[for-linus][PATCH 0/2] fgraph: Fixes for 6.12

[for-linus][PATCH 0/2] fgraph: Fixes for 6.12

[Steven Rostedt]

Fixes for function graph:

- Fix missing mutex unlock in error path of register_ftrace_graph()

  A previous fix added a return on an error path and forgot to unlock the
  mutex. Instead of dealing with error paths, use guard(mutex) as the mutex
  is just released at the exit of the function anyway. Other functions
  in this file should be updated with this, but that's a cleanup and not
  a fix.

- Change cpuhp setup name to be consistent with other cpuhp states

  The same fix that the above patch fixes added a cpuhp_setup_state() call
  with the name of "fgraph_idle_init". I was informed that it should instead
  be something like: "fgraph:online". Update that too.

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
ftrace/fixes

Head SHA1: a574e7f80e86c740e241c762923f50077b2c2a30


Li Huafei (1):
      fgraph: Fix missing unlock in register_ftrace_graph()

Steven Rostedt (1):
      fgraph: Change the name of cpuhp state to "fgraph:online"

----
 kernel/trace/fgraph.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

[for-linus][PATCH 1/2] fgraph: Fix missing unlock in register_ftrace_graph()

[Steven Rostedt]

From: Li Huafei <lihuafei1@huawei.com>

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: 2c02f7375e65 ("fgraph: Use CPU hotplug mechanism to initialize idle shadow stacks")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202410220121.wxg0olfd-lkp@intel.com/
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/fgraph.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 41e7a15dcb50..cd1c2946018c 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -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;
 }
 
-- 
2.45.2

[for-linus][PATCH 2/2] fgraph: Change the name of cpuhp state to "fgraph:online"

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

The cpuhp state name given to cpuhp_setup_state() is "fgraph_idle_init"
which doesn't really conform to the names that are used for cpu hotplug
setups. Instead rename it to "fgraph:online" to be in line with other
states.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/20241024222944.473d88c5@rorschach.local.home
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 2c02f7375e658 ("fgraph: Use CPU hotplug mechanism to initialize idle shadow stacks")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 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 cd1c2946018c..69e226a48daa 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -1255,7 +1255,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
 	guard(mutex)(&ftrace_lock);
 
 	if (!fgraph_initialized) {
-		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph_idle_init",
+		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph:online",
 					fgraph_cpu_init, NULL);
 		if (ret < 0) {
 			pr_warn("fgraph: Error to init cpu hotplug support\n");
-- 
2.45.2