[PATCH] percpu: convert flexible array initializers to use struct_size()

From: Dennis Zhou
Date: Fri Oct 30 2020 - 16:59:22 EST


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

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

Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx>
---
I'll apply it to for-5.10-fixes.

mm/percpu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 66a93f096394..ad7a37ee74ef 100644
--- 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);

--
2.29.1.341.ge80a0c044ae-goog