On Thu, Feb 27, 2014 at 10:46:18AM -0500, Steven Rostedt wrote: > [Request for Ack] > > From: Petr Mladek <pmladek@xxxxxxx> > > 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. So IIUC the risk is that other CPUs may spuriously ignore non-ftrace traps if we don't sync the other cores after reverting the int3 before decrementing the modifying_ftrace_code counter? > > Link: http://lkml.kernel.org/r/1393258342-29978-2-git-send-email-pmladek@xxxxxxx > > Fixes: 8a4d0a687a5 "ftrace: Use breakpoint method to update ftrace caller" > Cc: stable@xxxxxxxxxxxxxxx # 3.5+ > Signed-off-by: Petr Mladek <pmladek@xxxxxxx> > Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> > --- > 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 6b566c8..69885e2 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: This could be further optimized by rather calling run_sync() in the end of the fail_update block (after the probe_kernel_write revert) otherwise even failure on setting the break will result in run_sync(), which doesn't appear to be needed. But that's really just nitpicking as it's a rare failure codepath and shouldn't hurt. In any case, the fix looks correct. Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> > -- > 1.8.5.3 > > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html