Fix/simplify extent_recycle() allocation size computations.

Do not call s2u() during alloc_size computation, since any necessary
ceiling increase is taken care of later by extent_first_best_fit() -->
extent_size_quantize_ceil(), and the s2u() call may erroneously cause a
higher quantization result.

Remove an overly strict overflow check that was added in
4a7852137d8b6598fdb90ea8e1fd3bc8a8b94a3a (Fix extent_recycle()'s
cache-oblivious padding support.).

1 files changed, 5 insertions, 6 deletions

diff --git a/src/extent.c b/src/extent.c
index e190adc..4027e8b 100644
--- a/src/extent.c
+++ b/src/extent.c
@@ -405,6 +405,7 @@ extent_recycle(tsdn_t *tsdn, arena_t *arena, extent_hooks_t **r_extent_hooks,
 		malloc_mutex_assert_owner(tsdn, &arena->extents_mtx);
 	assert(new_addr == NULL || !slab);
 	assert(pad == 0 || !slab);
+	assert(alignment > 0);
 	if (config_debug && new_addr != NULL) {
 		extent_t *prev;
 
@@ -427,13 +428,11 @@ extent_recycle(tsdn_t *tsdn, arena_t *arena, extent_hooks_t **r_extent_hooks,
 		assert(prev == NULL || extent_past_get(prev) == new_addr);
 	}
 
-	alloc_size = ((new_addr != NULL) ? usize : s2u(usize +
-	    PAGE_CEILING(alignment) - PAGE)) + pad;
-	if (alloc_size > LARGE_MAXCLASS + pad || alloc_size < usize) {
-		/* Too large, possibly wrapped around. */
-		return (NULL);
-	}
 	size = usize + pad;
+	alloc_size = size + PAGE_CEILING(alignment) - PAGE;
+	/* Beware size_t wrap-around. */
+	if (alloc_size < usize)
+		return (NULL);
 	if (!locked)
 		malloc_mutex_lock(tsdn, &arena->extents_mtx);
 	extent_hooks_assure_initialized(arena, r_extent_hooks);