linux-kernel - Re: [PATCH] scsi: cxlflash: Mark expected switch fall-throughs

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Date:   Mon, 29 Jul 2019 09:47:44 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     "Manoj N. Kumar" <manoj@...ux.ibm.com>,
        "Matthew R. Ochs" <mrochs@...ux.ibm.com>,
        Uma Krishnan <ukrishn@...ux.ibm.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] scsi: cxlflash: Mark expected switch fall-throughs

On Sun, Jul 28, 2019 at 07:21:19PM -0500, Gustavo A. R. Silva wrote:
> Mark switch cases where we are expecting to fall through.
> 
> This patch fixes the following warnings:
> 
> drivers/scsi/cxlflash/main.c: In function 'send_afu_cmd':
> drivers/scsi/cxlflash/main.c:2347:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (rc) {
>       ^
> drivers/scsi/cxlflash/main.c:2357:2: note: here
>   case -EAGAIN:
>   ^~~~
> drivers/scsi/cxlflash/main.c: In function 'term_intr':
> drivers/scsi/cxlflash/main.c:754:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (index == PRIMARY_HWQ)
>       ^
> drivers/scsi/cxlflash/main.c:756:2: note: here
>   case UNMAP_TWO:
>   ^~~~
> drivers/scsi/cxlflash/main.c:757:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    cfg->ops->unmap_afu_irq(hwq->ctx_cookie, 2, hwq);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/scsi/cxlflash/main.c:758:2: note: here
>   case UNMAP_ONE:
>   ^~~~
> drivers/scsi/cxlflash/main.c:759:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    cfg->ops->unmap_afu_irq(hwq->ctx_cookie, 1, hwq);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/scsi/cxlflash/main.c:760:2: note: here
>   case FREE_IRQ:
>   ^~~~
> drivers/scsi/cxlflash/main.c: In function 'cxlflash_remove':
> drivers/scsi/cxlflash/main.c:975:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    cxlflash_release_chrdev(cfg);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/scsi/cxlflash/main.c:976:2: note: here
>   case INIT_STATE_SCSI:
>   ^~~~
> drivers/scsi/cxlflash/main.c:978:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    scsi_remove_host(cfg->host);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/scsi/cxlflash/main.c:979:2: note: here
>   case INIT_STATE_AFU:
>   ^~~~
> drivers/scsi/cxlflash/main.c:980:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    term_afu(cfg);
>    ^~~~~~~~~~~~~
> drivers/scsi/cxlflash/main.c:981:2: note: here
>   case INIT_STATE_PCI:
>   ^~~~
> drivers/scsi/cxlflash/main.c:983:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    pci_disable_device(pdev);
>    ^~~~~~~~~~~~~~~~~~~~~~~~
> drivers/scsi/cxlflash/main.c:984:2: note: here
>   case INIT_STATE_NONE:
>   ^~~~
> drivers/scsi/cxlflash/main.c: In function 'num_hwqs_store':
> drivers/scsi/cxlflash/main.c:3018:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (cfg->state == STATE_NORMAL)
>       ^
> drivers/scsi/cxlflash/main.c:3020:2: note: here
>   default:
>   ^~~~~~~
> 
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  drivers/scsi/cxlflash/main.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
> index b1f4724efde2..93ef97af22df 100644
> --- a/drivers/scsi/cxlflash/main.c
> +++ b/drivers/scsi/cxlflash/main.c
> @@ -753,10 +753,13 @@ static void term_intr(struct cxlflash_cfg *cfg, enum undo_level level,
>  		/* SISL_MSI_ASYNC_ERROR is setup only for the primary HWQ */
>  		if (index == PRIMARY_HWQ)
>  			cfg->ops->unmap_afu_irq(hwq->ctx_cookie, 3, hwq);
> +		/* fall through */
>  	case UNMAP_TWO:
>  		cfg->ops->unmap_afu_irq(hwq->ctx_cookie, 2, hwq);
> +		/* fall through */
>  	case UNMAP_ONE:
>  		cfg->ops->unmap_afu_irq(hwq->ctx_cookie, 1, hwq);
> +		/* fall through */
>  	case FREE_IRQ:
>  		cfg->ops->free_afu_irqs(hwq->ctx_cookie);
>  		/* fall through */
> @@ -973,14 +976,18 @@ static void cxlflash_remove(struct pci_dev *pdev)
>  	switch (cfg->init_state) {
>  	case INIT_STATE_CDEV:
>  		cxlflash_release_chrdev(cfg);
> +		/* fall through */
>  	case INIT_STATE_SCSI:
>  		cxlflash_term_local_luns(cfg);
>  		scsi_remove_host(cfg->host);
> +		/* fall through */
>  	case INIT_STATE_AFU:
>  		term_afu(cfg);
> +		/* fall through */
>  	case INIT_STATE_PCI:
>  		cfg->ops->destroy_afu(cfg->afu_cookie);
>  		pci_disable_device(pdev);
> +		/* fall through */
>  	case INIT_STATE_NONE:
>  		free_mem(cfg);
>  		scsi_host_put(cfg->host);
> @@ -2353,11 +2360,11 @@ static int send_afu_cmd(struct afu *afu, struct sisl_ioarcb *rcb)
>  			cxlflash_schedule_async_reset(cfg);
>  			break;
>  		}
> -		/* fall through to retry */
> +		/* fall through - to retry */
>  	case -EAGAIN:
>  		if (++nretry < 2)
>  			goto retry;
> -		/* fall through to exit */
> +		/* fall through - to exit */
>  	default:
>  		break;
>  	}
> @@ -3017,6 +3024,7 @@ static ssize_t num_hwqs_store(struct device *dev,
>  		wait_event(cfg->reset_waitq, cfg->state != STATE_RESET);
>  		if (cfg->state == STATE_NORMAL)
>  			goto retry;
> +		/* else, fall through */
>  	default:
>  		/* Ideally should not happen */
>  		dev_err(dev, "%s: Device is not ready, state=%d\n",
> -- 
> 2.22.0
> 

-- 
Kees Cook