From 7ecf69bf50fd3464342cab59fe08533fbe3f6076 Mon Sep 17 00:00:00 2001 From: Dan Duval Date: Mon, 16 Sep 2013 11:16:35 -0400 Subject: [PATCH] audit: efficiency fix 2: request exclusive wait since all need same resource These and similar errors were seen on a patched 3.8 kernel when the audit subsystem was overrun during boot: udevd[876]: worker [887] unexpectedly returned with status 0x0100 udevd[876]: worker [887] failed while handling '/devices/pci0000:00/0000:00:03.0/0000:40:00.0' udevd[876]: worker [880] unexpectedly returned with status 0x0100 udevd[876]: worker [880] failed while handling '/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1' udevadm settle - timeout of 180 seconds reached, the event queue contains: /sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1 (3995) /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/INT3F0D:00 (4034) audit: audit_backlog=258 > audit_backlog_limit=256 audit: audit_lost=1 audit_rate_limit=0 audit_backlog_limit=256 The change below increases the efficiency of the audit code and prevents it from being overrun: Use add_wait_queue_exclusive() in wait_for_auditd() to put the thread on the wait queue. When kauditd dequeues an skb, all of the waiting threads are waiting for the same resource, but only one is going to get it, so there's no need to wake up more than one waiter. See: https://lkml.org/lkml/2013/9/2/479 Signed-off-by: Dan Duval Signed-off-by: Chuck Anderson Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris --- kernel/audit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/audit.c b/kernel/audit.c index 854f4829e654..b8fa4bf8563b 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1216,7 +1216,7 @@ static unsigned long wait_for_auditd(unsigned long sleep_time) unsigned long timeout = sleep_time; DECLARE_WAITQUEUE(wait, current); set_current_state(TASK_UNINTERRUPTIBLE); - add_wait_queue(&audit_backlog_wait, &wait); + add_wait_queue_exclusive(&audit_backlog_wait, &wait); if (audit_backlog_limit && skb_queue_len(&audit_skb_queue) > audit_backlog_limit) -- 2.34.1