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Subject[PATCH -tip 3/4]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>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/alternative.c | 5 +++++
1 file changed, 5 insertions(+)

Index: 2.6.29-rc7/arch/x86/kernel/alternative.c
===================================================================
--- 2.6.29-rc7.orig/arch/x86/kernel/alternative.c
+++ 2.6.29-rc7/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 **s
{
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 **s
/* 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 *
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 *
/* turn lock prefix into DS segment override prefix */
text_poke(*ptr, ((unsigned char []){0x3E}), 1);
};
+ mutex_unlock(&text_mutex);
}

struct smp_alt_module {
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com



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