From: Masami Hiramatsu <mhiramat@redhat.com>
Date: Fri, 6 Mar 2009 15:37:22 +0000 (-0500)
Subject: tracing, Text Edit Lock - SMP alternatives support
X-Git-Tag: v2.6.30-rc1~2^2~55^2~1
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=3945dab45aa8c89014893bfa8eb1e1661a409cef

tracing, Text Edit Lock - SMP alternatives support

Use the mutual exclusion provided by the text edit lock in alternatives code.
Since alternative_smp_* will be called from module init code, etc,
we'd better protect it from other subsystems.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <49B14332.9030109@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4c80f1557433..092a7b8be68d 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -5,6 +5,7 @@
 #include <linux/kprobes.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
+#include <linux/memory.h>
 #include <asm/alternative.h>
 #include <asm/sections.h>
 #include <asm/pgtable.h>
@@ -226,6 +227,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
 {
 	u8 **ptr;
 
+	mutex_lock(&text_mutex);
 	for (ptr = start; ptr < end; ptr++) {
 		if (*ptr < text)
 			continue;
@@ -234,6 +236,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
 		/* turn DS segment override prefix into lock prefix */
 		text_poke(*ptr, ((unsigned char []){0xf0}), 1);
 	};
+	mutex_unlock(&text_mutex);
 }
 
 static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end)
@@ -243,6 +246,7 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end
 	if (noreplace_smp)
 		return;
 
+	mutex_lock(&text_mutex);
 	for (ptr = start; ptr < end; ptr++) {
 		if (*ptr < text)
 			continue;
@@ -251,6 +255,7 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end
 		/* turn lock prefix into DS segment override prefix */
 		text_poke(*ptr, ((unsigned char []){0x3E}), 1);
 	};
+	mutex_unlock(&text_mutex);
 }
 
 struct smp_alt_module {