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SubjectRe: [PATCH] net: macb: Remove redundant assignment to w0
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On 29/04/2021 at 12:26, Jiapeng Chong wrote:
> Variable w0 is set to zero but these values is not used as it is
> overwritten later on, hence redundant assignment can be removed.
>
> Cleans up the following clang-analyzer warning:
>
> drivers/net/ethernet/cadence/macb_main.c:3265:3: warning: Value stored
> to 'w0' is never read [clang-analyzer-deadcode.DeadStores].
>
> drivers/net/ethernet/cadence/macb_main.c:3251:3: warning: Value stored
> to 'w0' is never read [clang-analyzer-deadcode.DeadStores].
>
> Reported-by: Abaci Robot <abaci@linux.alibaba.com>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>

NACK: there seems to be a massive bug in this code as I have the strong
feeling that '=' must be replaces by '|=' in subsequent assignment of
w0, W1... otherwise I don't understand the meaning of all this!

I don't know how RX filtering must be done in this controller neither
how to test it so if nobody steps in to fix this, I'll probably have to
do a patch based on datasheet only.

Please comment if you have a view on this.

Best regards,
Nicolas

> ---
> drivers/net/ethernet/cadence/macb_main.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 0f6a6cb..741b2e3 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -3248,7 +3248,6 @@ static void gem_prog_cmp_regs(struct macb *bp, struct ethtool_rx_flow_spec *fs)
> /* ignore field if any masking set */
> if (tp4sp_m->ip4src == 0xFFFFFFFF) {
> /* 1st compare reg - IP source address */
> - w0 = 0;
> w1 = 0;
> w0 = tp4sp_v->ip4src;
> w1 = GEM_BFINS(T2DISMSK, 1, w1); /* 32-bit compare */
> @@ -3262,7 +3261,6 @@ static void gem_prog_cmp_regs(struct macb *bp, struct ethtool_rx_flow_spec *fs)
> /* ignore field if any masking set */
> if (tp4sp_m->ip4dst == 0xFFFFFFFF) {
> /* 2nd compare reg - IP destination address */
> - w0 = 0;
> w1 = 0;
> w0 = tp4sp_v->ip4dst;
> w1 = GEM_BFINS(T2DISMSK, 1, w1); /* 32-bit compare */
> --
> 1.8.3.1
>


--
Nicolas Ferre

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