ftrace: Fix synchronization location disabling and freeing ftrace_ops (a4c35ed2) · Commits · 戴 / test

kernel/trace/ftrace.c

+32 −26

Original line number	Original line	Diff line number	Diff line
	@@ -498,20 +498,6 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
	} else if (ops->flags & FTRACE_OPS_FL_CONTROL) {		} else if (ops->flags & FTRACE_OPS_FL_CONTROL) {
	ret = remove_ftrace_list_ops(&ftrace_control_list,		ret = remove_ftrace_list_ops(&ftrace_control_list,
	&control_ops, ops);		&control_ops, ops);
	if (!ret) {
	/*
	* The ftrace_ops is now removed from the list,
	* so there'll be no new users. We must ensure
	* all current users are done before we free
	* the control data.
	* Note synchronize_sched() is not enough, as we
	* use preempt_disable() to do RCU, but the function
	* tracer can be called where RCU is not active
	* (before user_exit()).
	*/
	schedule_on_each_cpu(ftrace_sync);
	control_ops_free(ops);
	}
	} else		} else
	ret = remove_ftrace_ops(&ftrace_ops_list, ops);		ret = remove_ftrace_ops(&ftrace_ops_list, ops);

	@@ -521,17 +507,6 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
	if (ftrace_enabled)		if (ftrace_enabled)
	update_ftrace_function();		update_ftrace_function();

	/*
	* Dynamic ops may be freed, we must make sure that all
	* callers are done before leaving this function.
	*
	* Again, normal synchronize_sched() is not good enough.
	* We need to do a hard force of sched synchronization.
	*/
	if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
	schedule_on_each_cpu(ftrace_sync);


	return 0;		return 0;
	}		}

	@@ -2208,10 +2183,41 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
	command \|= FTRACE_UPDATE_TRACE_FUNC;		command \|= FTRACE_UPDATE_TRACE_FUNC;
	}		}

	if (!command \|\| !ftrace_enabled)		if (!command \|\| !ftrace_enabled) {
			/*
			* If these are control ops, they still need their
			* per_cpu field freed. Since, function tracing is
			* not currently active, we can just free them
			* without synchronizing all CPUs.
			*/
			if (ops->flags & FTRACE_OPS_FL_CONTROL)
			control_ops_free(ops);
	return 0;		return 0;
			}

	ftrace_run_update_code(command);		ftrace_run_update_code(command);

			/*
			* Dynamic ops may be freed, we must make sure that all
			* callers are done before leaving this function.
			* The same goes for freeing the per_cpu data of the control
			* ops.
			*
			* Again, normal synchronize_sched() is not good enough.
			* We need to do a hard force of sched synchronization.
			* This is because we use preempt_disable() to do RCU, but
			* the function tracers can be called where RCU is not watching
			* (like before user_exit()). We can not rely on the RCU
			* infrastructure to do the synchronization, thus we must do it
			* ourselves.
			*/
			if (ops->flags & (FTRACE_OPS_FL_DYNAMIC \| FTRACE_OPS_FL_CONTROL)) {
			schedule_on_each_cpu(ftrace_sync);

			if (ops->flags & FTRACE_OPS_FL_CONTROL)
			control_ops_free(ops);
			}

	return 0;		return 0;
	}		}

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