Messages in this thread Patch in this message | | | From | Matthew Weber <> | Subject | [PATCH] kfifo: DECLARE_KIFO_PTR(fifo, u64) does not work on arm 32 bit | Date | Thu, 8 Jul 2021 10:23:41 -0500 |
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From: Sean Young <sean@mess.org>
If you try to store u64 in a kfifo (or a struct with u64 members), then the buf member of __STRUCT_KFIFO_PTR will cause 4 bytes padding due to alignment (note that struct __kfifo is 20 bytes on 32 bit).
That in turn causes the __is_kfifo_ptr() to fail, which is caught by kfifo_alloc(), which now returns EINVAL.
So, ensure that __is_kfifo_ptr() compares to the right structure.
Signed-off-by: Sean Young <sean@mess.org> Acked-by: Stefani Seibold <stefani@seibold.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Matthew Weber <matthew.weber@collins.com> ---
This patch originally made it into 4.16 as 8a866fee3909c49738e1c4429a8d2b9bf27e015d but is a bug on at least 4.14 for any 32bit system(PPC/ARM/...) using kfifo with u64 datatypes.
Please add to linux-4.14.y for the next LTS tag. (Below patch is a cherry-pick of the commit onto linux-4.14.y and was verified on 32bit hardware.)
--- include/linux/kfifo.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index 41eb6fdf87a8..86b5fb08e96c 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -113,7 +113,8 @@ struct kfifo_rec_ptr_2 __STRUCT_KFIFO_PTR(unsigned char, 2, void); * array is a part of the structure and the fifo type where the array is * outside of the fifo structure. */ -#define __is_kfifo_ptr(fifo) (sizeof(*fifo) == sizeof(struct __kfifo)) +#define __is_kfifo_ptr(fifo) \ + (sizeof(*fifo) == sizeof(STRUCT_KFIFO_PTR(typeof(*(fifo)->type)))) /** * DECLARE_KFIFO_PTR - macro to declare a fifo pointer object -- 2.17.1
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