On Fri, 21 Feb 2014 17:33:52 +0100
Petr Mládek <pmla...@suse.cz> wrote:
> Yes, it works but I would still do few more changes:
>
> + run_sync() also in ftrace_modify_code() in the recovery
> part; I would solve this by moving the "out" label.
Sounds good.
>
> + print some warning in update_ftrace_func() when
> ftrace_modify_code() fails; otherwise, the error
> is silently ignored
The error is passed down to the callers. Any warning should happen
there. We can move that up to the generic code. Otherwise, this is a
x86 only fix, and we leave all the other archs broken.
ftrace_modify_all_code() looks to be where the warnings should be. And
yes, any warning should also call ftrace_bug(). That can be done via a
FTRACE_WARN_ON().
>
> + BUG when the breakpoint cannot be removed; the system
> silently crash anyway because the breakpoint will not
> be handled
>
> I wonder if we should call FTRACE_WARN_ON_ONCE that calls
> "ftrace_kill" when update_ftrace_func() fails.
Don't need the _ONCE() version. Something like this (I'll let you make
the patch ;-)
int ret = 0;
if (update)
ret = ftrace_update_ftrace_func(ftrace_ops_list_func);
if (ret)
goto out;
if (command & FTRACE_UPDATE_CALLS)
ret = ftrace_replace_code(1);
else if (command & FTRACE_DISABLE_CALLS)
ret = ftrace_replace_code(0);
if (ret)
goto out;
if (update && ftrace_trace_function != ftrace_ops_list_func) {
function_trace_op = set_function_trace_op;
smp_wmb();
/* If irqs are disabled, we are in stop machine */
if (!irqs_disabled())
smp_call_function(ftrace_sync_ipi, NULL, 1);
ret = ftrace_update_ftrace_func(ftrace_trace_function);
}
if (ret)
goto out;
if (command & FTRACE_START_FUNC_RET)
ret = ftrace_enable_ftrace_graph_caller();
else if (command & FTRACE_STOP_FUNC_RET)
ret = ftrace_disable_ftrace_graph_caller();
out:
FTRACE_WARN_ON(ret);
Or if you want to keep where it failed, just replace the if (ret) goto
out, with:
if (FTRACE_WARN_ON(ret))
return;
That may actually be better.
I've already added my patch. I'll push it up to my ftrace/urgent branch
at
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
And you can write a patch based on that.
Thanks!
-- Steve
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