Changeset 25524 in vbox for trunk/src/VBox/Runtime/r3

Timestamp:

Dec 20, 2009 4:56:30 PM (15 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

56197

Message:

semrw-posix.cpp,tstRTSemRW: added an insufficient workaround for the glibc pthread_rwlock_unlock issue.

File:

• trunk/src/VBox/Runtime/r3/posix/semrw-posix.cpp (modified) (6 diffs)

trunk/src/VBox/Runtime/r3/posix/semrw-posix.cpp

@@ -73 +73 @@
     /** The usual magic. (RTSEMRW_MAGIC) */
     uint32_t            u32Magic;
-    /* Alignment padding. */
-    uint32_t            u32Padding;
+    /** The number of readers.
+     * (For preventing screwing up the lock on linux). */
+    uint32_t volatile   cReaders;
     /** Number of write recursions. */
     uint32_t            cWrites;
@@ -112 +113 @@
             if (!rc)
             {
-                pThis->u32Magic = RTSEMRW_MAGIC;
-                pThis->u32Padding = 0;
-                pThis->cWrites = 0;
+                pThis->u32Magic     = RTSEMRW_MAGIC;
+                pThis->cReaders     = 0;
+                pThis->cWrites      = 0;
                 pThis->cWriterReads = 0;
-                pThis->Writer = (pthread_t)-1;
+                pThis->Writer       = (pthread_t)-1;
 #ifdef RTSEMRW_STRICT
                 RTLockValidatorRecInit(&pThis->ValidatorWrite, NIL_RTLOCKVALIDATORCLASS, RTLOCKVALIDATOR_SUB_CLASS_NONE, NULL, pThis);
@@ -149 +150 @@
                     VERR_INVALID_HANDLE);
     Assert(pThis->Writer == (pthread_t)-1);
+    Assert(!pThis->cReaders);
     Assert(!pThis->cWrites);
     Assert(!pThis->cWriterReads);
@@ -272 +274 @@
     }
 
+    ASMAtomicIncU32(&pThis->cReaders);
 #ifdef RTSEMRW_STRICT
     RTLockValidatorAddReadOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
@@ -323 +326 @@
         return rc9;
 #endif
+#ifdef RT_OS_LINUX /* glibc (at least 2.8) may screw up when unlocking a lock we don't own. */
+    if (ASMAtomicReadU32(&pThis->cReaders) == 0)
+    {
+        AssertMsgFailed(("Not owner of %p\n", pThis));
+        return VERR_NOT_OWNER;
+    }
+#endif
+    ASMAtomicDecU32(&pThis->cReaders);
     int rc = pthread_rwlock_unlock(&pThis->RWLock);
     if (rc)
     {
+        ASMAtomicIncU32(&pThis->cReaders);
         AssertMsgFailed(("Failed read unlock read-write sem %p, rc=%d.\n", RWSem, rc));
         return RTErrConvertFromErrno(rc);
@@ -426 +438 @@
     ATOMIC_SET_PTHREAD_T(&pThis->Writer, Self);
     pThis->cWrites = 1;
+    Assert(!pThis->cReaders);
 #ifdef RTSEMRW_STRICT
     RTLockValidatorSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos);