[libxslt] 595612 Try to fix some locking problems

[Daniel Veillard <veillard src gnome org>]

commit 2e8defa7ccef2f76fb1cbfe9e9673d8e4b6cf1d6
Author: Daniel Veillard <veillard redhat com>
Date:   Sun Sep 20 11:51:52 2009 +0200

    595612 Try to fix some locking problems
    
    * libxslt/extensions.c: there were still cases where the normal
      code path could led to trying to mtake again the extension lock
      go over all entry points of the module and clean things up

 libxslt/extensions.c |   34 ++++++++++++++++++++++------------
 1 files changed, 22 insertions(+), 12 deletions(-)
---
diff --git a/libxslt/extensions.c b/libxslt/extensions.c
index ebb81f5..6187b7a 100644
--- a/libxslt/extensions.c
+++ b/libxslt/extensions.c
@@ -313,8 +313,6 @@ typedef void (*exsltRegisterFunction) (void);
  * by LIBXSLT_DEFAULT_PLUGINS_PATH() which is determined at
  * compile time.
  *
- * Always called with xsltExtMutex lock taken.
- *
  * Returns 0 if successful, -1 in case of error. 
  */
 
@@ -550,10 +548,14 @@ xsltRegisterExtPrefix(xsltStylesheetPtr style,
     if (xsltExtensionsHash != NULL) {
         xsltExtModulePtr module;
 
+        xmlMutexLock(xsltExtMutex);
         module = xmlHashLookup(xsltExtensionsHash, URI);
+        xmlMutexUnlock(xsltExtMutex);
         if (NULL == module) {
             if (!xsltExtModuleRegisterDynamic(URI)) {
+                xmlMutexLock(xsltExtMutex);
                 module = xmlHashLookup(xsltExtensionsHash, URI);
+                xmlMutexUnlock(xsltExtMutex);
             }
         }
         if (module != NULL) {
@@ -1669,18 +1671,13 @@ xsltExtElementLookup(xsltTransformContextPtr ctxt,
     if ((name == NULL) || (URI == NULL))
         return (NULL);
 
-    xmlMutexLock(xsltExtMutex);
-
     if ((ctxt != NULL) && (ctxt->extElements != NULL)) {
         XML_CAST_FPTR(ret) = xmlHashLookup2(ctxt->extElements, name, URI);
         if (ret != NULL) {
-            xmlMutexUnlock(xsltExtMutex);
             return(ret);
         }
     }
 
-    xmlMutexUnlock(xsltExtMutex);
-
     ret = xsltExtModuleElementLookup(name, URI);
 
     return (ret);
@@ -1707,19 +1704,23 @@ xsltExtModuleElementLookup(const xmlChar * name, const xmlChar * URI)
 
     ext = (xsltExtElementPtr) xmlHashLookup2(xsltElementsHash, name, URI);
 
+    xmlMutexUnlock(xsltExtMutex);
+
     /*
      * if function lookup fails, attempt a dynamic load on
      * supported platforms
      */
     if (NULL == ext) {
         if (!xsltExtModuleRegisterDynamic(URI)) {
+            xmlMutexLock(xsltExtMutex);
+
             ext = (xsltExtElementPtr)
 	          xmlHashLookup2(xsltElementsHash, name, URI);
+
+            xmlMutexUnlock(xsltExtMutex);
         }
     }
 
-    xmlMutexUnlock(xsltExtMutex);
-
     if (ext == NULL)
         return (NULL);
     return (ext->transform);
@@ -1747,13 +1748,18 @@ xsltExtModuleElementPreComputeLookup(const xmlChar * name,
 
     ext = (xsltExtElementPtr) xmlHashLookup2(xsltElementsHash, name, URI);
 
+    xmlMutexUnlock(xsltExtMutex);
+
     if (ext == NULL) {
         if (!xsltExtModuleRegisterDynamic(URI)) {
+            xmlMutexLock(xsltExtMutex);
+
             ext = (xsltExtElementPtr)
 	          xmlHashLookup2(xsltElementsHash, name, URI);
+
+            xmlMutexUnlock(xsltExtMutex);
         }
     }
-    xmlMutexUnlock(xsltExtMutex);
 
     if (ext == NULL)
         return (NULL);
@@ -1856,15 +1862,19 @@ xsltExtModuleTopLevelLookup(const xmlChar * name, const xmlChar * URI)
 
     XML_CAST_FPTR(ret) = xmlHashLookup2(xsltTopLevelsHash, name, URI);
 
+    xmlMutexUnlock(xsltExtMutex);
+
     /* if lookup fails, attempt a dynamic load on supported platforms */
     if (NULL == ret) {
         if (!xsltExtModuleRegisterDynamic(URI)) {
+            xmlMutexLock(xsltExtMutex);
+
             XML_CAST_FPTR(ret) = xmlHashLookup2(xsltTopLevelsHash, name, URI);
+
+            xmlMutexUnlock(xsltExtMutex);
         }
     }
 
-    xmlMutexUnlock(xsltExtMutex);
-
     return (ret);
 }