linux-kernel - [PATCH v2 2/5] audit: account backlog waiting time in audit

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Message-Id: <20230511052116.19452-3-eiichi.tsukata@nutanix.com>
Date:   Thu, 11 May 2023 05:21:13 +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 2/5] audit: account backlog waiting time in audit_receive()

Currently backlog waiting time in audit_receive() is not accounted as
audit_backlog_wait_time_actual. Accounts it as well.

Signed-off-by: Eiichi Tsukata <eiichi.tsukata@...anix.com>
---
 kernel/audit.c | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index c15694e1a76b..89e119ccda76 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -628,6 +628,29 @@ static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
 	kfree_skb(skb);
 }
 
+/**
+ * wait_for_kauditd - Wait for kauditd to drain the queue
+ * @stime: time to sleep
+ *
+ * Description:
+ * Waits for kauditd to drain the queue then adds duration of sleep time to
+ * audit_backlog_wait_time_actual as cumulative sum.
+ * Returns remaining time to sleep.
+ */
+static long wait_for_kauditd(long stime)
+{
+	long rtime;
+	DECLARE_WAITQUEUE(wait, current);
+
+	add_wait_queue_exclusive(&audit_backlog_wait, &wait);
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	rtime = schedule_timeout(stime);
+	atomic_add(stime - rtime, &audit_backlog_wait_time_actual);
+	remove_wait_queue(&audit_backlog_wait, &wait);
+
+	return rtime;
+}
+
 /**
  * auditd_reset - Disconnect the auditd connection
  * @ac: auditd connection state
@@ -1568,15 +1591,9 @@ static void audit_receive(struct sk_buff  *skb)
 
 	/* can't block with the ctrl lock, so penalize the sender now */
 	if (audit_queue_full(&audit_queue)) {
-		DECLARE_WAITQUEUE(wait, current);
-
 		/* wake kauditd to try and flush the queue */
 		wake_up_interruptible(&kauditd_wait);
-
-		add_wait_queue_exclusive(&audit_backlog_wait, &wait);
-		set_current_state(TASK_UNINTERRUPTIBLE);
-		schedule_timeout(audit_backlog_wait_time);
-		remove_wait_queue(&audit_backlog_wait, &wait);
+		wait_for_kauditd(audit_backlog_wait_time);
 	}
 }
 
@@ -1874,17 +1891,8 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 
 			/* sleep if we are allowed and we haven't exhausted our
 			 * backlog wait limit */
-			if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
-				long rtime = stime;
-
-				DECLARE_WAITQUEUE(wait, current);
-
-				add_wait_queue_exclusive(&audit_backlog_wait,
-							 &wait);
-				set_current_state(TASK_UNINTERRUPTIBLE);
-				stime = schedule_timeout(rtime);
-				atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
-				remove_wait_queue(&audit_backlog_wait, &wait);
+			if (gfpflags_allow_blocking(gfp_mask) && stime > 0) {
+				stime = wait_for_kauditd(stime);
 			} else {
 				if (audit_rate_check() && printk_ratelimit())
 					pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
-- 
2.40.0