: James Morris <jmorris at namei.org>
Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Ingo Molnar <mingo at elte.hu>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Paul Mackerras <paulus at samba.org>
Cc: linuxppc-dev at ozlabs.org
---
 arch/powerpc/mm/mmap_64.c                    |    6 ++++--
 arch/powerpc/platforms/cell/spufs/coredump.c |    3 ++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/mmap_64.c b/arch/powerpc/mm/mmap_64.c
index 0d957a4..e96a5f6 100644
--- a/arch/powerpc/mm/mmap_64.c
+++ b/arch/powerpc/mm/mmap_64.c
@@ -47,7 +47,8 @@ static inline int mmap_is_legacy(void)
 	if (current->personality & ADDR_COMPAT_LAYOUT)
 		return 1;
 
-	if (current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY)
+	if (ACCESS_ONCE(current->signal->rlim[RLIMIT_STACK].rlim_cur) ==
+			RLIM_INFINITY)
 		return 1;
 
 	return sysctl_legacy_va_layout;
@@ -77,7 +78,8 @@ static unsigned long mmap_rnd(void)
 
 static inline unsigned long mmap_base(void)
 {
-	unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
+	unsigned long gap = ACCESS_ONCE(current->signal->
+			rlim[RLIMIT_STACK].rlim_cur);
 
 	if (gap < MIN_GAP)
 		gap = MIN_GAP;
diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index c4d4a19..2abf290 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -54,7 +54,8 @@ static ssize_t do_coredump_read(int num, struct spu_context *ctx, void *buffer,
  */
 static int spufs_dump_write(struct file *file, const void *addr, int nr, loff_t *foffset)
 {
-	unsigned long limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
+	unsigned long limit = ACCESS_ONCE(current->signal->
+			rlim[RLIMIT_CORE].rlim_cur);
 	ssize_t written;
 
 	if (*foffset + nr > limit)
-- 
1.6.4.2