Fix locking (syntax whoops)

Author: PascalBoeschoten

src/Driver.cxx

@@ -36,7 +36,7 @@ void freeUnusedChannelBuffers()
 {
   namespace bfs = boost::filesystem;
   InfoLogger::InfoLogger logger;
-  Pda::PdaLock lock(); // We're messing around with PDA buffers so we need this
+  Pda::PdaLock lock{}; // We're messing around with PDA buffers so we need this
 
   try {
     std::string pciPath = "/sys/bus/pci/drivers/uio_pci_dma/";

src/Pda/PdaDmaBuffer.cxx

@@ -18,7 +18,7 @@ PdaDmaBuffer::PdaDmaBuffer(PdaDevice::PdaPciDevice pciDevice, void* userBufferAd
     int dmaBufferId, bool requireHugepage) : mPciDevice(pciDevice)
 {
   // Safeguard against PDA kernel module deadlocks, since it does not like parallel buffer registration
-  PdaLock lock();
+  Pda::PdaLock lock{};
 
   try {
     // Tell PDA we're using our already allocated userspace buffer.
@@ -100,7 +100,7 @@ PdaDmaBuffer::~PdaDmaBuffer()
   // Safeguard against PDA kernel module deadlocks, since it does not like parallel buffer registration
   // NOTE: not sure if necessary for deregistration as well
   try {
-    PdaLock lock();
+    Pda::PdaLock lock{};
     PciDevice_deleteDMABuffer(mPciDevice.get(), mDmaBuffer);
   } catch (std::exception& e) {
     // Nothing to be done?

src/Pda/PdaLock.h

@@ -17,8 +17,14 @@ namespace Pda {
 /// Just hope nobody else uses PDA in parallel.
 class PdaLock
 {
-    PdaLock() : mLock("/dev/shm/alice_o2/rorc/AliceO2_roc_Pda_PdaDmaBuffer.lock", "AliceO2_roc_Pda_PdaDmaBuffer_Mutex",
-      true)
+  public:
+
+    /// Be careful you don't use it like this:
+    ///   Pda::PdaLock lock()
+    /// But rather like this:
+    ///   Pda::PdaLock lock{}
+    PdaLock(bool wait = true) : mLock("/dev/shm/alice_o2/rorc/AliceO2_roc_Pda_PdaDmaBuffer.lock",
+      "AliceO2_roc_Pda_PdaDmaBuffer_Mutex", wait)
     {
     }