linux-kernel - Re: [PATCH] staging: speakup: change semaphore to completion

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Date:   Mon, 10 Dec 2018 23:08:50 +0100
From:   Samuel Thibault <samuel.thibault@...-lyon.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     William Hubbs <w.d.hubbs@...il.com>,
        Chris Brannon <chris@...-brannons.com>,
        Kirk Reiser <kirk@...sers.ca>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        speakup@...ux-speakup.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: speakup: change semaphore to completion

Arnd Bergmann, le lun. 10 déc. 2018 22:41:50 +0100, a ecrit:
> In this driver, both function the same way, but we want to eventually
> kill off semaphores, so a completion is the better choice here.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Samuel Thibault <samuel.thibault@...-lyon.org>

> ---
>  drivers/staging/speakup/spk_ttyio.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/speakup/spk_ttyio.c b/drivers/staging/speakup/spk_ttyio.c
> index 979e3ae249c1..c92bbd05516e 100644
> --- a/drivers/staging/speakup/spk_ttyio.c
> +++ b/drivers/staging/speakup/spk_ttyio.c
> @@ -10,7 +10,7 @@
>  
>  struct spk_ldisc_data {
>  	char buf;
> -	struct semaphore sem;
> +	struct completion completion;
>  	bool buf_free;
>  };
>  
> @@ -55,7 +55,7 @@ static int spk_ttyio_ldisc_open(struct tty_struct *tty)
>  	if (!ldisc_data)
>  		return -ENOMEM;
>  
> -	sema_init(&ldisc_data->sem, 0);
> +	init_completion(&ldisc_data->completion);
>  	ldisc_data->buf_free = true;
>  	speakup_tty->disc_data = ldisc_data;
>  
> @@ -95,7 +95,7 @@ static int spk_ttyio_receive_buf2(struct tty_struct *tty,
>  
>  	ldisc_data->buf = cp[0];
>  	ldisc_data->buf_free = false;
> -	up(&ldisc_data->sem);
> +	complete(&ldisc_data->completion);
>  
>  	return 1;
>  }
> @@ -286,7 +286,8 @@ static unsigned char ttyio_in(int timeout)
>  	struct spk_ldisc_data *ldisc_data = speakup_tty->disc_data;
>  	char rv;
>  
> -	if (down_timeout(&ldisc_data->sem, usecs_to_jiffies(timeout)) == -ETIME) {
> +	if (wait_for_completion_timeout(&ldisc_data->completion,
> +					usecs_to_jiffies(timeout)) == 0) {
>  		if (timeout)
>  			pr_warn("spk_ttyio: timeout (%d)  while waiting for input\n",
>  				timeout);
> -- 
> 2.20.0
> 

-- 
Samuel
Progress (n.): The process through which the Internet has evolved from
smart people in front of dumb terminals to dumb people in front of smart
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