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 4c80f15..092a7b8 100644 (file)
--- 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 {