rnatm

commit c8781620c50e9d00d34a49e408a2bd2585ba1fb3
parent b1f3a65edfd06cceed50a8cc68cf8b6356c58ceb
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Fri, 20 Oct 2023 15:35:38 +0200

Fix voxelization deadlock

Partitions that do not overlap the atmosphere grid were not released as
expected, resulting in a deadlock when there were no empty partitions
left for voxelization threads.

Diffstat:
M
src/rnatm_voxel_partition.c
 | 
9
++++++++-

1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/rnatm_voxel_partition.c b/src/rnatm_voxel_partition.c
@@ -122,6 +122,7 @@ partition_init
   partition->id = SIZE_MAX;
   partition->tile = NULL;
   partition->pool = pool;
+  partition->ref = 0;
 }
 
 static void
@@ -251,11 +252,17 @@ partition_free(struct partition* partition)
 
   pool = partition->pool;
 
-  if(ATOMIC_DECR(&partition->ref) != 0)
+  /* The partition reference counter can be zero before being decremented: it is
+   * initialized to the voxel width once the partition has been commited. So, if
+   * the partition is released before any commit (for example, when it doesn't
+   * overlap the atmosphere grid), it can be negative after it has been
+   * decremented */
+  if(ATOMIC_DECR(&partition->ref) > 0)
     return; /* The partition is still referenced */
 
   mutex_lock(pool->mutex);
   list_move_tail(&partition->node, &pool->parts_free); /* Free the partition */
+  partition->ref = 0; /* Reset to 0 rather than letting a negative value */
   if(partition->tile) { /* Free the reserved tile */
     list_move_tail(&partition->tile->node, &pool->tiles_free);
     partition->tile = NULL;