datapath-windows: Implement locking in conntrack NAT.

This patch primarily replaces existing ndis RWlock based implementaion
for NAT in conntrack with a spinlock based implementation inside NAT,
module along with some conntrack optimization.

- The 'ovsNatTable' and 'ovsUnNatTable' tables are shared
  between cleanup threads and packet processing thread.
  In order to protect these two tables use a spinlock.
  Also introduce counters to track number of nat entries.
- Introduce a new function OvsGetTcpHeader() to retrieve TCP header
  and payload length, to optimize for TCP traffic.
- Optimize conntrack look up.
- Remove 'bucketlockRef' member from conntrack entry structure.

Testing:
Verified loading/unloading the driver with driver verified enabled.
Ran TCP/UDP and ICMP traffic.

Signed-off-by: Anand Kumar <kumaranand@vmware.com>
Acked-by: Alin Gabriel Serdean <aserdean@ovn.org>
Signed-off-by: Alin Gabriel Serdean <aserdean@ovn.org>

1 files changed, 27 insertions, 1 deletions

diff --git a/datapath-windows/ovsext/Conntrack-nat.c b/datapath-windows/ovsext/Conntrack-nat.c
index da1814f96..1607d4c4f 100644
--- a/datapath-windows/ovsext/Conntrack-nat.c
+++ b/datapath-windows/ovsext/Conntrack-nat.c
@@ -3,7 +3,8 @@
 
 PLIST_ENTRY ovsNatTable = NULL;
 PLIST_ENTRY ovsUnNatTable = NULL;
-
+static NDIS_SPIN_LOCK ovsCtNatLock;
+static ULONG ovsNatEntries;
 /*
  *---------------------------------------------------------------------------
  * OvsHashNatKey
@@ -109,6 +110,8 @@ NTSTATUS OvsNatInit()
         InitializeListHead(&ovsUnNatTable[i]);
     }
 
+    NdisAllocateSpinLock(&ovsCtNatLock);
+    ovsNatEntries = 0;
     return STATUS_SUCCESS;
 }
 
@@ -121,6 +124,11 @@ NTSTATUS OvsNatInit()
 VOID OvsNatFlush(UINT16 zone)
 {
     PLIST_ENTRY link, next;
+    if (!ovsNatEntries) {
+        return;
+    }
+
+    NdisAcquireSpinLock(&ovsCtNatLock);
     for (int i = 0; i < NAT_HASH_TABLE_SIZE; i++) {
         LIST_FORALL_SAFE(&ovsNatTable[i], link, next) {
             POVS_NAT_ENTRY entry =
@@ -131,6 +139,7 @@ VOID OvsNatFlush(UINT16 zone)
             }
         }
     }
+    NdisReleaseSpinLock(&ovsCtNatLock);
 }
 
 /*
@@ -142,12 +151,17 @@ VOID OvsNatFlush(UINT16 zone)
 VOID OvsNatCleanup()
 {
     if (ovsNatTable == NULL) {
+       NdisFreeSpinLock(&ovsCtNatLock);
        return;
     }
+
+    NdisAcquireSpinLock(&ovsCtNatLock);
     OvsFreeMemoryWithTag(ovsNatTable, OVS_CT_POOL_TAG);
     OvsFreeMemoryWithTag(ovsUnNatTable, OVS_CT_POOL_TAG);
     ovsNatTable = NULL;
     ovsUnNatTable = NULL;
+    NdisReleaseSpinLock(&ovsCtNatLock);
+    NdisFreeSpinLock(&ovsCtNatLock);
 }
 
 /*
@@ -250,10 +264,13 @@ static UINT32 OvsNatHashRange(const OVS_CT_ENTRY *entry, UINT32 basis)
 VOID
 OvsNatAddEntry(OVS_NAT_ENTRY* entry)
 {
+    NdisAcquireSpinLock(&ovsCtNatLock);
     InsertHeadList(OvsNatGetBucket(&entry->key, FALSE),
                    &entry->link);
     InsertHeadList(OvsNatGetBucket(&entry->value, TRUE),
                    &entry->reverseLink);
+    NdisReleaseSpinLock(&ovsCtNatLock);
+    NdisInterlockedIncrement((PLONG)&ovsNatEntries);
 }
 
 /*
@@ -399,21 +416,29 @@ OvsNatLookup(const OVS_CT_KEY *ctKey, BOOLEAN reverse)
     PLIST_ENTRY link;
     POVS_NAT_ENTRY entry;
 
+    if (!ovsNatEntries) {
+        return NULL;
+    }
+
+    NdisAcquireSpinLock(&ovsCtNatLock);
     LIST_FORALL(OvsNatGetBucket(ctKey, reverse), link) {
         if (reverse) {
             entry = CONTAINING_RECORD(link, OVS_NAT_ENTRY, reverseLink);
 
             if (OvsNatKeyAreSame(ctKey, &entry->value)) {
+                NdisReleaseSpinLock(&ovsCtNatLock);
                 return entry;
             }
         } else {
             entry = CONTAINING_RECORD(link, OVS_NAT_ENTRY, link);
 
             if (OvsNatKeyAreSame(ctKey, &entry->key)) {
+                NdisReleaseSpinLock(&ovsCtNatLock);
                 return entry;
             }
         }
     }
+    NdisReleaseSpinLock(&ovsCtNatLock);
     return NULL;
 }
 
@@ -432,6 +457,7 @@ OvsNatDeleteEntry(POVS_NAT_ENTRY entry)
     RemoveEntryList(&entry->link);
     RemoveEntryList(&entry->reverseLink);
     OvsFreeMemoryWithTag(entry, OVS_CT_POOL_TAG);
+    NdisInterlockedDecrement((PLONG)&ovsNatEntries);
 }
 
 /*