From: Petr Mladek Date: Mon, 24 Feb 2014 16:12:20 +0000 (+0100) Subject: ftrace/x86: One more missing sync after fixup of function modification failure X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=12729f14d8357fb845d75155228b21e76360272d;p=deliverable%2Flinux.git ftrace/x86: One more missing sync after fixup of function modification failure 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 --- diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 6b566c82d82c..69885e2f2095 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -660,8 +660,8 @@ ftrace_modify_code(unsigned long ip, unsigned const char *old_code, ret = -EPERM; goto out; } - run_sync(); out: + run_sync(); return ret; fail_update: