ITS: early continue if no seeding vertex in rof

Author: f3sch

Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx

@@ -77,6 +77,9 @@ void TrackerTraits<nLayers>::computeLayerTracklets(const int iteration, int iROF
       gsl::span<const Vertex> primaryVertices = mTrkParams[iteration].UseDiamond ? diamondSpan : mTimeFrame->getPrimaryVertices(rof0);
       const int startVtx{iVertex >= 0 ? iVertex : 0};
       const int endVtx{iVertex >= 0 ? o2::gpu::CAMath::Min(iVertex + 1, static_cast<int>(primaryVertices.size())) : static_cast<int>(primaryVertices.size())};
+      if (endVtx - startVtx <= 0) {
+        continue;
+      }
       int minRof = o2::gpu::CAMath::Max(startROF, rof0 - mTrkParams[iteration].DeltaROF);
       int maxRof = o2::gpu::CAMath::Min(endROF - 1, rof0 + mTrkParams[iteration].DeltaROF);