linux-kernel - [PATCH v2 2/2] audit: replace auditd_conn.pid with auditd

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Date:   Tue, 18 Apr 2023 11:09:19 +0000
From:   Eiichi Tsukata <eiichi.tsukata@...anix.com>
To:     paul@...l-moore.com, eparis@...hat.com,
        linux-kernel@...r.kernel.org, audit@...r.kernel.org
Cc:     Eiichi Tsukata <eiichi.tsukata@...anix.com>
Subject: [PATCH v2 2/2] audit: replace auditd_conn.pid with auditd_pid

auditd_conn.pid is redundant. Replace it with auditd_pid.

Signed-off-by: Eiichi Tsukata <eiichi.tsukata@...anix.com>
---
 kernel/audit.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 9426980368e4..72a7397eaa89 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -94,7 +94,6 @@ struct audit_net {
 
 /**
  * struct auditd_connection - kernel/auditd connection state
- * @pid: auditd PID
  * @portid: netlink portid
  * @net: the associated network namespace
  * @rcu: RCU head
@@ -104,7 +103,6 @@ struct audit_net {
  * or the associated spinlock for writing.
  */
 struct auditd_connection {
-	struct pid *pid;
 	u32 portid;
 	struct net *net;
 	struct rcu_head rcu;
@@ -248,15 +246,11 @@ static bool audit_ctl_owner_current(void)
 static pid_t auditd_pid_vnr(void)
 {
 	pid_t pid;
-	const struct auditd_connection *ac;
+	unsigned long flags;
 
-	rcu_read_lock();
-	ac = rcu_dereference(auditd_conn);
-	if (!ac || !ac->pid)
-		pid = 0;
-	else
-		pid = pid_vnr(ac->pid);
-	rcu_read_unlock();
+	spin_lock_irqsave(&auditd_conn_lock, flags);
+	pid = auditd_pid ? pid_vnr(auditd_pid) : 0;
+	spin_unlock_irqrestore(&auditd_conn_lock, flags);
 
 	return pid;
 }
@@ -459,7 +453,6 @@ static void auditd_conn_free(struct rcu_head *rcu)
 	struct auditd_connection *ac;
 
 	ac = container_of(rcu, struct auditd_connection, rcu);
-	put_pid(ac->pid);
 	put_net(ac->net);
 	kfree(ac);
 }
@@ -478,6 +471,7 @@ static int auditd_set(struct pid *pid, u32 portid, struct net *net)
 {
 	unsigned long flags;
 	struct auditd_connection *ac_old, *ac_new;
+	struct pid *auditd_pid_old;
 
 	if (!pid || !net)
 		return -EINVAL;
@@ -485,7 +479,6 @@ static int auditd_set(struct pid *pid, u32 portid, struct net *net)
 	ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
 	if (!ac_new)
 		return -ENOMEM;
-	ac_new->pid = get_pid(pid);
 	ac_new->portid = portid;
 	ac_new->net = get_net(net);
 
@@ -493,9 +486,11 @@ static int auditd_set(struct pid *pid, u32 portid, struct net *net)
 	ac_old = rcu_dereference_protected(auditd_conn,
 					   lockdep_is_held(&auditd_conn_lock));
 	rcu_assign_pointer(auditd_conn, ac_new);
-	WRITE_ONCE(auditd_pid, ac_new->pid);
+	auditd_pid_old = auditd_pid;
+	WRITE_ONCE(auditd_pid, get_pid(pid));
 	spin_unlock_irqrestore(&auditd_conn_lock, flags);
 
+	put_pid(auditd_pid_old);
 	if (ac_old)
 		call_rcu(&ac_old->rcu, auditd_conn_free);
 
@@ -623,6 +618,7 @@ static void auditd_reset(const struct auditd_connection *ac)
 	unsigned long flags;
 	struct sk_buff *skb;
 	struct auditd_connection *ac_old;
+	struct pid *auditd_pid_old;
 
 	/* if it isn't already broken, break the connection */
 	spin_lock_irqsave(&auditd_conn_lock, flags);
@@ -634,9 +630,11 @@ static void auditd_reset(const struct auditd_connection *ac)
 		return;
 	}
 	rcu_assign_pointer(auditd_conn, NULL);
+	auditd_pid_old = auditd_pid;
 	WRITE_ONCE(auditd_pid, NULL);
 	spin_unlock_irqrestore(&auditd_conn_lock, flags);
 
+	put_pid(auditd_pid_old);
 	if (ac_old)
 		call_rcu(&ac_old->rcu, auditd_conn_free);
 
-- 
2.39.2