Author: gedmurphy
Date: Fri May 19 09:15:35 2017
New Revision: 74588
URL: http://svn.reactos.org/svn/reactos?rev=74588&view=rev
Log:
[FLTMGR}
- Implement FltAcquirePushLockExclusive, FltAcquirePushLockShared and
FltReleasePushLock. Lifted from ntos' internal pushlock routines.
- Implement FltpObjectPointerReference and partially implement
FltpObjectPointerDerference
Modified:
trunk/reactos/drivers/filters/fltmgr/Object.c
Modified: trunk/reactos/drivers/filters/fltmgr/Object.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filters/fltmgr/Object.c?rev=74588&r1=74587&r2=74588&view=diff
==============================================================================
--- trunk/reactos/drivers/filters/fltmgr/Object.c [iso-8859-1] (original)
+++ trunk/reactos/drivers/filters/fltmgr/Object.c [iso-8859-1] Fri May 19
09:15:35 2017
@@ -20,7 +20,18 @@
/* DATA *********************************************************************/
-
+#define ExpChangePushlock(x, y, z)
InterlockedCompareExchangePointer((PVOID*)x, (PVOID)y, (PVOID)z)
+
+//
+// Pushlock bits
+//
+#define EX_PUSH_LOCK_LOCK_V ((ULONG_PTR)0x0)
+#define EX_PUSH_LOCK_LOCK ((ULONG_PTR)0x1)
+#define EX_PUSH_LOCK_WAITING ((ULONG_PTR)0x2)
+#define EX_PUSH_LOCK_WAKING ((ULONG_PTR)0x4)
+#define EX_PUSH_LOCK_MULTIPLE_SHARED ((ULONG_PTR)0x8)
+#define EX_PUSH_LOCK_SHARE_INC ((ULONG_PTR)0x10)
+#define EX_PUSH_LOCK_PTR_BITS ((ULONG_PTR)0xf)
/* EXPORTED FUNCTIONS ******************************************************/
@@ -42,6 +53,85 @@
FltObjectDereference(_Inout_ PVOID Object)
{
FltpExReleaseRundownProtection(&((PFLT_OBJECT)Object)->RundownRef);
+}
+
+
+_Acquires_lock_(_Global_critical_region_)
+_IRQL_requires_max_(APC_LEVEL)
+VOID
+FLTAPI
+FltAcquirePushLockExclusive(_Inout_ _Requires_lock_not_held_(*_Curr_)
_Acquires_lock_(*_Curr_) PEX_PUSH_LOCK PushLock)
+{
+ KeEnterCriticalRegion();
+
+ /* Try acquiring the lock */
+ if (InterlockedBitTestAndSet((PLONG)PushLock, EX_PUSH_LOCK_LOCK_V))
+ {
+ /* Someone changed it, use the slow path */
+ ExfAcquirePushLockExclusive(PushLock);
+ }
+
+ /* Sanity check */
+ FLT_ASSERT(PushLock->Locked);
+}
+
+
+_Acquires_lock_(_Global_critical_region_)
+_IRQL_requires_max_(APC_LEVEL)
+VOID
+FLTAPI
+FltAcquirePushLockShared(_Inout_ _Requires_lock_not_held_(*_Curr_)
_Acquires_lock_(*_Curr_) PEX_PUSH_LOCK PushLock)
+{
+ EX_PUSH_LOCK NewValue;
+
+ KeEnterCriticalRegion();
+
+ /* Try acquiring the lock */
+ NewValue.Value = EX_PUSH_LOCK_LOCK | EX_PUSH_LOCK_SHARE_INC;
+ if (ExpChangePushlock(PushLock, NewValue.Ptr, 0))
+ {
+ /* Someone changed it, use the slow path */
+ ExfAcquirePushLockShared(PushLock);
+ }
+
+ /* Sanity checks */
+ ASSERT(PushLock->Locked);
+}
+
+_Releases_lock_(_Global_critical_region_)
+_IRQL_requires_max_(APC_LEVEL)
+VOID
+FLTAPI
+FltReleasePushLock(_Inout_ _Requires_lock_held_(*_Curr_)
_Releases_lock_(*_Curr_) PEX_PUSH_LOCK PushLock)
+{
+ EX_PUSH_LOCK OldValue = *PushLock;
+ EX_PUSH_LOCK NewValue;
+
+ /* Sanity checks */
+ FLT_ASSERT(OldValue.Locked);
+
+ /* Check if the pushlock is shared */
+ if (OldValue.Shared > 1)
+ {
+ /* Decrease the share count */
+ NewValue.Value = OldValue.Value - EX_PUSH_LOCK_SHARE_INC;
+ }
+ else
+ {
+ /* Clear the pushlock entirely */
+ NewValue.Value = 0;
+ }
+
+ /* Check if nobody is waiting on us and try clearing the lock here */
+ if ((OldValue.Waiting) ||
+ (ExpChangePushlock(PushLock, NewValue.Ptr, OldValue.Ptr) !=
+ OldValue.Ptr))
+ {
+ /* We have waiters, use the long path */
+ ExfReleasePushLock(PushLock);
+ }
+
+ KeLeaveCriticalRegion();
}
@@ -157,3 +247,26 @@
return Status;
}
+
+ULONG
+FltpObjectPointerReference(_In_ PFLT_OBJECT Object)
+{
+ PULONG Result;
+
+ /* Store the old count and increment */
+ Result = &Object->PointerCount;
+ InterlockedIncrement((PLONG)&Object->PointerCount);
+
+ /* Return the initial value */
+ return *Result;
+}
+
+VOID
+FltpObjectPointerDereference(_In_ PFLT_OBJECT Object)
+{
+ if (!InterlockedDecrement((PLONG)Object->PointerCount))
+ {
+ // Cleanup
+ FLT_ASSERT(FALSE);
+ }
+}
