Hi Steve,

On 2024/10/23 17:29, Steven Rostedt wrote:

On Thu, 24 Oct 2024 01:04:48 +0800
Li Huafei [off-list ref] wrote:

quoted

Instead of returning an error, goto the mutex unlock at the end of the
function.

Fixes smatch warning:

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

Fixes: 2c02f7375e65 ("fgraph: Use CPU hotplug mechanism to initialize idle shadow stacks")
Reported-by: kernel test robot <redacted>
Reported-by: Dan Carpenter <redacted>
Closes: https://lore.kernel.org/r/202410220121.wxg0olfd-lkp@intel.com/ (local)
Signed-off-by: Li Huafei <redacted>
---
 kernel/trace/fgraph.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 41e7a15dcb50..98fa7b2a4903 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c

@@ -1259,7 +1259,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
 					fgraph_cpu_init, NULL);
 		if (ret < 0) {
 			pr_warn("fgraph: Error to init cpu hotplug support\n");
-			return ret;
+			goto out;
 		}
 		fgraph_initialized = true;
 		ret = 0;

Actually, I'm thinking we just should use guard(mutex)(&ftrace_lock);

Agreed, this will make the code simpler and avoid mistakes. If we need
to replace all mutex(&ftrace_lock), would it be better to submit another
cleanup patch? We can fix the issue here first.

Thanks,
Huafei

-- Steve

.