Commit bd3734db authored by Li Huafei's avatar Li Huafei Committed by Steven Rostedt (Google)
Browse files

fgraph: Fix missing unlock in register_ftrace_graph() 

Use guard(mutex)() to acquire and automatically release ftrace_lock,
fixing the issue of not unlocking when calling cpuhp_setup_state()
fails.

Fixes smatch warning:

kernel/trace/fgraph.c:1317 register_ftrace_graph() warn: inconsistent returns '&ftrace_lock'.

Link: https://lore.kernel.org/20241024155917.1019580-1-lihuafei1@huawei.com


Fixes: 2c02f737 ("fgraph: Use CPU hotplug mechanism to initialize idle shadow stacks")
Reported-by: default avatarkernel test robot <lkp@intel.com>
Reported-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202410220121.wxg0olfd-lkp@intel.com/


Suggested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarLi Huafei <lihuafei1@huawei.com>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent fae4078c

kernel/trace/fgraph.c

+3 −7
Original line number Diff line number Diff line
@@ -1252,7 +1252,7 @@ int register_ftrace_graph(struct fgraph_ops *gops) 
	int ret = 0;

	int i = -1;



	mutex_lock(&ftrace_lock);

	guard(mutex)(&ftrace_lock);



	if (!fgraph_initialized) {

		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph_idle_init",
@@ -1273,10 +1273,8 @@ int register_ftrace_graph(struct fgraph_ops *gops) 
	}



	i = fgraph_lru_alloc_index();

	if (i < 0 || WARN_ON_ONCE(fgraph_array[i] != &fgraph_stub)) {

		ret = -ENOSPC;

		goto out;

	}

	if (i < 0 || WARN_ON_ONCE(fgraph_array[i] != &fgraph_stub))

		return -ENOSPC;

	gops->idx = i;



	ftrace_graph_active++;
@@ -1313,8 +1311,6 @@ int register_ftrace_graph(struct fgraph_ops *gops) 
		gops->saved_func = NULL;

		fgraph_lru_release_index(i);

	}

out:

	mutex_unlock(&ftrace_lock);

	return ret;

}