Subject: Re: linux-next: manual merge of the tty tree with the tty.current tree

From: Greg KH <[email-masked]>
Date: Sun, 7 Feb 2016 18:21:52 -0800

On Mon, Feb 08, 2016 at 01:16:29PM +1100, Stephen Rothwell wrote:
> Hi Greg,
> 
> Today's linux-next merge of the tty tree got a conflict in:
> 
>   drivers/tty/tty_io.c
> 
> between commit:
> 
>   e9036d066236 ("tty: Drop krefs for interrupted tty lock")
> 
> from the tty.current tree and commit:
> 
>   d6203d0c7b73 ("tty: Refactor tty_open()")
> 
> from the tty tree.
> 
> I fixed it up (I think - see below) and can carry the fix as necessary
> (no action is required).
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc drivers/tty/tty_io.c
> index a7eacef1bd22,8d26ed79bb4c..000000000000
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@@ -2004,6 -2009,69 +2009,68 @@@ static struct tty_driver *tty_lookup_dr
>   }
>   
>   /**
> +  *	tty_open_by_driver	-	open a tty device
> +  *	@device: dev_t of device to open
> +  *	@inode: inode of device file
> +  *	@filp: file pointer to tty
> +  *
> +  *	Performs the driver lookup, checks for a reopen, or otherwise
> +  *	performs the first-time tty initialization.
> +  *
> +  *	Returns the locked initialized or re-opened &tty_struct
> +  *
> +  *	Claims the global tty_mutex to serialize:
> +  *	  - concurrent first-time tty initialization
> +  *	  - concurrent tty driver removal w/ lookup
> +  *	  - concurrent tty removal from driver table
> +  */
> + static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
> + 					     struct file *filp)
> + {
> + 	struct tty_struct *tty;
> + 	struct tty_driver *driver = NULL;
> + 	int index = -1;
> + 	int retval;
> + 
> + 	mutex_lock(&tty_mutex);
> + 	driver = tty_lookup_driver(device, filp, &index);
> + 	if (IS_ERR(driver)) {
> + 		mutex_unlock(&tty_mutex);
> + 		return ERR_CAST(driver);
> + 	}
> + 
> + 	/* check whether we're reopening an existing tty */
> + 	tty = tty_driver_lookup_tty(driver, inode, index);
> + 	if (IS_ERR(tty)) {
> + 		mutex_unlock(&tty_mutex);
> + 		goto out;
> + 	}
> + 
> + 	if (tty) {
> + 		mutex_unlock(&tty_mutex);
> + 		retval = tty_lock_interruptible(tty);
> ++		tty_kref_put(tty);  /* drop kref from tty_driver_lookup_tty() */
> + 		if (retval) {
> + 			if (retval == -EINTR)
> + 				retval = -ERESTARTSYS;
> + 			tty = ERR_PTR(retval);
> + 			goto out;
> + 		}
>  -		/* safe to drop the kref from tty_driver_lookup_tty() */
>  -		tty_kref_put(tty);
> + 		retval = tty_reopen(tty);
> + 		if (retval < 0) {
> + 			tty_unlock(tty);
> + 			tty = ERR_PTR(retval);
> + 		}
> + 	} else { /* Returns with the tty_lock held for now */
> + 		tty = tty_init_dev(driver, index);
> + 		mutex_unlock(&tty_mutex);
> + 	}
> + out:
> + 	tty_driver_kref_put(driver);
> + 	return tty;
> + }
> + 
> + /**
>    *	tty_open		-	open a tty device
>    *	@inode: inode of device file
>    *	@filp: file pointer to tty

Peter warned me this was going to happen...

Peter, is the merge above correct?

thanks,

greg k-h