From 4b706372f18de53970e4c6887a96459590fef80a Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Tue, 20 Jul 2010 04:52:09 +0000 Subject: drop_monitor: Add error code to detect duplicate state changes Patch to add -EAGAIN error to dropwatch netlink message handling code. -EAGAIN will be returned anytime userspace attempts to transition the state of the drop monitor service to a state that its already in. That allows user space to detect this condition, so it doesn't wait for a success ACK that will never arrive. Tested successfully by me Signed-off-by: Neil Horman Signed-off-by: David S. Miller --- net/core/drop_monitor.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index ad41529fb60f..646ef3bc7200 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -223,6 +223,11 @@ static int set_all_monitor_traces(int state) spin_lock(&trace_state_lock); + if (state == trace_state) { + rc = -EAGAIN; + goto out_unlock; + } + switch (state) { case TRACE_ON: rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); @@ -251,11 +256,12 @@ static int set_all_monitor_traces(int state) if (!rc) trace_state = state; + else + rc = -EINPROGRESS; +out_unlock: spin_unlock(&trace_state_lock); - if (rc) - return -EINPROGRESS; return rc; } -- cgit v1.2.3