netdev - Re: [PATCH v3 31/35] net: smc: optimize smc_wr_tx_get_free_slot

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Date: Tue, 12 Dec 2023 21:26:53 +0800
From: Wen Gu <guwen@...ux.alibaba.com>
To: Yury Norov <yury.norov@...il.com>, linux-kernel@...r.kernel.org,
 Karsten Graul <kgraul@...ux.ibm.com>, Wenjia Zhang <wenjia@...ux.ibm.com>,
 Jan Karcher <jaka@...ux.ibm.com>, "D. Wythe" <alibuda@...ux.alibaba.com>,
 Tony Lu <tonylu@...ux.alibaba.com>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, linux-s390@...r.kernel.org,
 netdev@...r.kernel.org
Cc: Jan Kara <jack@...e.cz>, Mirsad Todorovac
 <mirsad.todorovac@....unizg.hr>, Matthew Wilcox <willy@...radead.org>,
 Rasmus Villemoes <linux@...musvillemoes.dk>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
 Alexey Klimov <klimov.linux@...il.com>, Bart Van Assche
 <bvanassche@....org>, Sergey Shtylyov <s.shtylyov@....ru>,
 Alexandra Winter <wintera@...ux.ibm.com>
Subject: Re: [PATCH v3 31/35] net: smc: optimize
 smc_wr_tx_get_free_slot_index()

On 2023/12/12 10:27, Yury Norov wrote:

> Simplify the function by using find_and_set_bit() and make it a simple
> almost one-liner.
> 
> While here, drop explicit initialization of *idx, because it's already
> initialized by the caller in case of ENOLINK, or set properly with
> ->wr_tx_mask, if nothing is found, in case of EBUSY.
> 
> CC: Tony Lu <tonylu@...ux.alibaba.com>
> Signed-off-by: Yury Norov <yury.norov@...il.com>
> Reviewed-by: Alexandra Winter <wintera@...ux.ibm.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;
>   }
>   
>   /**

Thank you! Yury.

Reviewed-by: Wen Gu <guwen@...ux.alibaba.com>