[ovs-dev] [PATCH v4] datapath-windows: Incorrect assumption of the IRQL

Sorin Vinturis svinturis at cloudbasesolutions.com
Mon Oct 6 15:19:23 UTC 2014


Acquiring a spin lock raises the IRQL to DISPATCH_LEVEL. But
in many places of the code, while holding a spin lock, there
are useless checks for the current IRQL against DISPATCH_LEVEL.
Also, the dispatch flag is not correctly set when calling
NdisAcquireRWLockXXX() functions, which causes an extra check
of the current IRQL.

Signed-off-by: Sorin Vinturis <svinturis at cloudbasesolutions.com>
Reported-by: Sorin Vinturis <svinturis at cloudbasesolutions.com>
Reported-at: https://github.com/openvswitch/ovs-issues/issues/47
Acked-by: Nithin Raju <nithin at vmware.com>
Acked-by: Alin Gabriel Serdean <aserdean at cloudbasesolutions.com>
Acked-by: Eitan Eliahu <eliahue at vmware.com>
---
 datapath-windows/ovsext/Datapath.c |  5 +++--
 datapath-windows/ovsext/Flow.c     | 12 ++++++++----
 datapath-windows/ovsext/PacketIO.c |  2 +-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/datapath-windows/ovsext/Datapath.c b/datapath-windows/ovsext/Datapath.c
index 44cdfc9..8ab689a 100644
--- a/datapath-windows/ovsext/Datapath.c
+++ b/datapath-windows/ovsext/Datapath.c
@@ -1397,8 +1397,9 @@ OvsGetVportDumpNext(POVS_USER_PARAMS_CONTEXT usrParamsCtx,
      * it means we have an array of pids, instead of a single pid.
      * ATM we assume we have one pid only.
     */
-
-    NdisAcquireRWLockRead(gOvsSwitchContext->dispatchLock, &lockState, 0);
+    ASSERT(KeGetCurrentIrql() == DISPATCH_LEVEL);
+    NdisAcquireRWLockRead(gOvsSwitchContext->dispatchLock, &lockState,
+        NDIS_RWL_AT_DISPATCH_LEVEL);
 
     if (gOvsSwitchContext->numVports > 0) {
         /* inBucket: the bucket, used for lookup */
diff --git a/datapath-windows/ovsext/Flow.c b/datapath-windows/ovsext/Flow.c
index 5cab6e1..0648155 100644
--- a/datapath-windows/ovsext/Flow.c
+++ b/datapath-windows/ovsext/Flow.c
@@ -1150,7 +1150,8 @@ OvsDoDumpFlows(OvsFlowDumpInput *dumpInput,
 
     datapath = &gOvsSwitchContext->datapath;
     ASSERT(datapath);
-    OvsAcquireDatapathRead(datapath, &dpLockState, FALSE);
+    ASSERT(KeGetCurrentIrql() == DISPATCH_LEVEL);
+    OvsAcquireDatapathRead(datapath, &dpLockState, TRUE);
 
     head = &datapath->flowTable[rowIndex];
     node = head->Flink;
@@ -1297,7 +1298,8 @@ OvsPutFlowIoctl(PVOID inputBuffer,
 
     datapath = &gOvsSwitchContext->datapath;
     ASSERT(datapath);
-    OvsAcquireDatapathWrite(datapath, &dpLockState, FALSE);
+    ASSERT(KeGetCurrentIrql() == DISPATCH_LEVEL);
+    OvsAcquireDatapathWrite(datapath, &dpLockState, TRUE);
     status = HandleFlowPut(put, datapath, stats);
     OvsReleaseDatapath(datapath, &dpLockState);
 
@@ -1489,7 +1491,8 @@ OvsGetFlowIoctl(PVOID inputBuffer,
 
     datapath = &gOvsSwitchContext->datapath;
     ASSERT(datapath);
-    OvsAcquireDatapathRead(datapath, &dpLockState, FALSE);
+    ASSERT(KeGetCurrentIrql() == DISPATCH_LEVEL);
+    OvsAcquireDatapathRead(datapath, &dpLockState, TRUE);
     flow = OvsLookupFlow(datapath, &getInput->key, &hash, FALSE);
     if (!flow) {
         status = STATUS_INVALID_PARAMETER;
@@ -1524,7 +1527,8 @@ OvsFlushFlowIoctl(UINT32 dpNo)
 
     datapath = &gOvsSwitchContext->datapath;
     ASSERT(datapath);
-    OvsAcquireDatapathWrite(datapath, &dpLockState, FALSE);
+    ASSERT(KeGetCurrentIrql() == DISPATCH_LEVEL);
+    OvsAcquireDatapathWrite(datapath, &dpLockState, TRUE);
     DeleteAllFlows(datapath);
     OvsReleaseDatapath(datapath, &dpLockState);
 
diff --git a/datapath-windows/ovsext/PacketIO.c b/datapath-windows/ovsext/PacketIO.c
index ac7862d..87d7037 100644
--- a/datapath-windows/ovsext/PacketIO.c
+++ b/datapath-windows/ovsext/PacketIO.c
@@ -268,7 +268,7 @@ OvsStartNBLIngress(POVS_SWITCH_CONTEXT switchContext,
             }
 
             ASSERT(KeGetCurrentIrql() == DISPATCH_LEVEL);
-            OvsAcquireDatapathRead(datapath, &dpLockState, dispatch);
+            OvsAcquireDatapathRead(datapath, &dpLockState, TRUE);
 
             flow = OvsLookupFlow(datapath, &key, &hash, FALSE);
             if (flow) {
-- 
1.9.0.msysgit.0



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