[RFC PATCH 4/9] granter: Split GranterTryPut to its own function

[Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>]

This allows ring consumers to test for still-pending grants and
eventually defer grant revocation.

Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
---
 src/xenvbd/granter.c | 37 +++++++++++++++++++++++++++++--------
 src/xenvbd/granter.h |  7 +++++++
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/src/xenvbd/granter.c b/src/xenvbd/granter.c
index 0673891..74a786d 100644
--- a/src/xenvbd/granter.c
+++ b/src/xenvbd/granter.c
@@ -346,31 +346,52 @@ fail1:
     return status;
 }
 
+_Check_return_
+NTSTATUS
+GranterTryPut(
+    _Inout_ PXENVBD_GRANTER Granter,
+    _In_ PVOID              Handle
+    )
+{
+    PXENBUS_GNTTAB_ENTRY    Entry = Handle;
+    NTSTATUS                status;
+
+    ASSERT3P(Granter->Cache, !=, NULL);
+
+    status = XENBUS_GNTTAB(RevokeForeignAccess,
+                           &Granter->GnttabInterface,
+                           Granter->Cache,
+                           FALSE,
+                           Entry);
+    if (!NT_SUCCESS(status))
+        goto fail1;
+
+    InterlockedDecrement(&Granter->Current);
+
+    return STATUS_SUCCESS;
+
+fail1:
+    return status;
+}
+
 VOID
 GranterPut(
     _Inout_ PXENVBD_GRANTER Granter,
     _In_ PVOID              Handle
     )
 {
-    PXENBUS_GNTTAB_ENTRY    Entry = Handle;
     NTSTATUS                status;
 
     if (Granter->Connected == FALSE)
         return;
 
     for (;;) {
-        status = XENBUS_GNTTAB(RevokeForeignAccess,
-                               &Granter->GnttabInterface,
-                               Granter->Cache,
-                               FALSE,
-                               Entry);
+        status = GranterTryPut(Granter, Handle);
         if (NT_SUCCESS(status))
             break;
 
         YieldProcessor();
     }
-
-    InterlockedDecrement(&Granter->Current);
 }
 
 ULONG
diff --git a/src/xenvbd/granter.h b/src/xenvbd/granter.h
index e8d0899..e609a8a 100644
--- a/src/xenvbd/granter.h
+++ b/src/xenvbd/granter.h
@@ -84,6 +84,13 @@ GranterGet(
     _Outptr_ PVOID          *Handle
     );
 
+_Check_return_
+extern NTSTATUS
+GranterTryPut(
+    _Inout_ PXENVBD_GRANTER Granter,
+    _In_ PVOID              Handle
+    );
+
 extern VOID
 GranterPut(
     _Inout_ PXENVBD_GRANTER Granter,
-- 
2.56.0.windows.3



--
Ngoc Tu Dinh | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech