linux-kernel - [PATCH 06/16] SPARC: use ACCESS

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Date:	Wed, 18 Nov 2009 15:51:52 +0100
From:	Jiri Slaby <jslaby@...ell.com>
To:	jirislaby@...il.com
Cc:	mingo@...e.hu, nhorman@...driver.com, sfr@...b.auug.org.au,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	marcin.slusarz@...il.com, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, torvalds@...ux-foundation.org,
	Jiri Slaby <jslaby@...ell.com>,
	James Morris <jmorris@...ei.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	"David S. Miller" <davem@...emloft.net>, sparclinux@...r.kernel.org
Subject: [PATCH 06/16] SPARC: use ACCESS_ONCE for rlimits

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@...ell.com>
Cc: James Morris <jmorris@...ei.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: sparclinux@...r.kernel.org
---
 arch/sparc/kernel/sys_sparc_64.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index e2d1024..004ed47 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -361,6 +361,7 @@ EXPORT_SYMBOL(get_fb_unmapped_area);
 void arch_pick_mmap_layout(struct mm_struct *mm)
 {
 	unsigned long random_factor = 0UL;
+	unsigned long gap;
 
 	if (current->flags & PF_RANDOMIZE) {
 		random_factor = get_random_int();
@@ -375,9 +376,10 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 	 * Fall back to the standard layout if the personality
 	 * bit is set, or if the expected stack growth is unlimited:
 	 */
+	gap = ACCESS_ONCE(current->signal->rlim[RLIMIT_STACK].rlim_cur);
 	if (!test_thread_flag(TIF_32BIT) ||
 	    (current->personality & ADDR_COMPAT_LAYOUT) ||
-	    current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY ||
+	    gap == RLIM_INFINITY ||
 	    sysctl_legacy_va_layout) {
 		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
 		mm->get_unmapped_area = arch_get_unmapped_area;
@@ -385,9 +387,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 	} else {
 		/* We know it's 32-bit */
 		unsigned long task_size = STACK_TOP32;
-		unsigned long gap;
 
-		gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
 		if (gap < 128 * 1024 * 1024)
 			gap = 128 * 1024 * 1024;
 		if (gap > (task_size / 6 * 5))
-- 
1.6.4.2

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