Messages in this thread | | | From | Song Shuai <> | Date | Wed, 23 Nov 2022 05:31:24 +0000 | Subject | Re: [PATCH] ftrace: Avoid needless updates of the ftrace function call |
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Steven Rostedt <rostedt@goodmis.org> 于2022年11月23日周三 03:17写道: > > On Wed, 23 Nov 2022 10:29:28 +0800 > Song Shuai <suagrfillet@gmail.com> wrote: > > > > @@ -2783,7 +2796,7 @@ void ftrace_modify_all_code(int command) > > > * traced. > > > */ > > > if (update) { > > > - err = ftrace_update_ftrace_func(ftrace_ops_list_func); > > > + err = update_ftrace_func(ftrace_ops_list_func); > > > if (FTRACE_WARN_ON(err)) > > > return; > > > } > > > @@ -2799,7 +2812,7 @@ void ftrace_modify_all_code(int command) > > > /* If irqs are disabled, we are in stop machine */ > > > if (!irqs_disabled()) > > > smp_call_function(ftrace_sync_ipi, NULL, 1); > > > - err = ftrace_update_ftrace_func(ftrace_trace_function); > > > + err = update_ftrace_func(ftrace_trace_function); > > The helper function should only serve the ftrace_ops_list_func. > > > > And ftrace_trace_function is always different in this function with > > FTRACE_UPDATE_TRACE_FUNC command. > > > > So this place should be left as it is. > > But it is needed to update the static variable. Without this change, > then save_func will get set to ftrace_ops_list_func and never change > after that and then the update to ftrace_ops_list_func will stop happening. > > -- Steve Yes, you're right. Thx for your explanation. -- Song
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