Changeset 71987 in vbox for trunk

Timestamp:

Apr 23, 2018 4:54:18 PM (7 years ago)

Author:

vboxsync

Message:

Serial/DrvChar: Use critical section to protect send path against sending stale data under certain circumstances

File:

• trunk/src/VBox/Devices/Serial/DrvChar.cpp (modified) (8 diffs)

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

@@ -32 +32 @@
 #include <iprt/poll.h>
 #include <iprt/stream.h>
+#include <iprt/critsect.h>
 #include <iprt/semaphore.h>
 #include <iprt/uuid.h>
@@ -73 +74 @@
     /** Event semaphore for the read relay thread. */
     RTSEMEVENT                  hEvtSemRead;
+    /** Critical section protection the send part. */
+    RTCRITSECT                  CritSectSend;
 
     /** Internal send FIFO queue */
@@ -120 +123 @@
     PDRVCHAR pThis = RT_FROM_MEMBER(pInterface, DRVCHAR, ICharConnector);
     const char *pbBuffer = (const char *)pvBuf;
+    int rc = VINF_SUCCESS;
 
     LogFlow(("%s: pvBuf=%#p cbWrite=%d\n", __FUNCTION__, pvBuf, cbWrite));
 
-    for (uint32_t i = 0; i < cbWrite; i++)
+    RTCritSectEnter(&pThis->CritSectSend);
+
+    for (uint32_t i = 0; i < cbWrite && RT_SUCCESS(rc); i++)
     {
-        if (ASMAtomicXchgBool(&pThis->fSending, true))
-            return VERR_BUFFER_OVERFLOW;
-
-        pThis->u8SendByte = pbBuffer[i];
-        pThis->pDrvStream->pfnPollInterrupt(pThis->pDrvStream);
-        STAM_COUNTER_INC(&pThis->StatBytesWritten);
+        if (!ASMAtomicXchgBool(&pThis->fSending, true))
+        {
+            pThis->u8SendByte = pbBuffer[i];
+            pThis->pDrvStream->pfnPollInterrupt(pThis->pDrvStream);
+            STAM_COUNTER_INC(&pThis->StatBytesWritten);
+        }
+        else
+            rc = VERR_BUFFER_OVERFLOW;
     }
-    return VINF_SUCCESS;
+
+    RTCritSectLeave(&pThis->CritSectSend);
+    return rc;
 }
 
@@ -182 +192 @@
             if (fEvtsRecv & RTPOLL_EVT_WRITE)
             {
+                RTCritSectEnter(&pThis->CritSectSend);
                 Assert(pThis->fSending);
 
@@ -206 +217 @@
                     break;
                 }
+                RTCritSectLeave(&pThis->CritSectSend);
             }
 
@@ -358 +370 @@
     PDMDRV_CHECK_VERSIONS_RETURN_VOID(pDrvIns);
 
+    if (RTCritSectIsInitialized(&pThis->CritSectSend))
+        RTCritSectDelete(&pThis->CritSectSend);
+
     if (pThis->hEvtSemRead != NIL_RTSEMEVENT)
     {
@@ -393 +408 @@
     pThis->ICharConnector.pfnSetBreak       = drvCharSetBreak;
 
+    int rc = RTCritSectInit(&pThis->CritSectSend);
+    if (RT_FAILURE(rc))
+        return PDMDrvHlpVMSetError(pDrvIns, rc, RT_SRC_POS,
+                                   N_("Char#%d: Failed to create critical section"), pDrvIns->iInstance);
+
     /*
      * Get the ICharPort interface of the above driver/device.
@@ -404 +424 @@
      */
     PPDMIBASE pBase;
-    int rc = PDMDrvHlpAttach(pDrvIns, fFlags, &pBase);
+    rc = PDMDrvHlpAttach(pDrvIns, fFlags, &pBase);
     if (RT_FAILURE(rc))
         return rc; /* Don't call PDMDrvHlpVMSetError here as we assume that the driver already set an appropriate error */