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fgraph: Fix missing unlock in register_ftrace_graph()

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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>
This commit is contained in:
Li Huafei 2024-10-24 23:59:17 +08:00 committed by Steven Rostedt (Google)
parent fae4078c28
commit bd3734db86
1 changed files with 3 additions and 7 deletions
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10
kernel/trace/fgraph.c
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@ -1252,7 +1252,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
int ret = 0; int ret = 0;
int i = -1; int i = -1;
mutex_lock(&ftrace_lock); guard(mutex)(&ftrace_lock);
if (!fgraph_initialized) { if (!fgraph_initialized) {
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph_idle_init", 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(); i = fgraph_lru_alloc_index();
if (i < 0 || WARN_ON_ONCE(fgraph_array[i] != &fgraph_stub)) { if (i < 0 || WARN_ON_ONCE(fgraph_array[i] != &fgraph_stub))
ret = -ENOSPC; return -ENOSPC;
goto out;
}
gops->idx = i; gops->idx = i;
ftrace_graph_active++; ftrace_graph_active++;
@ -1313,8 +1311,6 @@ error:
gops->saved_func = NULL; gops->saved_func = NULL;
fgraph_lru_release_index(i); fgraph_lru_release_index(i);
} }
out:
mutex_unlock(&ftrace_lock);
return ret; return ret;
} }