Re: mmotm 2009-08-06-00-30 uploaded

[Dave Young]

On Sat, Aug 08, 2009 at 06:13:53PM +0800, Dave Young wrote:
> On Sat, Aug 8, 2009 at 12:49 AM, Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > On Fri, 7 Aug 2009 21:47:00 +0800 Dave Young <hidave.darkstar@xxxxxxxxx> wrote:
> >
> >> Hi, andrew
> >>
> >> Booting with this release, init (maybe getty?) reports something like:
> >>
> >> INIT: open /dev/console failed with input/output error
> >>
> >> 2.6.31-rc5 is fine.
> >>
> >> Any hints to find the root problem?
> >
> > Not really, sorry.  Might be tty changes in linux-next?
> 
> I bisected linux-next, find following patch as a result
> 
> commit 65b8c7d9be5862ff8ac839607b444b6f6b11d2fb
> Author: Alan Cox <alan@xxxxxxxxxxxxxxx>
> Date:   Thu Aug 6 09:58:02 2009 +1000
> 
>     cyclades: use the full port_close function
> 
> But, I did not select cyclades in my .config, nor do i have the hardware. Weird.

The above result is wrong, it's a mistake.

After a whole day's testing and debugging with linux-2.6 git tree and tty patch series, I found the patch causing this issue. 
--
From: Alan Cox <alan@xxxxxxxxxxxxxxx>
Subject: tty: make the kref destructor occur asynchronously
--

If we make the tty release in a work queue, then tty_reopen might fail with -EIO. I read the sysvinit source code, it will retry 5 times, if still failed, it will warning, then no output before login.

My distribution is slackware 12.2

I tested with following debug patch.

--- linux-2.6.orig/drivers/char/tty_io.c	2009-08-11 21:29:03.000000000 +0800
+++ linux-2.6/drivers/char/tty_io.c	2009-08-11 21:40:01.000000000 +0800
@@ -1246,8 +1246,10 @@ static int tty_reopen(struct tty_struct 
 {
 	struct tty_driver *driver = tty->driver;
 
-	if (test_bit(TTY_CLOSING, &tty->flags))
+	if (test_bit(TTY_CLOSING, &tty->flags)) {
+		printk(KERN_INFO "tty_io.c: closing\n");
 		return -EIO;
+	}
 
 	if (driver->type == TTY_DRIVER_TYPE_PTY &&
 	    driver->subtype == PTY_TYPE_MASTER) {
@@ -1255,8 +1257,10 @@ static int tty_reopen(struct tty_struct 
 		 * special case for PTY masters: only one open permitted,
 		 * and the slave side open count is incremented as well.
 		 */
-		if (tty->count)
+		if (tty->count) {
+			printk(KERN_INFO "tty_io.c: open count %d\n", tty->count);
 			return -EIO;
+		}
 
 		tty->link->count++;
 	}
@@ -1705,6 +1709,7 @@ static int __tty_open(struct inode *inod
 	int index;
 	dev_t device = inode->i_rdev;
 	unsigned saved_flags = filp->f_flags;
+	static int t;
 
 	nonseekable_open(inode, filp);
 
@@ -1778,8 +1783,15 @@ got_driver:
 
 	mutex_unlock(&tty_mutex);
 	tty_driver_kref_put(driver);
-	if (IS_ERR(tty))
+	if (IS_ERR(tty)) {
+		int r = PTR_ERR(tty);
+		if (t == 5) {
+			printk(KERN_INFO "%s: %d, %d, retval: %d\n", __FILE__, __LINE__, r, retval);
+			t =0;
+		} else
+			t++;
 		return PTR_ERR(tty);
+	}
 
 	filp->private_data = tty;
 	file_move(filp, &tty->tty_files);


> 
> >
> >> Another problem:
> >>
> >> When I moving mouse or pressing key the screen will become black, then restore the normal screen.
> >
> > There have been quite a lot of X problems lately.
> >
> > Could you test the bare linux-next please?
> >
> 
> 
> 
> -- 
> Regards
> dave
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