[PATCH 5/8] audit: efficiency fix 2: request exclusive wait since all need same resource
Richard Guy Briggs
rgb at redhat.com
Wed Sep 18 19:06:50 UTC 2013
author: Dan Duval <dan.duval at oracle.com>
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 <dan.duval at oracle.com>
Signed-off-by: Chuck Anderson <chuck.anderson at oracle.com>
Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
---
kernel/audit.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/audit.c b/kernel/audit.c
index 25fab2d..990d02f 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1061,7 +1061,7 @@ 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)
--
1.7.1
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