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authorNeil Horman <nhorman@tuxdriver.com>2010-07-20 04:52:09 +0000
committerDavid S. Miller <davem@davemloft.net>2010-07-20 13:28:04 -0700
commit4b706372f18de53970e4c6887a96459590fef80a (patch)
tree545fe784620c3dc9f0fd8a6efdeb2cbe566779c9
parentd79d991379af35d43f003f162e8650e72965b8ca (diff)
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 <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/drop_monitor.c10
1 files changed, 8 insertions, 2 deletions
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;
}