Re: [PATCH] spi: amlogic-spisg: drop misleading NULL check on exdesc

[Xianwei Zhao <xianwei.zhao@amlogic.com>]

Hi Stepan,

On 2026/5/7 02:35, Stepan Ionichev wrote:
> aml_spisg_setup_transfer() takes a non-NULL exdesc pointer; the
> function dereferences exdesc unconditionally later in the body to
> populate the SPI scatter-gather descriptors (tx_ccsg / rx_ccsg).
> The sole caller, aml_spisg_transfer_one_message(), always passes a
> valid pointer derived from kcalloc().
> 
> The "if (exdesc)" guard around the memset() at the start of the
> function is therefore dead and misleading -- it suggests callers
> may pass NULL when in fact they may not. smatch flags the
> inconsistency:
> 
>    drivers/spi/spi-amlogic-spisg.c:314 aml_spisg_setup_transfer()
>      error: we previously assumed 'exdesc' could be null (see line 261)
> 
> Drop the check; the unconditional memset matches the unconditional
> dereferences elsewhere in the function and removes the inconsistency
> that smatch reports.
> 
> No functional change.
> 
> Signed-off-by: Stepan Ionichev<sozdayvek@gmail.com>
> ---
>   drivers/spi/spi-amlogic-spisg.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-amlogic-spisg.c b/drivers/spi/spi-amlogic-spisg.c
> index 19c5eba41..b2a916496 100644
> --- a/drivers/spi/spi-amlogic-spisg.c
> +++ b/drivers/spi/spi-amlogic-spisg.c
> @@ -258,8 +258,7 @@ static int aml_spisg_setup_transfer(struct spisg_device *spisg,
>          int ret;
> 
>          memset(desc, 0, sizeof(*desc));
> -       if (exdesc)
> -               memset(exdesc, 0, sizeof(*exdesc));
> +       memset(exdesc, 0, sizeof(*exdesc)); >          aml_spisg_set_speed(spisg, xfer->speed_hz);
>          xfer->effective_speed_hz = spisg->effective_speed_hz;

Reviewed-by: Xianwei Zhao <xianwei.zhao@amlogic.com>