Re: [RFC PATCH 6/7] tpm: add __always_inline for tpm_is_hwrng_enabled

[Jarkko Sakkinen <jarkko@kernel.org>]

On Fri, Apr 11, 2025 at 06:54:54PM +0800, Chen Linxuan wrote:
> From: Winston Wen <wentao@uniontech.com>
> 
> On x86_64 with gcc version 13.3.0, I compile kernel with:

Use passive:

"Presume that kernel is compiled for x86_64 with gcc version 13.3.0:"

> 
>   make defconfig
>   ./scripts/kconfig/merge_config.sh .config <(
>     echo CONFIG_TCG_TPM=y
>     echo CONFIG_HW_RANDOM=m
>   )
>   make KCFLAGS="-fno-inline-small-functions -fno-inline-functions-called-once"
> 
> Then I get a link error:

"This results a link error:"

> 
>   ld: vmlinux.o: in function `tpm_add_hwrng':
>   tpm-chip.c:(.text+0x6c5924): undefined reference to `hwrng_register'
>   ld: vmlinux.o: in function `tpm_chip_unregister':
>   (.text+0x6c5bc9): undefined reference to `hwrng_unregister'
>   ld: vmlinux.o: in function `tpm_chip_register':
>   (.text+0x6c5c9b): undefined reference to `hwrng_unregister'

The resolution is lacking i.e., why adding __always_inline addresses
the linking problem.

> 
> Signed-off-by: Winston Wen <wentao@uniontech.com>
> Co-Developed-by: Chen Linxuan <chenlinxuan@uniontech.com>
> Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
> ---
>  drivers/char/tpm/tpm-chip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index e25daf2396d3..48cc74d84247 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -534,7 +534,7 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
>  	return tpm_get_random(chip, data, max);
>  }
>  
> -static bool tpm_is_hwrng_enabled(struct tpm_chip *chip)
> +static __always_inline bool tpm_is_hwrng_enabled(struct tpm_chip *chip)
>  {
>  	if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))
>  		return false;
> -- 
> 2.48.1
> 

BR, Jarkko