Changeset 73618 in vbox for trunk/src/VBox

Timestamp:

Aug 10, 2018 2:16:56 PM (6 years ago)

Author:

vboxsync

Message:

Devices/Serial/DrvTCP: Fixed stalling reads on Windows hosts caused by slightly different behavior of RTPoll() there, also don't let the guest starve if there is data to read by exiting to early if the transmit buffer isn't full

File:

• trunk/src/VBox/Devices/Serial/DrvTCP.cpp (modified) (3 diffs)

trunk/src/VBox/Devices/Serial/DrvTCP.cpp

@@ -133 +133 @@
         else
         {
+            /* Always include error event. */
+            fEvts |= RTPOLL_EVT_ERROR;
+            rc = RTPollSetEventsChange(pThis->hPollSet, DRVTCP_POLLSET_ID_SOCKET, fEvts);
+            AssertRC(rc);
+        }
+    }
+
+    if (RT_SUCCESS(rc))
+    {
+        while (RT_SUCCESS(rc))
+        {
+            uint32_t fEvtsRecv = 0;
+            uint32_t idHnd = 0;
+
             /*
-             * Just return if the send buffer wasn't full till now and
-             * the caller wants to check whether writing is possible with
-             * the event set.
+             * Just check for data available to be read if the send buffer wasn't full till now and
+             * the caller wants to check whether writing is possible with the event set.
              *
              * On Windows the write event is only posted after a send operation returned
@@ -143 +156 @@
              */
             if (   (fEvts & RTPOLL_EVT_WRITE)
-                && !pThis->fXmitBufFull)
-            {
-                *pfEvts = RTPOLL_EVT_WRITE;
-                return VINF_SUCCESS;
-            }
-
-            /* Always include error event. */
-            fEvts |= RTPOLL_EVT_ERROR;
-            rc = RTPollSetEventsChange(pThis->hPollSet, DRVTCP_POLLSET_ID_SOCKET, fEvts);
-            AssertRC(rc);
-        }
-    }
-
-    if (RT_SUCCESS(rc))
-    {
-        while (RT_SUCCESS(rc))
-        {
-            uint32_t fEvtsRecv = 0;
-            uint32_t idHnd = 0;
+                && !pThis->fXmitBufFull
+                && pThis->fTcpSockInPollSet)
+                cMillies = 0;
 
             rc = RTPoll(pThis->hPollSet, cMillies, &fEvtsRecv, &idHnd);
@@ -209 +206 @@
                         if (fEvtsRecv & RTPOLL_EVT_WRITE)
                             pThis->fXmitBufFull = false;
+                        else if (!pThis->fXmitBufFull)
+                            fEvtsRecv |= RTPOLL_EVT_WRITE;
                         *pfEvts = fEvtsRecv;
                         break;
                     }
                 }
+            }
+            else if (   rc == VERR_TIMEOUT
+                     && !pThis->fXmitBufFull)
+            {
+                *pfEvts = RTPOLL_EVT_WRITE;
+                rc = VINF_SUCCESS;
+                break;
             }
         }