BUG/MINOR: pools: fix a possible memory leak in the lockless pool_flush()

The lockless version of pool_flush() had a leftover of the original
version causing the pool's first entry to be set to NULL at the end.
The problem is that it does this outside of any lock and in a non-
atomic way, so that any concurrent alloc+free would result in a lost
object.

The risk is low and the consequence even lower, given that pool_flush()
is only used in pool_destroy() (hence single-threaded) or by stream_free()
during a soft-stop (not the place where most allocations happen), so in
the worst case it could result in valgrind complaining on soft-stop.

The bug was introduced with the first version of the code, in 1.9, so
the fix can be backported to all stable versions.

diff --git a/src/pool.c b/src/pool.c
index 55c833a3b6cd302e957ac89105f8b63f2b247873..827cab457d5fb33018134f22dc9f59e045661331 100644 (file)
--- a/src/pool.c
+++ b/src/pool.c
@@ -303,8 +303,7 @@ void pool_flush(struct pool_head *pool)
                next = *POOL_LINK(pool, temp);
                pool_put_to_os(pool, temp);
        }
-       pool->free_list = next;
-       /* here, we should have pool->allocate == pool->used */
+       /* here, we should have pool->allocated == pool->used */
 }
 
 /*