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--- libmalloc/libmalloc-374.60.3/src/magazine_tiny.c
+++ libmalloc/libmalloc-317.40.8/src/magazine_tiny.c
@@ -44,13 +44,13 @@
 {
 #if CONFIG_TINY_USES_HYPER_SHIFT
 	if (os_likely(_os_cpu_number_override == -1)) {
-		return _malloc_cpu_number() >> hyper_shift;
+		return _os_cpu_number() >> hyper_shift;
 	} else {
 		return _os_cpu_number_override >> hyper_shift;
 	}
 #else // CONFIG_SMALL_USES_HYPER_SHIFT
 	if (os_likely(_os_cpu_number_override == -1)) {
-		return _malloc_cpu_number();
+		return _os_cpu_number();
 	} else {
 		return _os_cpu_number_override;
 	}
@@ -81,11 +81,7 @@
 		if (BITARRAY_BIT(prev_header, prev_index)) {
 			return 1;
 		}
-		msize_t *prev_msize_ptr = &TINY_PREVIOUS_MSIZE(ptr);
-		// This is a speculative read of potentially in-use app memory, we need
-		// to use _malloc_read_uint16_via_rsp to avoid triggering warnings in
-		// memory diagnostic tools.
-		return _malloc_read_uint16_via_rsp(prev_msize_ptr);
+		return TINY_PREVIOUS_MSIZE(ptr);
 	}
 	// don't read possibly unmapped memory before the beginning of the region
 	return 0;
@@ -840,30 +836,18 @@
 	for (mag_index = 0; mag_index < rack->num_magazines; mag_index++) {
 		size_t index;
 		for (index = 0; index < rack->region_generation->num_regions_allocated; ++index) {
-			rack_region_lock(rack);
+			SZONE_LOCK(TINY_SZONE_FROM_RACK(rack));
 
 			region_t tiny = rack->region_generation->hashed_regions[index];
 			if (!tiny || tiny == HASHRING_REGION_DEALLOCATED) {
-				rack_region_unlock(rack);
+				SZONE_UNLOCK(TINY_SZONE_FROM_RACK(rack));
 				continue;
 			}
 
-			region_trailer_t *trailer = REGION_TRAILER_FOR_TINY_REGION(tiny);
-			// Make sure that the owning magazine doesn't try and take this out
-			// from under our feet.
-			trailer->dispose_flags |= RACK_DISPOSE_DELAY;
-			rack_region_unlock(rack);
-
 			magazine_t *mag_ptr = mag_lock_zine_for_region_trailer(rack->magazines,
-					trailer, MAGAZINE_INDEX_FOR_TINY_REGION(tiny));
-
-			// If acquiring the region lock was enough to prevent the owning
-			// magazine from deallocating the region, free it now so we don't
-			// do wasted work.
-			if (rack_region_maybe_dispose(rack, tiny, TINY_REGION_SIZE, trailer)) {
-				SZONE_MAGAZINE_PTR_UNLOCK(mag_ptr);
-				continue;
-			}
+					REGION_TRAILER_FOR_TINY_REGION(tiny),
+					MAGAZINE_INDEX_FOR_TINY_REGION(tiny));
+			SZONE_UNLOCK(TINY_SZONE_FROM_RACK(rack));
 
 			/* Ordering is important here, the magazine of a region may potentially change
 			 * during mag_lock_zine_for_region_trailer, so src_mag_index must be taken
@@ -877,11 +861,6 @@
 				continue;
 			}
 
-			if (REGION_TRAILER_FOR_TINY_REGION(tiny)->pinned_to_depot > 0) {
-				SZONE_MAGAZINE_PTR_UNLOCK(mag_ptr);
-				continue;
-			}
-
 			if (tiny == mag_ptr->mag_last_region && (mag_ptr->mag_bytes_free_at_end || mag_ptr->mag_bytes_free_at_start)) {
 				tiny_finalize_region(rack, mag_ptr);
 			}
@@ -896,7 +875,7 @@
 
 			SZONE_MAGAZINE_PTR_LOCK(tiny_depot_ptr);
 			MAGAZINE_INDEX_FOR_TINY_REGION(tiny) = DEPOT_MAGAZINE_INDEX;
-			MALLOC_ASSERT(REGION_TRAILER_FOR_TINY_REGION(tiny)->pinned_to_depot == 0);
+			REGION_TRAILER_FOR_TINY_REGION(tiny)->pinned_to_depot = 0;
 
 			size_t bytes_inplay = tiny_free_reattach_region(rack, tiny_depot_ptr, tiny);
 
@@ -1002,32 +981,22 @@
 	// Appropriate a Depot'd region that can satisfy requested msize.
 	region_trailer_t *node;
 	region_t sparse_region;
-	msize_t try_msize = msize;
 
 	while (1) {
-		sparse_region = tiny_find_msize_region(rack, depot_ptr, DEPOT_MAGAZINE_INDEX, try_msize);
+		sparse_region = tiny_find_msize_region(rack, depot_ptr, DEPOT_MAGAZINE_INDEX, msize);
 		if (NULL == sparse_region) { // Depot empty?
 			SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
 			return 0;
 		}
 
 		node = REGION_TRAILER_FOR_TINY_REGION(sparse_region);
-		if (0 == node->pinned_to_depot) {
-			// Found one!
+		if (0 >= node->pinned_to_depot) {
 			break;
 		}
 
-		// Try the next msize up - maybe the head of its free list will be in
-		// a region we can use. Once we get the region we'll still allocate the
-		// original msize.
-		try_msize++;
-
-		if (try_msize > NUM_TINY_SLOTS) {
-			// Tried all the msizes but couldn't get a usable region. Let's
-			// give up for now and we'll allocate a new region from the kernel.
-			SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
-			return 0;
-		}
+		SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+		yield();
+		SZONE_MAGAZINE_PTR_LOCK(depot_ptr);
 	}
 
 	// disconnect node from Depot
@@ -1038,7 +1007,7 @@
 
 	// Transfer ownership of the region
 	MAGAZINE_INDEX_FOR_TINY_REGION(sparse_region) = mag_index;
-	MALLOC_ASSERT(node->pinned_to_depot == 0);
+	node->pinned_to_depot = 0;
 
 	// Iterate the region putting its free entries on its new (locked) magazine's free list
 	size_t bytes_inplay = tiny_free_reattach_region(rack, tiny_mag_ptr, sparse_region);
@@ -1080,19 +1049,32 @@
 	int objects_in_use = tiny_free_detach_region(rack, depot_ptr, sparse_region);
 
 	if (0 == objects_in_use) {
-		if (!rack_region_remove(rack, sparse_region, node)) {
+		// Invalidate the hash table entry for this region with HASHRING_REGION_DEALLOCATED.
+		// Using HASHRING_REGION_DEALLOCATED preserves the collision chain, using HASHRING_OPEN_ENTRY (0) would not.
+		rgnhdl_t pSlot = hash_lookup_region_no_lock(rack->region_generation->hashed_regions,
+				rack->region_generation->num_regions_allocated,
+				rack->region_generation->num_regions_allocated_shift,
+				sparse_region);
+
+		if (NULL == pSlot) {
+			malloc_zone_error(rack->debug_flags, true, "tiny_free_try_depot_unmap_no_lock hash lookup failed: %p\n", sparse_region);
 			return NULL;
 		}
+		*pSlot = HASHRING_REGION_DEALLOCATED;
 		depot_ptr->num_bytes_in_magazine -= TINY_HEAP_SIZE;
 
+		// Atomically increment num_regions_dealloc
+#ifdef __LP64___
+		OSAtomicIncrement64(&rack->num_regions_dealloc);
+#else
+		OSAtomicIncrement32((int32_t *)&rack->num_regions_dealloc);
+#endif
+
 		// Caller will transfer ownership of the region back to the OS with no locks held
-		MAGMALLOC_DEALLOCREGION(TINY_SZONE_FROM_RACK(rack),
-				(void *)sparse_region, TINY_REGION_SIZE); // DTrace USDT Probe
+		MAGMALLOC_DEALLOCREGION(TINY_SZONE_FROM_RACK(rack), (void *)sparse_region, TINY_REGION_SIZE); // DTrace USDT Probe
 		return sparse_region;
 	} else {
-		malloc_zone_error(rack->debug_flags, true,
-				"tiny_free_try_depot_unmap_no_lock objects_in_use not zero: %d\n",
-				objects_in_use);
+		malloc_zone_error(rack->debug_flags, true, "tiny_free_try_depot_unmap_no_lock objects_in_use not zero: %d\n", objects_in_use);
 		return NULL;
 	}
 }