netdev - [RFC bpf-next 03/16] ftrace: Add get/put_direct

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Date:   Thu, 22 Oct 2020 10:21:25 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>, Daniel Xu <dxu@...uu.xyz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Jesper Brouer <jbrouer@...hat.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Viktor Malik <vmalik@...hat.com>
Subject: [RFC bpf-next 03/16] ftrace: Add get/put_direct_func function

Move code for managing ftrace_direct_funcs entries
into get_direct_func and put_direct_func functions.
It will be used in following patches, there's no
functional change.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/trace/ftrace.c | 44 +++++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index cb8b7a66c6af..95ef7e2a6a57 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5076,6 +5076,32 @@ static int adjust_direct_size(int new_size, struct ftrace_hash **free_hash)
 	return 0;
 }
 
+static struct ftrace_direct_func *get_direct_func(unsigned long addr)
+{
+	struct ftrace_direct_func *direct;
+
+	direct = ftrace_find_direct_func(addr);
+	if (!direct) {
+		direct = kmalloc(sizeof(*direct), GFP_KERNEL);
+		if (!direct)
+			return NULL;
+		direct->addr = addr;
+		direct->count = 0;
+		list_add_rcu(&direct->next, &ftrace_direct_funcs);
+		ftrace_direct_func_count++;
+	}
+
+	return direct;
+}
+
+static void put_direct_func(struct ftrace_direct_func *direct)
+{
+	list_del_rcu(&direct->next);
+	synchronize_rcu_tasks();
+	kfree(direct);
+	ftrace_direct_func_count--;
+}
+
 /**
  * register_ftrace_direct - Call a custom trampoline directly
  * @ip: The address of the nop at the beginning of a function
@@ -5114,17 +5140,10 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr)
 	if (!entry)
 		goto out_unlock;
 
-	direct = ftrace_find_direct_func(addr);
+	direct = get_direct_func(addr);
 	if (!direct) {
-		direct = kmalloc(sizeof(*direct), GFP_KERNEL);
-		if (!direct) {
-			kfree(entry);
-			goto out_unlock;
-		}
-		direct->addr = addr;
-		direct->count = 0;
-		list_add_rcu(&direct->next, &ftrace_direct_funcs);
-		ftrace_direct_func_count++;
+		kfree(entry);
+		goto out_unlock;
 	}
 
 	entry->ip = ip;
@@ -5144,13 +5163,10 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr)
 	if (ret) {
 		kfree(entry);
 		if (!direct->count) {
-			list_del_rcu(&direct->next);
-			synchronize_rcu_tasks();
-			kfree(direct);
+			put_direct_func(direct);
 			if (free_hash)
 				free_ftrace_hash(free_hash);
 			free_hash = NULL;
-			ftrace_direct_func_count--;
 		}
 	} else {
 		direct->count++;
-- 
2.26.2