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[PATCH -tip v2 2/2] x86: Issue at least one memory barrier in stop_machine_text_poke().
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: Ingo Molnar <mingo at elte dot hu>, lkml<linux-kernel at vger dot kernel dot org>
- Cc: systemtap<systemtap at sources dot redhat dot com>, DLE<dle-develop at lists dot sourceforge dot net>, Masami Hiramatsu <mhiramat at redhat dot com>, Mathieu Desnoyers <mathieu dot desnoyers at efficios dot com>, Ingo Molnar <mingo at elte dot hu>, Jason Baron <jbaron at redhat dot com>
- Date: Wed, 03 Mar 2010 22:38:50 -0500
- Subject: [PATCH -tip v2 2/2] x86: Issue at least one memory barrier in stop_machine_text_poke().
- References: <20100304033843.3819.10087.stgit@localhost6.localdomain6>
Fix stop_machine_text_poke() to issue smp_mb() before exiting waiting
loop, and use cpu_relax() for waiting.
Changes in v2:
- Don't use ACCESS_ONCE().
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
---
arch/x86/kernel/alternative.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 635e4f4..3a4bf35 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -597,8 +597,8 @@ static int __kprobes stop_machine_text_poke(void *data)
wrote_text = 1;
} else {
while (!wrote_text)
- smp_rmb();
- sync_core();
+ cpu_relax();
+ smp_mb(); /* Load wrote_text before following execution */
}
flush_icache_range((unsigned long)tpp->addr,
--
Masami Hiramatsu
e-mail: mhiramat@redhat.com