[ros-dev] RE: [ros-diffs] [navaraf] 17511: Implement the most over-optimized lockin NT - the NDIS_RW_LOCK.

[Casper Hornstrup]

Some constants for the magic numbers would be nice.

________________________________________
From: [e-mail] [mailto:[e-mail]] On Behalf Of [e-mail]
Sent: 24. august 2005 14:21
To: [e-mail]
Subject: [ros-diffs] [navaraf] 17511: Implement the most over-optimized lockin NT - the NDIS_RW_LOCK.

Implement the most over-optimized lock in NT - the NDIS_RW_LOCK.
Modified: trunk/reactos/drivers/net/ndis/ndis/control.c
Modified: trunk/reactos/drivers/net/ndis/ndis/main.c
Modified: trunk/reactos/drivers/net/ndis/ndis/stubs.c

+/*
+ * @implemented
+ */
+VOID
+EXPORT
 NdisAcquireReadWriteLock(
     IN  PNDIS_RW_LOCK   Lock,
     IN  BOOLEAN         fWrite,
@@ -29,13 +48,88 @@
  *    NDIS 5.0
  */
 {
-    UNIMPLEMENTED
+  ULONG RefCount;
+  UCHAR ProcessorNumber;
+  UCHAR BusyLoop;
+
+  ASSERT_IRQL(DISPATCH_LEVEL);
+
+  if (fWrite) {
+    if (Lock->Context == PsGetCurrentThread()) {
+      LockState->LockState = 2;
+    } else {
+      KeAcquireSpinLock(&Lock->SpinLock, &LockState->OldIrql);
+      /* Check if any other processor helds a shared lock. */
+      for (ProcessorNumber = KeNumberProcessors; ProcessorNumber--; ) {
+        if (ProcessorNumber != KeGetCurrentProcessorNumber()) {
+          /* Wait till the shared lock is released. */
+          while (Lock->RefCount[ProcessorNumber].RefCount != 0) {
+            for (BusyLoop = 32; BusyLoop--; )
+              ;
+          }
+        }
+      }
+      Lock->Context = PsGetCurrentThread();
+      LockState->LockState = 4;
+    }
+  } else {
+    KeRaiseIrql(DISPATCH_LEVEL, &LockState->OldIrql);
+    RefCount = InterlockedIncrement((PLONG)&Lock->RefCount[KeGetCurrentProcessorNumber()].RefCount);
+    /* Racing with a exclusive write lock case. */
+    if (Lock->SpinLock != 0) {
+      if (RefCount == 1) {
+        if (Lock->Context != PsGetCurrentThread()) {
+          /* Wait for the exclusive lock to be released. */
+          Lock->RefCount[KeGetCurrentProcessorNumber()].RefCount--;
+          KefAcquireSpinLockAtDpcLevel(&Lock->SpinLock);
+          Lock->RefCount[KeGetCurrentProcessorNumber()].RefCount++;
+          KefReleaseSpinLockFromDpcLevel(&Lock->SpinLock);
+        }
+      }
+    }
+    LockState->LockState = 3;
+  }
 }

/*
  * @implemented
  */
+VOID
+EXPORT
+NdisReleaseReadWriteLock(
+    IN  PNDIS_RW_LOCK   Lock,
+    IN  PLOCK_STATE     LockState)
+/*
+ * FUNCTION:
+ * ARGUMENTS:
+ * NOTES:
+ *    NDIS 5.0
+ */
+{
+  switch (LockState->LockState) {
+    case 2: /* Exclusive write lock, recursive */
+      return;
+
+    case 3: /* Shared read lock */
+      Lock->RefCount[KeGetCurrentProcessorNumber()].RefCount--;
+      LockState->LockState = -1;
+      if (LockState->OldIrql < DISPATCH_LEVEL)
+        KeLowerIrql(LockState->OldIrql);
+      return;
+
+    case 4: /* Exclusive write lock */
+      Lock->Context = NULL;
+      LockState->LockState = -1;
+      KfReleaseSpinLock(&Lock->SpinLock, LockState->OldIrql);
+      return;
+  }  
+}
+
+