linux-kernel - Re: [PATCH 1/2] staging: dgnc: remove dead code in dgnc_tty

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Date:	Mon, 6 Apr 2015 02:28:43 +0300 (EEST)
From:	Giedrius Statkevičius 
	<giedrius.statkevicius@...il.com>
To:	Giedrius Statkevicius <giedrius.statkevicius@...il.com>
cc:	lidza.louina@...il.com, markh@...pro.net,
	gregkh@...uxfoundation.org, driverdev-devel@...uxdriverproject.org,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] staging: dgnc: remove dead code in
 dgnc_tty_write()

Forgot to put "v2" in the title. Should I resend? Sorry for the confusion. Still
making some patch submitting mistakes from time to time. :(

On Mon, 6 Apr 2015, Giedrius Statkevicius wrote:

> Remove the dead code protected by in_user in dgnc_tty_write() because it is set
> to 0 and never changed to 1 thus the code in ifs never gets executed.
> 
> Signed-off-by: Giedrius Statkevičius <giedrius.statkevicius@...il.com>
> ---
> v2: Just remove the dead code protected by in_user and join the first and third
> patches.
> 
>  drivers/staging/dgnc/dgnc_tty.c | 45 +----------------------------------------
>  1 file changed, 1 insertion(+), 44 deletions(-)
> 
> diff --git a/drivers/staging/dgnc/dgnc_tty.c b/drivers/staging/dgnc/dgnc_tty.c
> index ce4187f..cf2eb21 100644
> --- a/drivers/staging/dgnc/dgnc_tty.c
> +++ b/drivers/staging/dgnc/dgnc_tty.c
> @@ -42,16 +42,11 @@
>  #include "dgnc_sysfs.h"
>  #include "dgnc_utils.h"
>  
> -#define init_MUTEX(sem)	 sema_init(sem, 1)
> -#define DECLARE_MUTEX(name)     \
> -	struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
> -
>  /*
>   * internal variables
>   */
>  static struct dgnc_board	*dgnc_BoardsByMajor[256];
>  static unsigned char		*dgnc_TmpWriteBuf;
> -static DECLARE_MUTEX(dgnc_TmpWriteSem);
>  
>  /*
>   * Default transparent print information.
> @@ -1705,7 +1700,6 @@ static int dgnc_tty_write(struct tty_struct *tty,
>  	ushort tail;
>  	ushort tmask;
>  	uint remain;
> -	int from_user = 0;
>  
>  	if (tty == NULL || dgnc_TmpWriteBuf == NULL)
>  		return 0;
> @@ -1785,38 +1779,6 @@ static int dgnc_tty_write(struct tty_struct *tty,
>  	if (count <= 0)
>  		goto exit_retry;
>  
> -	if (from_user) {
> -
> -		count = min(count, WRITEBUFLEN);
> -
> -		spin_unlock_irqrestore(&ch->ch_lock, flags);
> -
> -		/*
> -		 * If data is coming from user space, copy it into a temporary
> -		 * buffer so we don't get swapped out while doing the copy to
> -		 * the board.
> -		 */
> -		/* we're allowed to block if it's from_user */
> -		if (down_interruptible(&dgnc_TmpWriteSem))
> -			return -EINTR;
> -
> -		/*
> -		 * copy_from_user() returns the number
> -		 * of bytes that could *NOT* be copied.
> -		 */
> -		count -= copy_from_user(dgnc_TmpWriteBuf, (const unsigned char __user *) buf, count);
> -
> -		if (!count) {
> -			up(&dgnc_TmpWriteSem);
> -			return -EFAULT;
> -		}
> -
> -		spin_lock_irqsave(&ch->ch_lock, flags);
> -
> -		buf = dgnc_TmpWriteBuf;
> -
> -	}
> -
>  	n = count;
>  
>  	/*
> @@ -1853,12 +1815,7 @@ static int dgnc_tty_write(struct tty_struct *tty,
>  		ch->ch_cpstime += (HZ * count) / ch->ch_digi.digi_maxcps;
>  	}
>  
> -	if (from_user) {
> -		spin_unlock_irqrestore(&ch->ch_lock, flags);
> -		up(&dgnc_TmpWriteSem);
> -	} else {
> -		spin_unlock_irqrestore(&ch->ch_lock, flags);
> -	}
> +	spin_unlock_irqrestore(&ch->ch_lock, flags);
>  
>  	if (count) {
>  		/*
> -- 
> 2.3.5
> 
> 

Su pagarba / Regards,
Giedrius