linux-kernel - Re: [PATCH] use mutex instead of semaphore in RocketPort driver v2

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Date:	Wed, 25 Apr 2007 15:58:50 +0200
From:	Jiri Slaby <jirislaby@...il.com>
To:	Matthias Kaehlcke <matthias.kaehlcke@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] use mutex instead of semaphore in RocketPort driver v2

Matthias Kaehlcke napsal(a):
> the RocketPort driver uses a semaphore as mutex. use the mutex API
> instead of the (binary) semaphore
> 
> Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@...il.com>
> 
> --
> 
> diff --git a/drivers/char/rocket.c b/drivers/char/rocket.c
> index 76357c8..7d23790 100644
> --- a/drivers/char/rocket.c
> +++ b/drivers/char/rocket.c
> @@ -702,7 +702,7 @@ static void init_r_port(int board, int aiop, int chan, struct pci_dev *pci_dev)
>  		}
>  	}
>  	spin_lock_init(&info->slock);
> -	sema_init(&info->write_sem, 1);
> +	mutex_init(&info->write_mtx);
>  	rp_table[line] = info;
>  	if (pci_dev)
>  		tty_register_device(rocket_driver, line, &pci_dev->dev);
> @@ -1662,7 +1662,7 @@ static void rp_put_char(struct tty_struct *tty, unsigned char ch)
>  		return;
>  
>  	/*  Grab the port write semaphore, locking out other processes that try to write to this port */
> -	down(&info->write_sem);
> +	mutex_lock(&info->write_mtx);
>  
>  #ifdef ROCKET_DEBUG_WRITE
>  	printk(KERN_INFO "rp_put_char %c...", ch);
> @@ -1684,7 +1684,7 @@ static void rp_put_char(struct tty_struct *tty, unsigned char ch)
>  		info->xmit_fifo_room--;
>  	}
>  	spin_unlock_irqrestore(&info->slock, flags);
> -	up(&info->write_sem);
> +	mutex_unlock(&info->write_mtx);
>  }
>  
>  /*
> @@ -1706,7 +1706,8 @@ static int rp_write(struct tty_struct *tty,
>  	if (count <= 0 || rocket_paranoia_check(info, "rp_write"))
>  		return 0;
>  
> -	down_interruptible(&info->write_sem);
> +	if(mutex_lock_interruptible(&info->write_mtx))
          ^
and put a space here "if (".

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
 B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E
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