Re: [net-next,V0.5,5/5] eth: fbnic: Update RX mbox timeout value

[Jakub Kicinski <kuba@kernel.org>]

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---
eth: fbnic: Update RX mbox timeout value

This commit unifies timeout values for mailbox RX read requests and
introduces a wrapper function fbnic_mbx_wait_for_cmpl() to simplify the
completion wait calls.

> diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_fw.h b/drivers/net/ethernet/meta/fbnic/fbnic_fw.h
> index 1ecd777aaada..6b3fb163d381 100644
> --- a/drivers/net/ethernet/meta/fbnic/fbnic_fw.h
> +++ b/drivers/net/ethernet/meta/fbnic/fbnic_fw.h

[ ... ]

> +static inline bool fbnic_mbx_wait_for_cmpl(struct fbnic_fw_completion *cmpl)
> +{
> +	return wait_for_completion_timeout(&cmpl->done,
> +					   FBNIC_MBX_RX_TO_SEC * HZ);
> +}

The wrapper returns the result of wait_for_completion_timeout() which is
non-zero (remaining jiffies) on success and zero on timeout.

> diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_devlink.c b/drivers/net/ethernet/meta/fbnic/fbnic_devlink.c
> index b62b1d5b1453..193f554717b3 100644
> --- a/drivers/net/ethernet/meta/fbnic/fbnic_devlink.c
> +++ b/drivers/net/ethernet/meta/fbnic/fbnic_devlink.c
> @@ -178,7 +178,7 @@ fbnic_flash_start(struct fbnic_dev *fbd, struct pldmfw_component *component)
>  		goto cmpl_free;
>
>  	/* Wait for firmware to ack firmware upgrade start */
> -	if (wait_for_completion_timeout(&cmpl->done, 10 * HZ))
> +	if (!fbnic_mbx_wait_for_cmpl(cmpl))
>  		err = cmpl->result;
>  	else
>  		err = -ETIMEDOUT;

Is the condition inverted here? The original code enters the first branch
when wait_for_completion_timeout() returns non-zero (success). The new
code enters the first branch when fbnic_mbx_wait_for_cmpl() returns zero
(timeout) due to the added negation. This would cause successful
completions to return -ETIMEDOUT.

[ ... ]

> @@ -447,7 +447,7 @@ static int fbnic_fw_reporter_dump(struct devlink_health_reporter *reporter,
>  				goto cmpl_cleanup;
>  		}
>
> -		if (wait_for_completion_timeout(&fw_cmpl->done, 2 * HZ)) {
> +		if (!fbnic_mbx_wait_for_cmpl(fw_cmpl)) {
>  			reinit_completion(&fw_cmpl->done);
>  		} else {
>  			NL_SET_ERR_MSG_FMT_MOD(extack,

Similar issue in this loop - the original code calls reinit_completion()
on success (non-zero return) and goes to error handling on timeout (zero
return). With the added negation, success now triggers the error path
setting err = -ETIMEDOUT, while timeout triggers reinit_completion().