From d5b18ed1dff8d3cf90e42981ffb54f5d4a4982f8 Mon Sep 17 00:00:00 2001 From: Petr Mladek Date: Mon, 24 Feb 2014 17:12:20 +0100 Subject: [PATCH] ftrace/x86: One more missing sync after fixup of function modification failure commit 12729f14d8357fb845d75155228b21e76360272d upstream. If a failure occurs while modifying ftrace function, it bails out and will remove the tracepoints to be back to what the code originally was. There is missing the final sync run across the CPUs after the fix up is done and before the ftrace int3 handler flag is reset. Here's the description of the problem: CPU0 CPU1 ---- ---- remove_breakpoint(); modifying_ftrace_code = 0; [still sees breakpoint] [sees modifying_ftrace_code as zero] [no breakpoint handler] [goto failed case] [trap exception - kernel breakpoint, no handler] BUG() Link: http://lkml.kernel.org/r/1393258342-29978-2-git-send-email-pmladek@suse.cz Fixes: 8a4d0a687a5 "ftrace: Use breakpoint method to update ftrace caller" Acked-by: Frederic Weisbecker Acked-by: H. Peter Anvin Signed-off-by: Petr Mladek Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index e625319..1ffc32d 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -659,8 +659,8 @@ ftrace_modify_code(unsigned long ip, unsigned const char *old_code, ret = -EPERM; goto out; } - run_sync(); out: + run_sync(); return ret; fail_update: -- 2.7.4