redonkable/alistair23-linux
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tracing, Text Edit Lock - SMP alternatives support

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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>
This commit is contained in:
Masami Hiramatsu 2009-03-06 10:37:22 -05:00 committed by Ingo Molnar
parent 4460fdad85
commit 3945dab45a
1 changed files with 5 additions and 0 deletions
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5
arch/x86/kernel/alternative.c
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@ -5,6 +5,7 @@
#include <linux/kprobes.h> #include <linux/kprobes.h>
#include <linux/mm.h> #include <linux/mm.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/memory.h>
#include <asm/alternative.h> #include <asm/alternative.h>
#include <asm/sections.h> #include <asm/sections.h>
#include <asm/pgtable.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; u8 **ptr;
mutex_lock(&text_mutex);
for (ptr = start; ptr < end; ptr++) { for (ptr = start; ptr < end; ptr++) {
if (*ptr < text) if (*ptr < text)
continue; 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 */ /* turn DS segment override prefix into lock prefix */
text_poke(*ptr, ((unsigned char []){0xf0}), 1); 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) 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) if (noreplace_smp)
return; return;
mutex_lock(&text_mutex);
for (ptr = start; ptr < end; ptr++) { for (ptr = start; ptr < end; ptr++) {
if (*ptr < text) if (*ptr < text)
continue; 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 */ /* turn lock prefix into DS segment override prefix */
text_poke(*ptr, ((unsigned char []){0x3E}), 1); text_poke(*ptr, ((unsigned char []){0x3E}), 1);
}; };
mutex_unlock(&text_mutex);
} }
struct smp_alt_module { struct smp_alt_module {