Address comments

Signed-off-by: Sergey Semenov <sergey.semenov@intel.com>

Author: sergey-semenov

sycl/source/detail/program_impl.cpp

@@ -39,16 +39,34 @@ program_impl::program_impl(
     throw runtime_error("Non-empty vector of programs expected",
                         PI_INVALID_VALUE);
   }
+
+  // Sort the programs to avoid deadlocks due to locking multiple mutexes &
+  // verify that all programs are unique.
+  std::sort(ProgramList.begin(), ProgramList.end(),
+            [](const shared_ptr_class<program_impl> &A,
+               const shared_ptr_class<program_impl> &B) {
+              return A.get() < B.get();
+            });
+  auto It = std::unique(ProgramList.begin(), ProgramList.end(),
+                        [](const shared_ptr_class<program_impl> &A,
+                           const shared_ptr_class<program_impl> &B) {
+                          return A.get() == B.get();
+                        });
+  if (It != ProgramList.end()) {
+    throw runtime_error("Attempting to link a program with itself",
+                        PI_INVALID_PROGRAM);
+  }
+
   MContext = ProgramList[0]->MContext;
   MDevices = ProgramList[0]->MDevices;
   vector_class<device> DevicesSorted;
   if (!is_host()) {
     DevicesSorted = sort_devices_by_cl_device_id(MDevices);
   }
   check_device_feature_support<info::device::is_linker_available>(MDevices);
-  vector_class<std::unique_lock<std::mutex>> Locks;
+  vector_class<unique_ptr_class<std::lock_guard<std::mutex>>> Locks;
   for (const auto &Prg : ProgramList) {
-    Locks.emplace_back(Prg->MMutex);
+    Locks.emplace_back(new std::lock_guard<std::mutex>(Prg->MMutex));
     Prg->throw_if_state_is_not(program_state::compiled);
     if (Prg->MContext != MContext) {
       throw invalid_object_error(
@@ -187,7 +205,7 @@ cl_program program_impl::get() const {
 void program_impl::compile_with_kernel_name(string_class KernelName,
                                             string_class CompileOptions,
                                             OSModuleHandle M) {
-  std::unique_lock<std::mutex> Lock(MMutex);
+  std::lock_guard<std::mutex> Lock(MMutex);
   throw_if_state_is_not(program_state::none);
   MProgramModuleHandle = M;
   if (!is_host()) {
@@ -199,7 +217,7 @@ void program_impl::compile_with_kernel_name(string_class KernelName,
 
 void program_impl::compile_with_source(string_class KernelSource,
                                        string_class CompileOptions) {
-  std::unique_lock<std::mutex> Lock(MMutex);
+  std::lock_guard<std::mutex> Lock(MMutex);
   throw_if_state_is_not(program_state::none);
   // TODO should it throw if it's host?
   if (!is_host()) {
@@ -212,7 +230,7 @@ void program_impl::compile_with_source(string_class KernelSource,
 void program_impl::build_with_kernel_name(string_class KernelName,
                                           string_class BuildOptions,
                                           OSModuleHandle Module) {
-  std::unique_lock<std::mutex> Lock(MMutex);
+  std::lock_guard<std::mutex> Lock(MMutex);
   throw_if_state_is_not(program_state::none);
   MProgramModuleHandle = Module;
   if (!is_host()) {
@@ -233,7 +251,7 @@ void program_impl::build_with_kernel_name(string_class KernelName,
 
 void program_impl::build_with_source(string_class KernelSource,
                                      string_class BuildOptions) {
-  std::unique_lock<std::mutex> Lock(MMutex);
+  std::lock_guard<std::mutex> Lock(MMutex);
   throw_if_state_is_not(program_state::none);
   // TODO should it throw if it's host?
   if (!is_host()) {
@@ -244,7 +262,7 @@ void program_impl::build_with_source(string_class KernelSource,
 }
 
 void program_impl::link(string_class LinkOptions) {
-  std::unique_lock<std::mutex> Lock(MMutex);
+  std::lock_guard<std::mutex> Lock(MMutex);
   throw_if_state_is_not(program_state::compiled);
   if (!is_host()) {
     check_device_feature_support<info::device::is_linker_available>(MDevices);