percpu: convert flexible array initializers to use struct_size()

Use the safer macro as sparked by the long discussion in [1].

[1] https://lore.kernel.org/lkml/20200917204514.GA2880159@google.com/

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

diff --git a/mm/percpu.c b/mm/percpu.c
index 66a93f096394ab4accb21fa77867f55e702428b2..ad7a37ee74ef5f2ed8ead98c966a08f7d4e2384a 100644 (file)
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1315,8 +1315,8 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
        region_size = ALIGN(start_offset + map_size, lcm_align);
 
        /* allocate chunk */
-       alloc_size = sizeof(struct pcpu_chunk) +
-               BITS_TO_LONGS(region_size >> PAGE_SHIFT) * sizeof(unsigned long);
+       alloc_size = struct_size(chunk, populated,
+                                BITS_TO_LONGS(region_size >> PAGE_SHIFT));
        chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
        if (!chunk)
                panic("%s: Failed to allocate %zu bytes\n", __func__,
@@ -2521,8 +2521,8 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
        pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
        pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
        pcpu_atom_size = ai->atom_size;
-       pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
-               BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
+       pcpu_chunk_struct_size = struct_size(chunk, populated,
+                                            BITS_TO_LONGS(pcpu_unit_pages));
 
        pcpu_stats_save_ai(ai);