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

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Date:	Thu, 31 Mar 2016 20:49:24 -0700
From:	Greg KH <greg@...ah.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next <linux-next@...r.kernel.org>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: manual merge of the tty tree with the tty.current
 tree

On Thu, Mar 31, 2016 at 05:23:27PM -0700, Peter Hurley wrote:
> On Sun, Feb 7, 2016 at 6:21 PM, Greg KH <greg@...ah.com> wrote:
> > 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?
> 
> Greg, this merge correction did not make it into 4.6-rc1.
> 
> Was I supposed to send a separate patch for this merge change?
> Should I now?

The patch you sent should be fine, thanks.

greg k-h