mempool: fix returned value after counting objects

rte_mempool_xmem_usage()'s return type is ssize_t which has the same
architecture-dependent width as size_t but is signed.

On 64-bit architectures, returning a negative uint32_t value without casting
to ssize_t first does not work as intended, the sign bit is lost and the
returned value is garbage.

This commit fixes an assertion failure in testpmd on 64 bit architectures
when combining --no-huge and --mp-anon outside of Xen Dom0:

 PANIC in mempool_anon_create():
 line 170        assert "elt_num == mp->size" failed

Fixes: 148f963fb532 ("xen: core library changes")
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 01972ba010d06f5c564f270fce78e2f094f6184e..d1a02a2571fe9713e26066a1f3d994630dcf9f96 100644 (file)
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -361,7 +361,7 @@ rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num, size_t elt_sz,
        if ((n = rte_mempool_obj_iter(vaddr, elt_num, elt_sz, 1,
                        paddr, pg_num, pg_shift, mempool_lelem_iter,
                        &uv)) != elt_num) {
-               return (-n);
+               return (-(ssize_t)n);
        }
 
        uv = RTE_ALIGN_CEIL(uv, pg_sz);