Re: [PATCH 29/34] net: smc: fix opencoded find_and_set_bit() in smc_wr_tx_get_free_slot_index()

Alexandra Winter
2023-11-20T08:44:38Z

On 18.11.23 16:51, Yury Norov wrote:
> The function opencodes find_and_set_bit() with a for_each() loop. Fix
> it, and make the whole function a simple almost one-liner.
>
> Signed-off-by: Yury Norov <yury.norov@gmail.com>
> ---
> net/smc/smc_wr.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c
> index 0021065a600a..b6f0cfc52788 100644
> --- a/net/smc/smc_wr.c
> +++ b/net/smc/smc_wr.c
> @@ -170,15 +170,11 @@ void smc_wr_tx_cq_handler(struct ib_cq *ib_cq, void *cq_context)
>
> static inline int smc_wr_tx_get_free_slot_index(struct smc_link *link, u32 *idx)
> {
> - *idx = link->wr_tx_cnt;
> if (!smc_link_sendable(link))
> return -ENOLINK;
> - for_each_clear_bit(*idx, link->wr_tx_mask, link->wr_tx_cnt) {
> - if (!test_and_set_bit(*idx, link->wr_tx_mask))
> - return 0;
> - }
> - *idx = link->wr_tx_cnt;
> - return -EBUSY;
> +
> + *idx = find_and_set_bit(link->wr_tx_mask, link->wr_tx_cnt);
> + return *idx < link->wr_tx_cnt ? 0 : -EBUSY;
> }
>
> /**

My understanding is that you can omit the lines with
> - *idx = link->wr_tx_cnt;
because they only apply to the error paths and you checked that the calling function
does not use the idx variable in the error cases. Do I understand this correct?

If so the removal of these 2 lines is not related to your change of using find_and_set_bit(),
do I understand that correctly?

If so, it may be worth mentioning that in the commit message.