[ovs-dev] [PATCH v2] datapath-windows: Add an upper limit to conntrack entries

[Sairam Venugopal]

The current implementation lacked an upper bound of number of entries in
the system. Set the size to ~2M (2^21) for the time being.

Signed-off-by: Sairam Venugopal <vsairam at vmware.com>
---
 datapath-windows/ovsext/Conntrack.c | 10 ++++++++++
 datapath-windows/ovsext/Conntrack.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/datapath-windows/ovsext/Conntrack.c b/datapath-windows/ovsext/Conntrack.c
index ce8c1c8..8bcda05 100644
--- a/datapath-windows/ovsext/Conntrack.c
+++ b/datapath-windows/ovsext/Conntrack.c
@@ -722,6 +722,16 @@ OvsCtExecute_(OvsForwardingContext *fwdCtx,
         entry = NULL;
     }
 
+    if (!entry && commit && ctTotalEntries >= CT_MAX_ENTRIES) {
+        /* Don't proceed with processing if the max limit has been hit.
+         * This blocks only new entries from being created and doesn't
+         * affect existing connections.
+         */
+        NdisReleaseRWLock(ovsConntrackLockObj, &lockState);
+        OVS_LOG_ERROR("Conntrack Limit hit: %lu", ctTotalEntries);
+        return NDIS_STATUS_RESOURCES;
+    }
+
     if (!entry) {
         /* If no matching entry was found, create one and add New state */
         entry = OvsCtEntryCreate(fwdCtx, key->ipKey.nwProto,
diff --git a/datapath-windows/ovsext/Conntrack.h b/datapath-windows/ovsext/Conntrack.h
index bca7d90..be5f34d 100644
--- a/datapath-windows/ovsext/Conntrack.h
+++ b/datapath-windows/ovsext/Conntrack.h
@@ -131,6 +131,7 @@ typedef struct OvsConntrackKeyLookupCtx {
     BOOLEAN         related;
 } OvsConntrackKeyLookupCtx;
 
+#define CT_MAX_ENTRIES 1 << 21
 #define CT_HASH_TABLE_SIZE ((UINT32)1 << 10)
 #define CT_HASH_TABLE_MASK (CT_HASH_TABLE_SIZE - 1)
 #define CT_INTERVAL_SEC 10000000LL //1s
-- 
2.9.0.windows.1