From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: [PATCH] drop_monitor: Add error code to detect duplicate state changes Date: Tue, 20 Jul 2010 10:52:09 -0400 Message-ID: <20100720145209.GE1995@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, nhorman@tuxdriver.com To: netdev@vger.kernel.org Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:60043 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758499Ab0GTOyh (ORCPT ); Tue, 20 Jul 2010 10:54:37 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Hey- 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 drop_monitor.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index ad41529..646ef3b 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; }