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fgraph: Fix missing unlock in register_ftrace_graph()

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BugLink: https://bugs.launchpad.net/bugs/2097575

[ Upstream commit bd3734db86e01e20dd239a40b419059a0ce9c901 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
This commit is contained in:
Li Huafei
2024-10-24 23:59:17 +08:00
committed by Stefan Bader
parent 29ce95fa11
commit fdaab63931
1 changed files with 4 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/trace/fgraph.c
+4 -8
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@@ -637,7 +637,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
static bool fgraph_initialized;
int ret = 0;
mutex_lock(&ftrace_lock);
guard(mutex)(&ftrace_lock);
if (!fgraph_initialized) {
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph_idle_init",
@@ -651,10 +651,8 @@ int register_ftrace_graph(struct fgraph_ops *gops)
}
/* we currently allow only one tracer registered at a time */
if (ftrace_graph_active) {
ret = -EBUSY;
goto out;
}
if (ftrace_graph_active)
return -EBUSY;
register_pm_notifier(&ftrace_suspend_notifier);
@@ -662,7 +660,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
ret = start_graph_tracing();
if (ret) {
ftrace_graph_active--;
goto out;
return ret;
}
ftrace_graph_return = gops->retfunc;
@@ -678,8 +676,6 @@ int register_ftrace_graph(struct fgraph_ops *gops)
update_function_graph_func();
ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
out:
mutex_unlock(&ftrace_lock);
return ret;
}