linux-kernel - [PATCH] ftrace/direct: Fix lockup in modify_ftrace_direct

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Message-Id: <20211109114217.1645296-1-jolsa@kernel.org>
Date:   Tue,  9 Nov 2021 12:42:17 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH] ftrace/direct: Fix lockup in modify_ftrace_direct_multi

We can't call unregister_ftrace_function under ftrace_lock.

Fixes: ed29271894aa ("ftrace/direct: Do not disable when switching direct callers")
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/trace/ftrace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b4ed1a301232..fc49e8809a56 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5602,10 +5602,11 @@ int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
 		}
 	}
 
+	mutex_unlock(&ftrace_lock);
+
 	/* Removing the tmp_ops will add the updated direct callers to the functions */
 	unregister_ftrace_function(&tmp_ops);
 
-	mutex_unlock(&ftrace_lock);
  out_direct:
 	mutex_unlock(&direct_mutex);
 	return err;
-- 
2.32.0