[PATCH 2/3] use ExEnterCriticalRegionAndAcquireResourceExclusive and ExReleaseResourceAndLeaveCriticalRegion

[Shawn Hoffman]

Looking back over this, the enter+acquire of the existing code is
shared here, so replacing with exclusive will change behavior.
For now, please ignore this patch.


On Fri, Apr 24, 2020 at 4:44 PM Shawn Hoffman <godisgovernment at gmail.com> wrote:
>
> Signed-off-by: Shawn Hoffman <godisgovernment at gmail.com>
> ---
>  wintun.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/wintun.c b/wintun.c
> index 90e7930..00ac378 100644
> --- a/wintun.c
> +++ b/wintun.c
> @@ -884,15 +884,13 @@ TunDispatchDeviceControl(DEVICE_OBJECT *DeviceObject, IRP *Irp)
>      switch (Stack->Parameters.DeviceIoControl.IoControlCode)
>      {
>      case TUN_IOCTL_REGISTER_RINGS: {
> -        KeEnterCriticalRegion();
> -        ExAcquireResourceSharedLite(&TunDispatchCtxGuard, TRUE);
> +        ExEnterCriticalRegionAndAcquireResourceExclusive(&TunDispatchCtxGuard);
>  #pragma warning(suppress : 28175)
>          TUN_CTX *Ctx = DeviceObject->Reserved;
>          Status = NDIS_STATUS_ADAPTER_NOT_READY;
>          if (Ctx)
>              Status = TunRegisterBuffers(Ctx, Irp);
> -        ExReleaseResourceLite(&TunDispatchCtxGuard);
> -        KeLeaveCriticalRegion();
> +        ExReleaseResourceAndLeaveCriticalRegion(&TunDispatchCtxGuard);
>          break;
>      }
>      case TUN_IOCTL_FORCE_CLOSE_HANDLES:
> @@ -913,14 +911,12 @@ _Use_decl_annotations_
>  static NTSTATUS
>  TunDispatchClose(DEVICE_OBJECT *DeviceObject, IRP *Irp)
>  {
> -    KeEnterCriticalRegion();
> -    ExAcquireResourceSharedLite(&TunDispatchCtxGuard, TRUE);
> +    ExEnterCriticalRegionAndAcquireResourceExclusive(&TunDispatchCtxGuard);
>  #pragma warning(suppress : 28175)
>      TUN_CTX *Ctx = DeviceObject->Reserved;
>      if (Ctx)
>          TunUnregisterBuffers(Ctx, IoGetCurrentIrpStackLocation(Irp)->FileObject);
> -    ExReleaseResourceLite(&TunDispatchCtxGuard);
> -    KeLeaveCriticalRegion();
> +    ExReleaseResourceAndLeaveCriticalRegion(&TunDispatchCtxGuard);
>      return NdisDispatchClose(DeviceObject, Irp);
>  }
>
> --
> 2.26.2.windows.1
>