linux-kernel - [PATCH 1/3] ftrace: Use direct_ops hash in unregister_ftrace

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Date:   Mon,  6 Dec 2021 19:20:30 +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>,
        Heiko Carstens <hca@...ux.ibm.com>
Subject: [PATCH 1/3] ftrace: Use direct_ops hash in unregister_ftrace_direct

Now when we have *direct_multi interface the direct_functions
hash is no longer owned just by direct_ops. It's also used by
any other ftrace_ops passed to *direct_multi interface.

Thus to find out that we are unregistering the last function
from direct_ops, we need to check directly direct_ops's hash.

Fixes: f64dd4627ec6 ("ftrace: Add multi direct register/unregister interface")
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/trace/ftrace.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 30bc880c3849..7f0594e28226 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5217,6 +5217,7 @@ int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
 {
 	struct ftrace_direct_func *direct;
 	struct ftrace_func_entry *entry;
+	struct ftrace_hash *hash;
 	int ret = -ENODEV;
 
 	mutex_lock(&direct_mutex);
@@ -5225,7 +5226,8 @@ int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
 	if (!entry)
 		goto out_unlock;
 
-	if (direct_functions->count == 1)
+	hash = direct_ops.func_hash->filter_hash;
+	if (hash->count == 1)
 		unregister_ftrace_function(&direct_ops);
 
 	ret = ftrace_set_filter_ip(&direct_ops, ip, 1, 0);
-- 
2.33.1