Patchwork ide: ide_port_wait_ready() fix

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Submitter Bartlomiej Zolnierkiewicz
Date Oct. 11, 2011, 5:13 p.m.
Message ID <201110111913.18492.bzolnier@gmail.com>
Download mbox | patch
Permalink /patch/119021/
State Changes Requested
Delegated to: David Miller
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Comments

Bartlomiej Zolnierkiewicz - Oct. 11, 2011, 5:13 p.m.
From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: [PATCH] ide: ide_port_wait_ready() fix

Fix for commit a20b2a4 ("ide: skip probe if there are no devices on
the port (v2)").  We must check for slave device before failing.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
 drivers/ide/ide-probe.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

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David Miller - Oct. 11, 2011, 7:17 p.m.
From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date: Tue, 11 Oct 2011 19:13:18 +0200

> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> Subject: [PATCH] ide: ide_port_wait_ready() fix
> 
> Fix for commit a20b2a4 ("ide: skip probe if there are no devices on
> the port (v2)").  We must check for slave device before failing.
> 
> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

This will mishandle the case where there is no slave in the device
list.
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Bartlomiej Zolnierkiewicz - Oct. 12, 2011, 2:59 p.m.
David Miller wrote:

> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> Date: Tue, 11 Oct 2011 19:13:18 +0200
> 
> > From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> > Subject: [PATCH] ide: ide_port_wait_ready() fix
> > 
> > Fix for commit a20b2a4 ("ide: skip probe if there are no devices on
> > the port (v2)").  We must check for slave device before failing.
> > 
> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> 
> This will mishandle the case where there is no slave in the device
> list.

I don't see it:

@ -598,7 +598,7 @@ static int ide_port_wait_ready(ide_hwif_
 {
 	const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 	ide_drive_t *drive;
-	int i, rc;
+	int i, rc, prev_rc = 0;
 
 	printk(KERN_DEBUG "Probing IDE interface %s...\n", hwif->name);
 
@@ -623,8 +623,10 @@ static int ide_port_wait_ready(ide_hwif_
 			tp_ops->write_devctl(hwif, ATA_DEVCTL_OBS);
 			mdelay(2);
 			rc = ide_wait_not_busy(hwif, 35000);
-			if (rc)
+			if (prev_rc && rc)
 				goto out;
+			prev_rc = rc;
+			rc = 0;
 		} else
 			printk(KERN_DEBUG "%s: ide_wait_not_busy() skipped\n",
 					  drive->name);

If there is no slave device but there is a master device the code falls-through
and returns a success.

The patch fixes regression introduced in commit a20b2a4 as some esoteric
setups return ide_wait_not_busy() -ENODEV error on master device while there
is slave device present in the system.
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David Miller - Oct. 12, 2011, 7:03 p.m.
From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date: Wed, 12 Oct 2011 16:59:55 +0200

> David Miller wrote:
> 
>> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> Date: Tue, 11 Oct 2011 19:13:18 +0200
>> 
>> > From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> > Subject: [PATCH] ide: ide_port_wait_ready() fix
>> > 
>> > Fix for commit a20b2a4 ("ide: skip probe if there are no devices on
>> > the port (v2)").  We must check for slave device before failing.
>> > 
>> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> 
>> This will mishandle the case where there is no slave in the device
>> list.
> 
> I don't see it:
> 
> @ -598,7 +598,7 @@ static int ide_port_wait_ready(ide_hwif_
>  {
>  	const struct ide_tp_ops *tp_ops = hwif->tp_ops;
>  	ide_drive_t *drive;
> -	int i, rc;
> +	int i, rc, prev_rc = 0;
>  
>  	printk(KERN_DEBUG "Probing IDE interface %s...\n", hwif->name);
>  
> @@ -623,8 +623,10 @@ static int ide_port_wait_ready(ide_hwif_
>  			tp_ops->write_devctl(hwif, ATA_DEVCTL_OBS);
>  			mdelay(2);
>  			rc = ide_wait_not_busy(hwif, 35000);
> -			if (rc)
> +			if (prev_rc && rc)
>  				goto out;
> +			prev_rc = rc;
> +			rc = 0;
>  		} else
>  			printk(KERN_DEBUG "%s: ide_wait_not_busy() skipped\n",
>  					  drive->name);
> 
> If there is no slave device but there is a master device the code falls-through
> and returns a success.

That's not what we want, if there is only a master device and no slave device
in the list this loop is iterating over we want to return the error code
in "rc", not zero.
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Bartlomiej Zolnierkiewicz - Oct. 13, 2011, 10:41 a.m.
David Miller wrote:

> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> Date: Wed, 12 Oct 2011 16:59:55 +0200
> 
> > David Miller wrote:
> > 
> >> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> >> Date: Tue, 11 Oct 2011 19:13:18 +0200
> >> 
> >> > From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> >> > Subject: [PATCH] ide: ide_port_wait_ready() fix
> >> > 
> >> > Fix for commit a20b2a4 ("ide: skip probe if there are no devices on
> >> > the port (v2)").  We must check for slave device before failing.
> >> > 
> >> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> >> 
> >> This will mishandle the case where there is no slave in the device
> >> list.
> > 
> > I don't see it:
> > 
> > @ -598,7 +598,7 @@ static int ide_port_wait_ready(ide_hwif_
> >  {
> >  	const struct ide_tp_ops *tp_ops = hwif->tp_ops;
> >  	ide_drive_t *drive;
> > -	int i, rc;
> > +	int i, rc, prev_rc = 0;
> >  
> >  	printk(KERN_DEBUG "Probing IDE interface %s...\n", hwif->name);
> >  
> > @@ -623,8 +623,10 @@ static int ide_port_wait_ready(ide_hwif_
> >  			tp_ops->write_devctl(hwif, ATA_DEVCTL_OBS);
> >  			mdelay(2);
> >  			rc = ide_wait_not_busy(hwif, 35000);
> > -			if (rc)
> > +			if (prev_rc && rc)
> >  				goto out;
> > +			prev_rc = rc;
> > +			rc = 0;
> >  		} else
> >  			printk(KERN_DEBUG "%s: ide_wait_not_busy() skipped\n",
> >  					  drive->name);
> > 
> > If there is no slave device but there is a master device the code falls-through
> > and returns a success.
> 
> That's not what we want, if there is only a master device and no slave device
> in the list this loop is iterating over we want to return the error code
> in "rc", not zero.

No, we want to return zero (success) since at least once device was found
(otherwise we fail probe on some esoteric setups returning -ENODEV from
ide_wait_not_busy() for master device).

This is how this function worked before commit a20b2a4 if you want something
else okay but it needs to work with aforementioned setups.
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David Miller - Oct. 13, 2011, 5:25 p.m.
From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date: Thu, 13 Oct 2011 12:41:04 +0200

> David Miller wrote:
> 
>> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> Date: Wed, 12 Oct 2011 16:59:55 +0200
>> 
>> > David Miller wrote:
>> > 
>> >> From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> >> Date: Tue, 11 Oct 2011 19:13:18 +0200
>> >> 
>> >> > From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> >> > Subject: [PATCH] ide: ide_port_wait_ready() fix
>> >> > 
>> >> > Fix for commit a20b2a4 ("ide: skip probe if there are no devices on
>> >> > the port (v2)").  We must check for slave device before failing.
>> >> > 
>> >> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>> >> 
>> >> This will mishandle the case where there is no slave in the device
>> >> list.
>> > 
>> > I don't see it:
>> > 
>> > @ -598,7 +598,7 @@ static int ide_port_wait_ready(ide_hwif_
>> >  {
>> >  	const struct ide_tp_ops *tp_ops = hwif->tp_ops;
>> >  	ide_drive_t *drive;
>> > -	int i, rc;
>> > +	int i, rc, prev_rc = 0;
>> >  
>> >  	printk(KERN_DEBUG "Probing IDE interface %s...\n", hwif->name);
>> >  
>> > @@ -623,8 +623,10 @@ static int ide_port_wait_ready(ide_hwif_
>> >  			tp_ops->write_devctl(hwif, ATA_DEVCTL_OBS);
>> >  			mdelay(2);
>> >  			rc = ide_wait_not_busy(hwif, 35000);
>> > -			if (rc)
>> > +			if (prev_rc && rc)
>> >  				goto out;
>> > +			prev_rc = rc;
>> > +			rc = 0;
>> >  		} else
>> >  			printk(KERN_DEBUG "%s: ide_wait_not_busy() skipped\n",
>> >  					  drive->name);
>> > 
>> > If there is no slave device but there is a master device the code falls-through
>> > and returns a success.
>> 
>> That's not what we want, if there is only a master device and no slave device
>> in the list this loop is iterating over we want to return the error code
>> in "rc", not zero.
> 
> No, we want to return zero (success) since at least once device was found
> (otherwise we fail probe on some esoteric setups returning -ENODEV from
> ide_wait_not_busy() for master device).
> 
> This is how this function worked before commit a20b2a4 if you want something
> else okay but it needs to work with aforementioned setups.

You unconditionally assign "prev_rc = rc" and set "rc = 0" so if we only run
the loop once, we return zero.

And we do this even if that one device gave a non-zero return value.

That's not what we want.
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Patch

Index: b/drivers/ide/ide-probe.c
===================================================================
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -598,7 +598,7 @@  static int ide_port_wait_ready(ide_hwif_
 {
 	const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 	ide_drive_t *drive;
-	int i, rc;
+	int i, rc, prev_rc = 0;
 
 	printk(KERN_DEBUG "Probing IDE interface %s...\n", hwif->name);
 
@@ -623,8 +623,10 @@  static int ide_port_wait_ready(ide_hwif_
 			tp_ops->write_devctl(hwif, ATA_DEVCTL_OBS);
 			mdelay(2);
 			rc = ide_wait_not_busy(hwif, 35000);
-			if (rc)
+			if (prev_rc && rc)
 				goto out;
+			prev_rc = rc;
+			rc = 0;
 		} else
 			printk(KERN_DEBUG "%s: ide_wait_not_busy() skipped\n",
 					  drive->name);