linux-kernel - Re: [PATCH] gigaset: turn nonsense checks into WARN

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Date:	Sat, 12 Dec 2015 19:17:19 +0100
From:	Tilman Schmidt <tilman@...p.cc>
To:	Alan Cox <alan@...ux.intel.com>, linux-kernel@...r.kernel.org
Cc:	Paul Bolle <pebolle@...cali.nl>
Subject: Re: [PATCH] gigaset: turn nonsense checks into WARN_ON

Am 09.12.2015 um 21:33 schrieb Alan Cox:
> These checks do nothing useful to protect the code from races. On the other
> hand if the old code has been masking a real bug we would like to know about
> it.
> 
> The check for tiocmset is kept because it is valid for a tty driver to have
> a NULL tiocmset method. That in itself is probably a mistake given modern
> coding practices - but needs fixing in the tty layer.
> 
> Signed-off-by: Alan Cox <alan@...ux.intel.com>

Acked-by: Tilman Schmidt <tilman@...p.cc>

(Overlooking the nettling subject line.)

> ---
>  drivers/isdn/gigaset/ser-gigaset.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c
> index d8771b5..8e21f6af 100644
> --- a/drivers/isdn/gigaset/ser-gigaset.c
> +++ b/drivers/isdn/gigaset/ser-gigaset.c
> @@ -67,8 +67,7 @@ static int write_modem(struct cardstate *cs)
>  	struct sk_buff *skb = bcs->tx_skb;
>  	int sent = -EOPNOTSUPP;
>  
> -	if (!tty || !tty->ops || !skb)
> -		return -EINVAL;
> +	WARN_ON(!tty || !tty->ops || !skb);
>  
>  	if (!skb->len) {
>  		dev_kfree_skb_any(skb);
> @@ -109,8 +108,7 @@ static int send_cb(struct cardstate *cs)
>  	unsigned long flags;
>  	int sent = 0;
>  
> -	if (!tty || !tty->ops)
> -		return -EFAULT;
> +	WARN_ON(!tty || !tty->ops);
>  
>  	cb = cs->cmdbuf;
>  	if (!cb)
> @@ -432,7 +430,9 @@ static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state,
>  	struct tty_struct *tty = cs->hw.ser->tty;
>  	unsigned int set, clear;
>  
> -	if (!tty || !tty->ops || !tty->ops->tiocmset)
> +	WARN_ON(!tty || !tty->ops);
> +	/* tiocmset is an optional tty driver method */
> +	if (!tty->ops->tiocmset)
>  		return -EINVAL;
>  	set = new_state & ~old_state;
>  	clear = old_state & ~new_state;
> 

-- 
Tilman Schmidt                              E-Mail: tilman@...p.cc
Bonn, Germany
Nous, on a des fleurs et des bougies pour nous protéger.


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