Changeset 37419 in vbox

Timestamp:

Jun 11, 2011 8:25:37 PM (14 years ago)

Author:

vboxsync

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

72218

Message:

PDM/IPRT CritSect: Introduced the NOP critical section for simplifying locking in IOM and TM. (Revisiting device emulation locking, making it more fine grained over time.)

Location:

trunk

Files:

• include/iprt/critsect.h (modified) (1 diff)
• src/VBox/Runtime/generic/critsect-generic.cpp (modified) (6 diffs)
• src/VBox/VMM/VMMAll/PDMAllCritSect.cpp (modified) (3 diffs)
• src/VBox/VMM/VMMR3/PDMCritSect.cpp (modified) (3 diffs)

trunk/include/iprt/critsect.h

@@ -102 +102 @@
 /** Bootstrap hack for use with certain memory allocator locks only! */
 #define RTCRITSECT_FLAGS_BOOTSTRAP_HACK UINT32_C(0x00000004)
+/** If set, the critical section becomes a dummy that doesn't serialize any
+ * threads.  This flag can only be set at creation time.
+ *
+ * The intended use is avoiding lots of conditional code where some component
+ * might or might not require entering a critical section before access. */
+#define RTCRITSECT_FLAGS_NOP            UINT32_C(0x00000008)
 /** @} */
 

trunk/src/VBox/Runtime/generic/critsect-generic.cpp

@@ -52 +52 @@
                              const char *pszNameFmt, ...)
 {
-    AssertReturn(!(fFlags & ~(RTCRITSECT_FLAGS_NO_NESTING | RTCRITSECT_FLAGS_NO_LOCK_VAL | RTCRITSECT_FLAGS_BOOTSTRAP_HACK)),
+    AssertReturn(!(fFlags & ~(RTCRITSECT_FLAGS_NO_NESTING | RTCRITSECT_FLAGS_NO_LOCK_VAL | RTCRITSECT_FLAGS_BOOTSTRAP_HACK | RTCRITSECT_FLAGS_NOP)),
                  VERR_INVALID_PARAMETER);
 
@@ -66 +66 @@
     int rc = VINF_SUCCESS;
 #ifdef RTCRITSECT_STRICT
-    if (!(fFlags & RTCRITSECT_FLAGS_BOOTSTRAP_HACK))
+    if (!(fFlags & (RTCRITSECT_FLAGS_BOOTSTRAP_HACK | RTCRITSECT_FLAGS_NOP)))
     {
         if (!pszNameFmt)
@@ -111 +111 @@
     AssertPtrReturn(pCritSect, RTLOCKVAL_SUB_CLASS_INVALID);
     AssertReturn(pCritSect->u32Magic == RTCRITSECT_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID);
+    AssertReturn(!(pCritSect->fFlags & RTCRITSECT_FLAGS_NOP), RTLOCKVAL_SUB_CLASS_INVALID);
     return RTLockValidatorRecExclSetSubClass(pCritSect->pValidatorRec, uSubClass);
 #else
@@ -122 +123 @@
     Assert(pCritSect);
     Assert(pCritSect->u32Magic == RTCRITSECT_MAGIC);
-    RTNATIVETHREAD  NativeThreadSelf = RTThreadNativeSelf();
+    /*AssertReturn(pCritSect->u32Magic == RTCRITSECT_MAGIC, VERR_SEM_DESTROYED);*/
+
+    /*
+     * Return straight away if NOP.
+     */
+    if (pCritSect->fFlags & RTCRITSECT_FLAGS_NOP)
+        return VINF_SUCCESS;
 
     /*
      * Try take the lock. (cLockers is -1 if it's free)
      */
+    RTNATIVETHREAD NativeThreadSelf = RTThreadNativeSelf();
     if (!ASMAtomicCmpXchgS32(&pCritSect->cLockers, 0, -1))
     {
@@ -186 +194 @@
 DECL_FORCE_INLINE(int) rtCritSectEnter(PRTCRITSECT pCritSect, PCRTLOCKVALSRCPOS pSrcPos)
 {
-    Assert(pCritSect);
-    Assert(pCritSect->u32Magic == RTCRITSECT_MAGIC);
+    AssertPtr(pCritSect);
+    AssertReturn(pCritSect->u32Magic == RTCRITSECT_MAGIC, VERR_SEM_DESTROYED);
+
+    /*
+     * Return straight away if NOP.
+     */
+    if (pCritSect->fFlags & RTCRITSECT_FLAGS_NOP)
+        return VINF_SUCCESS;
+
+    /*
+     * How is calling and is the order right?
+     */
     RTNATIVETHREAD  NativeThreadSelf = RTThreadNativeSelf();
-
-    /* If the critical section has already been destroyed, then inform the caller. */
-    if (pCritSect->u32Magic != RTCRITSECT_MAGIC)
-        return VERR_SEM_DESTROYED;
-
-#ifdef RTCRITSECT_STRICT
-    RTTHREAD hThreadSelf = pCritSect->pValidatorRec
-                         ? RTThreadSelfAutoAdopt()
-                         : RTThreadSelf();
-    int      rc9;
+#ifdef RTCRITSECT_STRICT
+    RTTHREAD        hThreadSelf = pCritSect->pValidatorRec
+                                ? RTThreadSelfAutoAdopt()
+                                : RTThreadSelf();
+    int             rc9;
     if (pCritSect->pValidatorRec) /* (bootstap) */
     {
@@ -305 +318 @@
 {
     /*
-     * Assert ownership and so on.
+     * Assert sanity and check for NOP.
      */
     Assert(pCritSect);
     Assert(pCritSect->u32Magic == RTCRITSECT_MAGIC);
+    if (pCritSect->fFlags & RTCRITSECT_FLAGS_NOP)
+        return VINF_SUCCESS;
+
+    /*
+     * Assert ownership and so on.
+     */
     Assert(pCritSect->cNestings > 0);
     Assert(pCritSect->cLockers >= 0);

trunk/src/VBox/VMM/VMMAll/PDMAllCritSect.cpp

@@ -195 +195 @@
      * See if we're lucky.
      */
+    /* NOP ... */
+    if (pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP)
+        return VINF_SUCCESS;
+
     RTNATIVETHREAD hNativeSelf = pdmCritSectGetNativeSelf(pCritSect);
-    /* Not owned ... */
+    /* ... not owned ... */
     if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
         return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
@@ -367 +371 @@
      * See if we're lucky.
      */
+    /* NOP ... */
+    if (pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP)
+        return VINF_SUCCESS;
+
     RTNATIVETHREAD hNativeSelf = pdmCritSectGetNativeSelf(pCritSect);
-    /* Not owned ... */
+    /* ... not owned ... */
     if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
         return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
@@ -481 +489 @@
     Assert(pCritSect->s.Core.NativeThreadOwner == pdmCritSectGetNativeSelf(pCritSect));
     Assert(pCritSect->s.Core.cNestings >= 1);
+
+    /*
+     * Check for NOP sections.
+     */
+    if (pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP)
+        return;
 
     /*

trunk/src/VBox/VMM/VMMR3/PDMCritSect.cpp

@@ -123 +123 @@
  * @param   va              Arguments for the format string.
  */
-static int pdmR3CritSectInitOne(PVM pVM, PPDMCRITSECTINT pCritSect, void *pvKey, RT_SRC_POS_DECL, const char *pszNameFmt, va_list va)
+static int pdmR3CritSectInitOne(PVM pVM, PPDMCRITSECTINT pCritSect, void *pvKey, RT_SRC_POS_DECL,
+                                const char *pszNameFmt, va_list va)
 {
     VM_ASSERT_EMT(pVM);
@@ -459 +460 @@
     AssertReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC, false);
     Assert(pCritSect->s.Core.NativeThreadOwner == RTThreadNativeSelf());
+    Assert(!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP));
 
     /* No recursion allowed here. */
@@ -516 +518 @@
 VMMR3DECL(int) PDMR3CritSectScheduleExitEvent(PPDMCRITSECT pCritSect, RTSEMEVENT EventToSignal)
 {
+    AssertPtr(pCritSect);
+    Assert(!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP));
     Assert(EventToSignal != NIL_RTSEMEVENT);
     if (RT_UNLIKELY(!RTCritSectIsOwner(&pCritSect->s.Core)))