[PATCH -tip 2/2] x86: Issue at least one memory barrier in stop_machine_text_poke().
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From: Masami Hiramatsu on 3 Mar 2010 16:30 Fix stop_machine_text_poke() to issue smp_mb() before exiting waiting loop. Also, use ACCESS_ONCE() to check a flag according to Mathieu's comment. Signed-off-by: Masami Hiramatsu <mhiramat(a)redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Ingo Molnar <mingo(a)elte.hu> Cc: Jason Baron <jbaron(a)redhat.com> --- arch/x86/kernel/alternative.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 635e4f4..3236a11 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -596,9 +596,9 @@ static int __kprobes stop_machine_text_poke(void *data) smp_wmb(); /* Make sure other cpus see that this has run */ wrote_text = 1; } else { - while (!wrote_text) - smp_rmb(); - sync_core(); + while (!ACCESS_ONCE(wrote_text)) + cpu_relax(); + smp_mb(); /* Load wrote_text before following execution */ } flush_icache_range((unsigned long)tpp->addr, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat(a)redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |