linux-kernel - [-mm patch] enforce noreplace-smp in alternative

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Date:	Wed, 22 Aug 2007 22:25:51 +0200
From:	Frederik Deweerdt <deweerdt@...e.fr>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, jeremy@...p.org
Subject: [-mm patch] enforce noreplace-smp in alternative_instructions()

On Wed, Aug 22, 2007 at 02:06:48AM -0700, Andrew Morton wrote:
> 
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.23-rc3/2.6.23-rc3-mm1/
> 
Hi Jeremy,

arch/i386/kernel/alternative.c:alternative_instructions() doesn't
check for noreplace-smp before setting capability bits and freeing the
__smp_locks section.

Every call to alternatives_smp_unlock() checks for noreplace-smp
beforehand, so remove the check from there.

Boot tested on i386 with UP+noreplace-smp (lguest) and SMP (real hardware)

Regards,
Frederik

Signed-off-by: Frederik Deweerdt <frederik.deweerdt@...il.com>

diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 9f4ac8b..7c5af80 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -221,9 +221,6 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end
 	u8 **ptr;
 	char insn[1];
 
-	if (noreplace_smp)
-		return;
-
 	add_nops(insn, 1);
 	for (ptr = start; ptr < end; ptr++) {
 		if (*ptr < text)
@@ -406,7 +403,7 @@ void __init alternative_instructions(void)
 #endif
 
 #ifdef CONFIG_SMP
-	if (smp_alt_once) {
+	if (smp_alt_once && !noreplace_smp) {
 		if (1 == num_possible_cpus()) {
 			printk(KERN_INFO "SMP alternatives: switching to UP code\n");
 			set_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability);
-
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