linux-kernel - Re: [PATCH 2/3] Staging: dgnc: Use goto for error handling

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Message-ID: <55006F4A.70805@gmail.com>
Date:	Wed, 11 Mar 2015 18:37:30 +0200
From:	Giedrius Statkevičius 
	<giedrius.statkevicius@...il.com>
To:	Quentin Lambert <lambert.quentin@...il.com>,
	Lidza Louina <lidza.louina@...il.com>,
	Mark Hounschell <markh@...pro.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	devel@...verdev.osuosl.org, driverdev-devel@...uxdriverproject.org,
	kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] Staging: dgnc: Use goto for error handling

On 2015.03.11 16:04, Quentin Lambert wrote:
> This patch introduces goto statments for error handling
> and in cases where a lock needs to be released.
> 
> A simplified version of the semantic patch that finds this problem is as
> follows: (http://coccinelle.lip6.fr)
> 
> @candidates exists@
> identifier f, label;
> statement s;
> position p1, p2, p3;
> @@
> 
>   f@p1(...) {
>   ...when any
> 
>     if@p2(...) {
>     ...when any
>       s
> 
>       return@p3 ...;
>     }
>   ...when any
>   }
> 
> @good1 exists@
> identifier candidates.f, candidates.label;
> statement candidates.s;
> position candidates.p1, candidates.p2;
> @@
> 
>   f@p1(...) {
>   ...when any
> 
>     if(...) {
>     ...when any
>       s
>       return ...;
>     }
>     ...when any
> 
>     if@p2(...) {...}
>   ...when any
>  }
> 
> @depends on good1@
> identifier candidates.f, candidates.label;
> position candidates.p1, candidates.p3;
> @@
> 
>    f@p1(...) {
>    ...when any
> *  return@p3 ...;
>   }
> 
> Signed-off-by: Quentin Lambert <lambert.quentin@...il.com>
> ---
>  drivers/staging/dgnc/dgnc_cls.c    | 19 +++++++------------
>  drivers/staging/dgnc/dgnc_driver.c | 14 +++-----------
>  drivers/staging/dgnc/dgnc_neo.c    | 30 ++++++++++++------------------
>  3 files changed, 22 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/staging/dgnc/dgnc_cls.c b/drivers/staging/dgnc/dgnc_cls.c
> index bedc522..02f19f1 100644
> --- a/drivers/staging/dgnc/dgnc_cls.c
> +++ b/drivers/staging/dgnc/dgnc_cls.c
> @@ -1029,22 +1029,16 @@ static void cls_copy_data_from_queue_to_uart(struct channel_t *ch)
>  	spin_lock_irqsave(&ch->ch_lock, flags);
>  
>  	/* No data to write to the UART */
> -	if (ch->ch_w_tail == ch->ch_w_head) {
> -		spin_unlock_irqrestore(&ch->ch_lock, flags);
> -		return;
> -	}
> +	if (ch->ch_w_tail == ch->ch_w_head)
> +		goto exit_unlock;
>  
>  	/* If port is "stopped", don't send any data to the UART */
>  	if ((ch->ch_flags & CH_FORCED_STOP) ||
> -				 (ch->ch_flags & CH_BREAK_SENDING)) {
> -		spin_unlock_irqrestore(&ch->ch_lock, flags);
> -		return;
> -	}
> +				 (ch->ch_flags & CH_BREAK_SENDING))
> +		goto exit_unlock;
>  
> -	if (!(ch->ch_flags & (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM))) {
> -		spin_unlock_irqrestore(&ch->ch_lock, flags);
> -		return;
> -	}
> +	if (!(ch->ch_flags & (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM)))
> +		goto exit_unlock;
>  
>  	n = 32;
>  
> @@ -1094,6 +1088,7 @@ static void cls_copy_data_from_queue_to_uart(struct channel_t *ch)
>  	if (len_written > 0)
>  		ch->ch_flags &= ~(CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
>  
> +exit_unlock:
>  	spin_unlock_irqrestore(&ch->ch_lock, flags);
>  }
>  
> diff --git a/drivers/staging/dgnc/dgnc_driver.c b/drivers/staging/dgnc/dgnc_driver.c
> index b7fd2bf..9387a0e 100644
> --- a/drivers/staging/dgnc/dgnc_driver.c
> +++ b/drivers/staging/dgnc/dgnc_driver.c
> @@ -572,30 +572,19 @@ static int dgnc_found_board(struct pci_dev *pdev, int id)
>  
>  	rc = dgnc_tty_register(brd);
>  	if (rc < 0) {
> -		dgnc_tty_uninit(brd);
>  		pr_err(DRVSTR ": Can't register tty devices (%d)\n", rc);
> -		brd->state = BOARD_FAILED;
> -		brd->dpastatus = BD_NOFEP;
>  		goto failed;
>  	}
>  
>  	rc = dgnc_finalize_board_init(brd);
>  	if (rc < 0) {
> -		dgnc_tty_uninit(brd);
>  		pr_err(DRVSTR ": Can't finalize board init (%d)\n", rc);
> -		brd->state = BOARD_FAILED;
> -		brd->dpastatus = BD_NOFEP;
> -
>  		goto failed;
>  	}
>  
>  	rc = dgnc_tty_init(brd);
>  	if (rc < 0) {
> -		dgnc_tty_uninit(brd);
>  		pr_err(DRVSTR ": Can't init tty devices (%d)\n", rc);
> -		brd->state = BOARD_FAILED;
> -		brd->dpastatus = BD_NOFEP;
> -
>  		goto failed;
>  	}
>  
> @@ -629,6 +618,9 @@ static int dgnc_found_board(struct pci_dev *pdev, int id)
>  	return 0;
>  
>  failed:
> +	dgnc_tty_uninit(brd);
> +	brd->state = BOARD_FAILED;
> +	brd->dpastatus = BD_NOFEP;
You'll probably have to remake this patch without this change because a
patch I've submitted a few days ago completely removes these and 2
other ones depend on it. It's still not in staging-testing for some reason :(

-- 
Thanks,
Giedrius
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