3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Petr Mladek <[email protected]> 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] <takes trap> [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/[email protected] Fixes: 8a4d0a687a5 "ftrace: Use breakpoint method to update ftrace caller" Acked-by: Frederic Weisbecker <[email protected]> Acked-by: H. Peter Anvin <[email protected]> Signed-off-by: Petr Mladek <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -659,8 +659,8 @@ ftrace_modify_code(unsigned long ip, uns ret = -EPERM; goto out; } - run_sync(); out: + run_sync(); return ret; fail_update: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
