[Lldb-commits] [PATCH] D46733: Add a lock to PlatformPOSIX::DoLoadImage

[Frederic Riss via Phabricator via lldb-commits]

friss created this revision.
friss added a reviewer: jingham.
Herald added a subscriber: emaste.

Multiple threads could be calling into DoLoadImage concurrently,
only one should be allowed to create the UtilityFunction.


https://reviews.llvm.org/D46733

Files:
  source/Plugins/Platform/POSIX/PlatformPOSIX.cpp


Index: source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
===================================================================
--- source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
+++ source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
@@ -1036,17 +1036,23 @@
   thread_sp->CalculateExecutionContext(exe_ctx);
 
   Status utility_error;
-  
-  // The UtilityFunction is held in the Process.  Platforms don't track the
-  // lifespan of the Targets that use them, we can't put this in the Platform.
-  UtilityFunction *dlopen_utility_func 
-      = process->GetLoadImageUtilityFunction(this);
+  UtilityFunction *dlopen_utility_func;
   ValueList arguments;
   FunctionCaller *do_dlopen_function = nullptr;
   
-  if (!dlopen_utility_func) {
-    // Make the UtilityFunction:
-    dlopen_utility_func = MakeLoadImageUtilityFunction(exe_ctx, error);
+  // Multiple threads could be calling into DoLoadImage concurrently,
+  // only one should be allowed to create the UtilityFunction.
+  {
+    static std::mutex do_dlopen_mutex;
+    std::lock_guard<std::mutex> lock(do_dlopen_mutex);
+
+    // The UtilityFunction is held in the Process.  Platforms don't track the
+    // lifespan of the Targets that use them, we can't put this in the 
Platform.
+    dlopen_utility_func = process->GetLoadImageUtilityFunction(this);
+    if (!dlopen_utility_func) {
+      // Make the UtilityFunction:
+      dlopen_utility_func = MakeLoadImageUtilityFunction(exe_ctx, error);
+    }
   }
   // If we couldn't make it, the error will be in error, so we can exit here.
   if (!dlopen_utility_func)



Index: source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
===================================================================
--- source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
+++ source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
@@ -1036,17 +1036,23 @@
   thread_sp->CalculateExecutionContext(exe_ctx);
 
   Status utility_error;
-  
-  // The UtilityFunction is held in the Process.  Platforms don't track the
-  // lifespan of the Targets that use them, we can't put this in the Platform.
-  UtilityFunction *dlopen_utility_func 
-      = process->GetLoadImageUtilityFunction(this);
+  UtilityFunction *dlopen_utility_func;
   ValueList arguments;
   FunctionCaller *do_dlopen_function = nullptr;
   
-  if (!dlopen_utility_func) {
-    // Make the UtilityFunction:
-    dlopen_utility_func = MakeLoadImageUtilityFunction(exe_ctx, error);
+  // Multiple threads could be calling into DoLoadImage concurrently,
+  // only one should be allowed to create the UtilityFunction.
+  {
+    static std::mutex do_dlopen_mutex;
+    std::lock_guard<std::mutex> lock(do_dlopen_mutex);
+
+    // The UtilityFunction is held in the Process.  Platforms don't track the
+    // lifespan of the Targets that use them, we can't put this in the Platform.
+    dlopen_utility_func = process->GetLoadImageUtilityFunction(this);
+    if (!dlopen_utility_func) {
+      // Make the UtilityFunction:
+      dlopen_utility_func = MakeLoadImageUtilityFunction(exe_ctx, error);
+    }
   }
   // If we couldn't make it, the error will be in error, so we can exit here.
   if (!dlopen_utility_func)

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