Hi,

On Thursday 26 June 2008, Pavel Machek wrote:

Hi!

quoted

quoted

Hmm, hitting sysrq-w produces no blocked task until I eject pcmcia
card. Backtrace there is:

Greg, I believe some traces lead to sysfs, can you help here?

ide_unregister() does not complete :-(.

        device_unregister(&hwif->gendev);
+       printk("ide_unregister: waiting for rel_comp\n");
        wait_for_completion(&hwif->gendev_rel_comp);

...that wait_for_completion never returns.

[...]

Thanks for narrowing it down to wait_for_completion() call,
it was an useful hint.

From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: [PATCH] ide: fix hwif->gendev refcounting

class->dev_release is called by device_release() iff dev->release
is not present so ide_port_class_release() is never called and the
last hwif->gendev reference is not dropped.

Fix it by removing ide_port_class_release() and get_device() call
from ide_register_port() (device_create_drvdata() takes a hwif->gendev
reference anyway).

This patch fixes hang on wait_for_completion(&hwif->gendev_rel_comp)
in ide_unregister() reported by Pavel Machek.

Cc: Pavel Machek <redacted>
Cc: "Rafael J. Wysocki" <redacted>
Cc: Greg KH <redacted>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
 drivers/ide/ide-probe.c |    2 --
 drivers/ide/ide.c       |    8 --------
 2 files changed, 10 deletions(-)

Index: b/drivers/ide/ide-probe.c
===================================================================

--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c

@@ -646,8 +646,6 @@ static int ide_register_port(ide_hwif_t 
 		goto out;
 	}
 
-	get_device(&hwif->gendev);
-
 	hwif->portdev = device_create_drvdata(ide_port_class, &hwif->gendev,
 					      MKDEV(0, 0), hwif, hwif->name);
 	if (IS_ERR(hwif->portdev)) {

Index: b/drivers/ide/ide.c
===================================================================

--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c

@@ -1094,13 +1094,6 @@ struct bus_type ide_bus_type = {
 
 EXPORT_SYMBOL_GPL(ide_bus_type);
 
-static void ide_port_class_release(struct device *portdev)
-{
-	ide_hwif_t *hwif = dev_get_drvdata(portdev);
-
-	put_device(&hwif->gendev);
-}
-
 int ide_vlb_clk;
 EXPORT_SYMBOL_GPL(ide_vlb_clk);
 

@@ -1305,7 +1298,6 @@ static int __init ide_init(void)
 		ret = PTR_ERR(ide_port_class);
 		goto out_port_class;
 	}
-	ide_port_class->dev_release = ide_port_class_release;
 
 	init_ide_data();