RE: [PATCH 3/8] mmc: core: remove BUG_ONs from mmc

[Venu Byravarasu <vbyravarasu@nvidia.com>]

> -----Original Message-----
> From: linux-mmc-owner@vger.kernel.org [mailto:linux-mmc-
> owner@vger.kernel.org] On Behalf Of Shawn Lin
> Sent: Wednesday, November 02, 2016 12:56 PM
> To: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: linux-mmc@vger.kernel.org; Shawn Lin <shawn.lin@rock-chips.com>
> Subject: [PATCH 3/8] mmc: core: remove BUG_ONs from mmc
> 
> BUG_ONs doesn't help anything except for stop the system from running. If it
> occurs, it implies we should deploy proper error handling for that. So this patch is
> gonna discard these meaningless BUG_ONs and deploy error handling if needed.
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> ---
> 
>  drivers/mmc/core/mmc.c     | 14 --------------
>  drivers/mmc/core/mmc_ops.c | 17 -----------------
>  2 files changed, 31 deletions(-)
> 
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index
> e811bd9..4763a35 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1464,7 +1464,6 @@ static int mmc_init_card(struct mmc_host *host, u32
> ocr,
>  	u32 cid[4];
>  	u32 rocr;
> 
> -	BUG_ON(!host);

Instead of just removing BUG_ON, it would be worth adding null check and
return from here graciously as you mentioned in patch commit message,
without which next instruction below may crash if host == NULL.

Similar is the case with other removals below.

>  	WARN_ON(!host->claimed);
> 
>  	/* Set correct bus mode for MMC before attempting init */ @@ -1854,9
> +1853,6 @@ static int mmc_poweroff_notify(struct mmc_card *card, unsigned int
> notify_type)
>   */
>  static void mmc_remove(struct mmc_host *host)  {
> -	BUG_ON(!host);
> -	BUG_ON(!host->card);
> -
>  	mmc_remove_card(host->card);
>  	host->card = NULL;
>  }
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