Re: [PATCH] net: tg3: tidy up loop, remove need to compute off with a multiply

From: Joe Perches
Date: Fri May 08 2020 - 19:21:52 EST


On Fri, 2020-05-08 at 23:53 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> Currently the value for 'off' is computed using a multiplication and
> a couple of statements later off is being incremented by len and
> this value is never read. Clean up the code by removing the
> multiplication and just increment off by len on each iteration. Also
> use len instead of TG3_OCIR_LEN.

I think this is a lot harder to read.

> diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
[]
> @@ -10798,16 +10798,14 @@ static int tg3_init_hw(struct tg3 *tp, bool reset_phy)
> static void tg3_sd_scan_scratchpad(struct tg3 *tp, struct tg3_ocir *ocir)
> {
> int i;
> + u32 off, len = TG3_OCIR_LEN;
>
> - for (i = 0; i < TG3_SD_NUM_RECS; i++, ocir++) {
> - u32 off = i * TG3_OCIR_LEN, len = TG3_OCIR_LEN;
> -
> + for (i = 0, off = 0; i < TG3_SD_NUM_RECS; i++, ocir++, off += len) {
> tg3_ape_scratchpad_read(tp, (u32 *) ocir, off, len);
> - off += len;
>
> if (ocir->signature != TG3_OCIR_SIG_MAGIC ||
> !(ocir->version_flags & TG3_OCIR_FLAG_ACTIVE))
> - memset(ocir, 0, TG3_OCIR_LEN);
> + memset(ocir, 0, len);
> }
> }

My preference would be for

{
int i;
u32 off = 0;

for (i = 0; i < TG3_SD_NUM_RECS; i++) {
tg3_ape_scratchpad_read(tp, (u32 *)ocir, off, TC3_OCIR_LEN);

if (ocir->signature != TG3_OCIR_SIG_MAGIC ||
!(ocir->version_flags & TG3_OCIR_FLAG_ACTIVE))
memset(ocir, 0, TG3_OCIR_LEN);

off += TG3_OCIR_LEN;
ocir++;
}