On 3.11.18 г. 17:39 ч., Arnd Bergmann wrote:
> On 32-bit ARM with gcc-8, I see a link error with the addition of the
> CONFIG_NO_AUTO_INLINE option:
>
> fs/btrfs/super.o: In function `btrfs_statfs':
> super.c:(.text+0x67b8): undefined reference to `__aeabi_uldivmod'
> super.c:(.text+0x67fc): undefined reference to `__aeabi_uldivmod'
> super.c:(.text+0x6858): undefined reference to `__aeabi_uldivmod'
> super.c:(.text+0x6920): undefined reference to `__aeabi_uldivmod'
> super.c:(.text+0x693c): undefined reference to `__aeabi_uldivmod'
> fs/btrfs/super.o:super.c:(.text+0x6958): more undefined references to `__aeabi_uldivmod' follow
>
> So far this is the only file that shows the behavior, so I'd propose
> to just work around it by marking the functions as 'static inline'
> that normally get inlined here.
>
> The reference to __aeabi_uldivmod comes from a div_u64() which has an
> optimization for a constant division that uses a straight '/' operator
> when the result should be known to the compiler. My interpretation is
> that as we turn off inlining, gcc still expects the result to be constant
> but fails to use that constant value.
I read this as "this is a compiler bug", no ? So you are providing a
hack around a compiler bug?
>
> Cc: Changbin Du <changbin.du@xxxxxxxxx>
> Fixes: 943b8435c3bd ("kernel hacking: add a config option to disable compiler auto-inlining")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> fs/btrfs/super.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index c3c1e7bee49d..b7af0b8936ad 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -1922,7 +1922,7 @@ static int btrfs_remount(struct super_block *sb, int *flags,
> }
>
> /* Used to sort the devices by max_avail(descending sort) */
> -static int btrfs_cmp_device_free_bytes(const void *dev_info1,
> +static inline int btrfs_cmp_device_free_bytes(const void *dev_info1,
> const void *dev_info2)
> {
> if (((struct btrfs_device_info *)dev_info1)->max_avail >
> @@ -1951,8 +1951,8 @@ static inline void btrfs_descending_sort_devices(
> * The helper to calc the free space on the devices that can be used to store
> * file data.
> */
> -static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
> - u64 *free_bytes)
> +static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
> + u64 *free_bytes)
> {
> struct btrfs_device_info *devices_info;
> struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
>
