linux-kernel - Re: [PATCH 1/2] mmc: core: Drop superfluous validations in mmc_hw|sw

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Date:   Tue, 16 Feb 2021 10:32:57 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>, linux-mmc@...r.kernel.org
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Pierre Ossman <pierre@...man.eu>,
        Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mmc: core: Drop superfluous validations in
 mmc_hw|sw_reset()

On 12/02/21 3:15 pm, Ulf Hansson wrote:
> The mmc_hw|sw_reset() APIs are designed to be called solely from upper
> layers, which means drivers that operates on top of the struct mmc_card,
> like the mmc block device driver and an SDIO functional driver.
> 
> Additionally, as long as the struct mmc_host has a valid pointer to a
> struct mmc_card, the corresponding host->bus_ops pointer stays valid and
> assigned.
> 
> For these reasons, let's drop the superfluous reference counting and the
> redundant validations in mmc_hw|sw_reset().
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>

Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
> 
> Note, ideally mmc_hw|sw_reset() shall be converted to take a struct mmc_card*
> as an in-parameter, rather than the current struct mmc_host*, but that is left
> to a future/separate change.
> 
> ---
>  drivers/mmc/core/block.c |  2 +-
>  drivers/mmc/core/core.c  | 21 +--------------------
>  2 files changed, 2 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index b877f62df366..b7d3f5a73388 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -947,7 +947,7 @@ static int mmc_blk_reset(struct mmc_blk_data *md, struct mmc_host *host,
>  	md->reset_done |= type;
>  	err = mmc_hw_reset(host);
>  	/* Ensure we switch back to the correct partition */
> -	if (err != -EOPNOTSUPP) {
> +	if (err) {
>  		struct mmc_blk_data *main_md =
>  			dev_get_drvdata(&host->card->dev);
>  		int part_err;
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 1136b859ddd8..2e41fa598bd6 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2080,18 +2080,7 @@ int mmc_hw_reset(struct mmc_host *host)
>  {
>  	int ret;
>  
> -	if (!host->card)
> -		return -EINVAL;
> -
> -	mmc_bus_get(host);
> -	if (!host->bus_ops || host->bus_dead || !host->bus_ops->hw_reset) {
> -		mmc_bus_put(host);
> -		return -EOPNOTSUPP;
> -	}
> -
>  	ret = host->bus_ops->hw_reset(host);
> -	mmc_bus_put(host);
> -
>  	if (ret < 0)
>  		pr_warn("%s: tried to HW reset card, got error %d\n",
>  			mmc_hostname(host), ret);
> @@ -2104,18 +2093,10 @@ int mmc_sw_reset(struct mmc_host *host)
>  {
>  	int ret;
>  
> -	if (!host->card)
> -		return -EINVAL;
> -
> -	mmc_bus_get(host);
> -	if (!host->bus_ops || host->bus_dead || !host->bus_ops->sw_reset) {
> -		mmc_bus_put(host);
> +	if (!host->bus_ops->sw_reset)
>  		return -EOPNOTSUPP;
> -	}
>  
>  	ret = host->bus_ops->sw_reset(host);
> -	mmc_bus_put(host);
> -
>  	if (ret)
>  		pr_warn("%s: tried to SW reset card, got error %d\n",
>  			mmc_hostname(host), ret);
>