[patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Martin Schwidefsky]

[patch 1/16] s390: klist bus_find_device & driver_find_device callback.

From: Cornelia Huck <cohuck@de.ibm.com>

Add bus_find_device() and driver_find_device() which allow a callback for each
device in the bus's resp. the driver's klist.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diffstat:
 drivers/base/bus.c     |   31 +++++++++++++++++++++++++++++++
 drivers/base/driver.c  |   34 ++++++++++++++++++++++++++++++++++
 include/linux/device.h |    7 +++++++
 3 files changed, 72 insertions(+)

diff -urpN linux-2.6/drivers/base/bus.c linux-2.6-patched/drivers/base/bus.c
--- linux-2.6/drivers/base/bus.c	2005-06-21 17:36:38.000000000 +0200
+++ linux-2.6-patched/drivers/base/bus.c	2005-06-21 17:36:45.000000000 +0200
@@ -177,6 +177,37 @@ int bus_for_each_dev(struct bus_type * b
 	return error;
 }
 
+/**
+ * bus_find_device - device iterator for locating a particular device.
+ * @bus: bus type
+ * @start: Device to begin with
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the bus_for_each_dev() function above, but it
+ * returns a pointer to a device that is 'found', as determined
+ * by the @match callback. The callback should return a bool - 0 if
+ * the device doesn't match and 1 if it does.
+ * The function will return if a device is found.
+ */
+
+struct device * bus_find_device(struct bus_type * bus, struct device * start,
+				void * data, int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device * dev;
+
+	if (!bus)
+		return NULL;
+
+	klist_iter_init_node(&bus->klist_devices, &i,
+			     (start ? &start->knode_bus : NULL));
+	while ((dev = next_device(&i)))
+		if (match(dev, data))
+			break;
+	klist_iter_exit(&i);
+	return dev;
+}
 
 
 static struct device_driver * next_driver(struct klist_iter * i)
diff -urpN linux-2.6/drivers/base/driver.c linux-2.6-patched/drivers/base/driver.c
--- linux-2.6/drivers/base/driver.c	2005-06-21 17:36:38.000000000 +0200
+++ linux-2.6-patched/drivers/base/driver.c	2005-06-21 17:36:45.000000000 +0200
@@ -56,6 +56,40 @@ EXPORT_SYMBOL_GPL(driver_for_each_device
 
 
 /**
+ * driver_find_device - device iterator for locating a particular device.
+ * @driver: The device's driver
+ * @start: Device to begin with
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the driver_for_each_device() function above, but it
+ * returns a pointer to a device that is 'found', as determined
+ * by the @match callback. The callback should return a bool - 0 if
+ * the device doesn't match and 1 if it does.
+ * The function will return if a device is found.
+ */
+
+struct device * driver_find_device(struct device_driver *drv,
+				   struct device * start, void * data,
+				   int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device * dev;
+
+	if (!drv)
+		return NULL;
+
+	klist_iter_init_node(&drv->klist_devices, &i,
+			     (start ? &start->knode_driver : NULL));
+	while ((dev = next_device(&i)))
+		if (match(dev, data))
+			break;
+	klist_iter_exit(&i);
+	return dev;
+}
+
+
+/**
  *	driver_create_file - create sysfs file for driver.
  *	@drv:	driver.
  *	@attr:	driver attribute descriptor.
diff -urpN linux-2.6/include/linux/device.h linux-2.6-patched/include/linux/device.h
--- linux-2.6/include/linux/device.h	2005-06-21 17:36:39.000000000 +0200
+++ linux-2.6-patched/include/linux/device.h	2005-06-21 17:36:45.000000000 +0200
@@ -81,6 +81,9 @@ extern struct bus_type * find_bus(char *
 int bus_for_each_dev(struct bus_type * bus, struct device * start, void * data,
 		     int (*fn)(struct device *, void *));
 
+struct device *  bus_find_device(struct bus_type * bus, struct device * start,
+				 void * data, int (*match)(struct device *, void *));
+
 int bus_for_each_drv(struct bus_type * bus, struct device_driver * start, 
 		     void * data, int (*fn)(struct device_driver *, void *));
 
@@ -143,6 +146,10 @@ extern void driver_remove_file(struct de
 extern int driver_for_each_device(struct device_driver * drv, struct device * start,
 				  void * data, int (*fn)(struct device *, void *));
 
+struct device *  driver_find_device(struct device_driver * drv,
+				    struct device * start, void * data,
+				    int (*match)(struct device *, void *));
+
 
 /*
  * device classes

Re: [patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Greg KH]

On Tue, Jun 21, 2005 at 06:22:13PM +0200, Martin Schwidefsky wrote:
> [patch 1/16] s390: klist bus_find_device & driver_find_device callback.
> 
> From: Cornelia Huck <cohuck@de.ibm.com>
> 
> Add bus_find_device() and driver_find_device() which allow a callback for each
> device in the bus's resp. the driver's klist.
> 
> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
> 
> diffstat:
>  drivers/base/bus.c     |   31 +++++++++++++++++++++++++++++++
>  drivers/base/driver.c  |   34 ++++++++++++++++++++++++++++++++++
>  include/linux/device.h |    7 +++++++
>  3 files changed, 72 insertions(+)
> 
> diff -urpN linux-2.6/drivers/base/bus.c linux-2.6-patched/drivers/base/bus.c
> --- linux-2.6/drivers/base/bus.c	2005-06-21 17:36:38.000000000 +0200
> +++ linux-2.6-patched/drivers/base/bus.c	2005-06-21 17:36:45.000000000 +0200
> @@ -177,6 +177,37 @@ int bus_for_each_dev(struct bus_type * b
>  	return error;
>  }
>  
> +/**
> + * bus_find_device - device iterator for locating a particular device.
> + * @bus: bus type
> + * @start: Device to begin with
> + * @data: Data to pass to match function
> + * @match: Callback function to check device
> + *
> + * This is similar to the bus_for_each_dev() function above, but it
> + * returns a pointer to a device that is 'found', as determined
> + * by the @match callback. The callback should return a bool - 0 if
> + * the device doesn't match and 1 if it does.
> + * The function will return if a device is found.
> + */
> +
> +struct device * bus_find_device(struct bus_type * bus, struct device * start,
> +				void * data, int (*match)(struct device *, void *))
> +{
> +	struct klist_iter i;
> +	struct device * dev;
> +
> +	if (!bus)
> +		return NULL;
> +
> +	klist_iter_init_node(&bus->klist_devices, &i,
> +			     (start ? &start->knode_bus : NULL));
> +	while ((dev = next_device(&i)))
> +		if (match(dev, data))
> +			break;
> +	klist_iter_exit(&i);
> +	return dev;
> +}

What's wrong with just using bus_for_each_dev() instead?  You have to
supply a "match" type function anyway, so the caller doesn't have an
easier time using this function instead.

You also don't increment the reference properly when you return the
pointer, so you better document that... :(

In short, I don't think this is needed at all, as it's an almost
identical copy of bus_for_each_dev().

> diff -urpN linux-2.6/drivers/base/driver.c linux-2.6-patched/drivers/base/driver.c
> --- linux-2.6/drivers/base/driver.c	2005-06-21 17:36:38.000000000 +0200
> +++ linux-2.6-patched/drivers/base/driver.c	2005-06-21 17:36:45.000000000 +0200
> @@ -56,6 +56,40 @@ EXPORT_SYMBOL_GPL(driver_for_each_device
>  
>  
>  /**
> + * driver_find_device - device iterator for locating a particular device.
> + * @driver: The device's driver
> + * @start: Device to begin with
> + * @data: Data to pass to match function
> + * @match: Callback function to check device
> + *
> + * This is similar to the driver_for_each_device() function above, but it
> + * returns a pointer to a device that is 'found', as determined
> + * by the @match callback. The callback should return a bool - 0 if
> + * the device doesn't match and 1 if it does.
> + * The function will return if a device is found.
> + */
> +
> +struct device * driver_find_device(struct device_driver *drv,
> +				   struct device * start, void * data,
> +				   int (*match)(struct device *, void *))
> +{
> +	struct klist_iter i;
> +	struct device * dev;
> +
> +	if (!drv)
> +		return NULL;
> +
> +	klist_iter_init_node(&drv->klist_devices, &i,
> +			     (start ? &start->knode_driver : NULL));
> +	while ((dev = next_device(&i)))
> +		if (match(dev, data))
> +			break;
> +	klist_iter_exit(&i);
> +	return dev;
> +}

Same comment as above, I don't think this function is necessary.

thanks,

greg k-h

Re: [patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Cornelia Huck]

Greg KH <greg@kroah.com> wrote on 22.06.2005 08:26:27:

> What's wrong with just using bus_for_each_dev() instead?  You have to
> supply a "match" type function anyway, so the caller doesn't have an
> easier time using this function instead.

Maybe it's just too early in the morning, but I don't see how I could
achive what I want to do with bus_for_each_dev(). The idea behind
bus_find_device() is to scan the bus for a device matching some
criterium and to return a pointer to it with which the caller can
continue to work. bus_for_each_dev() calls the match function for
every device until we abort, but I don't see how I can grab a reference
to a specific device for later use.

> You also don't increment the reference properly when you return the
> pointer, so you better document that... :(

You're right, this should be done in the base code and not by the
caller...

> In short, I don't think this is needed at all, as it's an almost
> identical copy of bus_for_each_dev().

It looks similar, yes, but they are for different purposes:
- bus_for_each_dev(): do something for each device (as specified
  in the callback function)
- bus_find_device(): get a reference to a specific device for later
  use (as matched in the callback function)

> Same comment as above, I don't think this function is necessary.

Same comment from me, I think I need this interface for drivers
as well.

> thanks,
> 
> greg k-h

Regards,
Cornelia

Re: [patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Greg KH]

On Wed, Jun 22, 2005 at 09:48:02AM +0200, Cornelia Huck wrote:
> Greg KH <greg@kroah.com> wrote on 22.06.2005 08:26:27:
> 
> > What's wrong with just using bus_for_each_dev() instead?  You have to
> > supply a "match" type function anyway, so the caller doesn't have an
> > easier time using this function instead.
> 
> Maybe it's just too early in the morning, but I don't see how I could
> achive what I want to do with bus_for_each_dev(). The idea behind
> bus_find_device() is to scan the bus for a device matching some
> criterium and to return a pointer to it with which the caller can
> continue to work. bus_for_each_dev() calls the match function for
> every device until we abort, but I don't see how I can grab a reference
> to a specific device for later use.

Ah, now I get it.  "later use" is the key point here.  I was thinking
you could do whatever you want within the callback.  But if you want to
do something later on with this pointer, that would be very tough.

Hm, I could use this kind of function, as I had to jump through a few
hoops when iterating over all devices on a bus, when I just wanted to
find a specific device (it involved creating a temp structure on the
stack and doing my logic in the callback function itself, for details
see
http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/driver/driver-bind.patch
for a patch that adds manual binding of drivers to devices from
userspace through sysfs.  With this function it should get even smaller.)

> > You also don't increment the reference properly when you return the
> > pointer, so you better document that... :(
> 
> You're right, this should be done in the base code and not by the
> caller...

Care to fix this up and resend it?

Sorry for the misunderstanding.

thanks,

greg k-h

Re: [patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Cornelia Huck]

On Wed, 22 Jun 2005 01:14:12 -0700
Greg KH <gregkh@suse.de> wrote:

> Care to fix this up and resend it?

Yes, patches are on the way that supersede patches 1/16 and 2/16 from
Martin's batch. The other patches are not affected by the change.
> 
> Sorry for the misunderstanding.

I should have written a better description :)

> 
> thanks,
> 
> greg k-h

Regards,
Cornelia

[patch 1/2] s390: klist bus_find_device & driver_find_device callback.

[Cornelia Huck]

[patch 1/2] s390: klist bus_find_device & driver_find_device callback.

Add bus_find_device() and driver_find_device() which allow searching for a
device in the bus's resp. the driver's klist and obtain a reference on it.

This version now increases the reference count for the device to be returned.
Also, the interface has been exported to GPL modules and the comments have
been improved.

Signed-off-by: Cornelia Huck <cohuck@de.ibm.com>

 drivers/base/bus.c     |   33 +++++++++++++++++++++++++++++++++
 drivers/base/driver.c  |   35 +++++++++++++++++++++++++++++++++++
 include/linux/device.h |    7 +++++++
 3 files changed, 75 insertions(+), 0 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -177,6 +177,38 @@ int bus_for_each_dev(struct bus_type * b
 	return error;
 }
 
+/**
+ * bus_find_device - device iterator for locating a particular device.
+ * @bus: bus type
+ * @start: Device to begin with
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the bus_for_each_dev() function above, but it
+ * returns a reference to a device that is 'found' for later use, as determined
+ * by the @match callback. The callback should return a bool - 0 if
+ * the device doesn't match and 1 if it does.
+ * The function will return if a device is found.
+ */
+
+struct device * bus_find_device(struct bus_type * bus,
+				struct device * start, void * data,
+				int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device * dev;
+
+	if (!bus)
+		return NULL;
+
+	klist_iter_init_node(&bus->klist_devices, &i,
+			     (start ? &start->knode_bus : NULL));
+	while ((dev = next_device(&i)))
+		if (match(dev, data) && get_device(dev))
+			break;
+	klist_iter_exit(&i);
+	return dev;
+}
 
 
 static struct device_driver * next_driver(struct klist_iter * i)
@@ -558,6 +590,7 @@ int __init buses_init(void)
 
 
 EXPORT_SYMBOL_GPL(bus_for_each_dev);
+EXPORT_SYMBOL_GPL(bus_find_device);
 EXPORT_SYMBOL_GPL(bus_for_each_drv);
 
 EXPORT_SYMBOL_GPL(bus_add_device);
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -56,6 +56,41 @@ EXPORT_SYMBOL_GPL(driver_for_each_device
 
 
 /**
+ * driver_find_device - device iterator for locating a particular device.
+ * @driver: The device's driver
+ * @start: Device to begin with
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the driver_for_each_device() function above, but it
+ * returns a reference to a device that is 'found' for later use, as determined
+ * by the @match callback. The callback should return a bool - 0 if
+ * the device doesn't match and 1 if it does.
+ * The function will return if a device is found.
+ */
+
+struct device * driver_find_device(struct device_driver *drv,
+				   struct device * start, void * data,
+				   int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device * dev;
+
+	if (!drv)
+		return NULL;
+
+	klist_iter_init_node(&drv->klist_devices, &i,
+			     (start ? &start->knode_driver : NULL));
+	while ((dev = next_device(&i)))
+		if (match(dev, data) && get_device(dev))
+			break;
+	klist_iter_exit(&i);
+	return dev;
+}
+
+EXPORT_SYMBOL_GPL(driver_find_device);
+
+/**
  *	driver_create_file - create sysfs file for driver.
  *	@drv:	driver.
  *	@attr:	driver attribute descriptor.
diff --git a/include/linux/device.h b/include/linux/device.h
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -81,6 +81,9 @@ extern struct bus_type * find_bus(char *
 int bus_for_each_dev(struct bus_type * bus, struct device * start, void * data,
 		     int (*fn)(struct device *, void *));
 
+struct device *  bus_find_device(struct bus_type * bus, struct device * start,
+				 void * data, int (*match)(struct device *, void *));
+
 int bus_for_each_drv(struct bus_type * bus, struct device_driver * start, 
 		     void * data, int (*fn)(struct device_driver *, void *));
 
@@ -143,6 +146,10 @@ extern void driver_remove_file(struct de
 extern int driver_for_each_device(struct device_driver * drv, struct device * start,
 				  void * data, int (*fn)(struct device *, void *));
 
+struct device *  driver_find_device(struct device_driver * drv,
+				    struct device * start, void * data,
+				    int (*match)(struct device *, void *));
+
 
 /*
  * device classes

[patch 2/2] s390: use klist in cio.

[Cornelia Huck]

[patch 2/2] s390: use klist in cio.

Convert the common I/O layer to use the klist interfaces.

This patch has been adapted from the previous version to the changed interface
semantics. Also, gcc 4.0 compile warnings have been removed.

Signed-off-by: Cornelia Huck <cohuck@de.ibm.com>

 drivers/s390/cio/ccwgroup.c |   30 +++++----------
 drivers/s390/cio/css.c      |   34 +++++++----------
 drivers/s390/cio/device.c   |   84 ++++++++++++++++++++++---------------------
 3 files changed, 66 insertions(+), 82 deletions(-)

diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -403,34 +403,22 @@ ccwgroup_driver_register (struct ccwgrou
 	return driver_register(&cdriver->driver);
 }
 
-static inline struct device *
-__get_next_ccwgroup_device(struct device_driver *drv)
+static int
+__ccwgroup_driver_unregister_device(struct device *dev, void *data)
 {
-	struct device *dev, *d;
-
-	down_read(&drv->bus->subsys.rwsem);
-	dev = NULL;
-	list_for_each_entry(d, &drv->devices, driver_list) {
-		dev = get_device(d);
-		if (dev)
-			break;
-	}
-	up_read(&drv->bus->subsys.rwsem);
-	return dev;
+	__ccwgroup_remove_symlinks(to_ccwgroupdev(dev));
+	device_unregister(dev);
+	put_device(dev);
+	return 0;
 }
 
 void
 ccwgroup_driver_unregister (struct ccwgroup_driver *cdriver)
 {
-	struct device *dev;
-
 	/* We don't want ccwgroup devices to live longer than their driver. */
 	get_driver(&cdriver->driver);
-	while ((dev = __get_next_ccwgroup_device(&cdriver->driver))) {
-		__ccwgroup_remove_symlinks(to_ccwgroupdev(dev));
-		device_unregister(dev);
-		put_device(dev);
-	};
+	driver_for_each_device(&cdriver->driver, NULL, NULL,
+			       __ccwgroup_driver_unregister_device);
 	put_driver(&cdriver->driver);
 	driver_unregister(&cdriver->driver);
 }
@@ -449,7 +437,7 @@ __ccwgroup_get_gdev_by_cdev(struct ccw_d
 	if (cdev->dev.driver_data) {
 		gdev = (struct ccwgroup_device *)cdev->dev.driver_data;
 		if (get_device(&gdev->dev)) {
-			if (!list_empty(&gdev->dev.node))
+			if (klist_node_attached(&gdev->dev.knode_bus))
 				return gdev;
 			put_device(&gdev->dev);
 		}
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -128,34 +128,28 @@ css_probe_device(int irq)
 	return ret;
 }
 
+static int
+check_subchannel(struct device * dev, void * data)
+{
+	struct subchannel *sch;
+	int irq = (unsigned long)data;
+
+	sch = to_subchannel(dev);
+	return (sch->irq == irq);
+}
+
 struct subchannel *
 get_subchannel_by_schid(int irq)
 {
-	struct subchannel *sch;
-	struct list_head *entry;
 	struct device *dev;
 
-	if (!get_bus(&css_bus_type))
-		return NULL;
-	down_read(&css_bus_type.subsys.rwsem);
-	sch = NULL;
-	list_for_each(entry, &css_bus_type.devices.list) {
-		dev = get_device(container_of(entry,
-					      struct device, bus_list));
-		if (!dev)
-			continue;
-		sch = to_subchannel(dev);
-		if (sch->irq == irq)
-			break;
-		put_device(dev);
-		sch = NULL;
-	}
-	up_read(&css_bus_type.subsys.rwsem);
-	put_bus(&css_bus_type);
+	dev = bus_find_device(&css_bus_type, NULL,
+			      (void *)(unsigned long)irq, check_subchannel);
 
-	return sch;
+	return dev ? to_subchannel(dev) : NULL;
 }
 
+
 static inline int
 css_get_subchannel_status(struct subchannel *sch, int schid)
 {
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -514,36 +514,39 @@ ccw_device_register(struct ccw_device *c
 	return ret;
 }
 
+struct match_data {
+	unsigned int  devno;
+	struct ccw_device * sibling;
+};
+
+static int
+match_devno(struct device * dev, void * data)
+{
+	struct match_data * d = (struct match_data *)data;
+	struct ccw_device * cdev;
+
+	cdev = to_ccwdev(dev);
+	if ((cdev->private->state == DEV_STATE_DISCONNECTED) &&
+	    (cdev->private->devno == d->devno) &&
+	    (cdev != d->sibling)) {
+		cdev->private->state = DEV_STATE_NOT_OPER;
+		return 1;
+	}
+	return 0;
+}
+
 static struct ccw_device *
 get_disc_ccwdev_by_devno(unsigned int devno, struct ccw_device *sibling)
 {
-	struct ccw_device *cdev;
-	struct list_head *entry;
 	struct device *dev;
+	struct match_data data = {
+		.devno  = devno,
+		.sibling = sibling,
+	};
 
-	if (!get_bus(&ccw_bus_type))
-		return NULL;
-	down_read(&ccw_bus_type.subsys.rwsem);
-	cdev = NULL;
-	list_for_each(entry, &ccw_bus_type.devices.list) {
-		dev = get_device(container_of(entry,
-					      struct device, bus_list));
-		if (!dev)
-			continue;
-		cdev = to_ccwdev(dev);
-		if ((cdev->private->state == DEV_STATE_DISCONNECTED) &&
-		    (cdev->private->devno == devno) &&
-		    (cdev != sibling)) {
-			cdev->private->state = DEV_STATE_NOT_OPER;
-			break;
-		}
-		put_device(dev);
-		cdev = NULL;
-	}
-	up_read(&ccw_bus_type.subsys.rwsem);
-	put_bus(&ccw_bus_type);
+	dev = bus_find_device(&css_bus_type, NULL, &data, match_devno);
 
-	return cdev;
+	return dev ? to_ccwdev(dev) : NULL;
 }
 
 static void
@@ -647,7 +650,7 @@ io_subchannel_register(void *data)
 	cdev = (struct ccw_device *) data;
 	sch = to_subchannel(cdev->dev.parent);
 
-	if (!list_empty(&sch->dev.children)) {
+	if (klist_node_attached(&cdev->dev.knode_parent)) {
 		bus_rescan_devices(&ccw_bus_type);
 		goto out;
 	}
@@ -1019,30 +1022,29 @@ ccw_device_probe_console(void)
 /*
  * get ccw_device matching the busid, but only if owned by cdrv
  */
+static int
+__ccwdev_check_busid(struct device *dev, void *id)
+{
+	char *bus_id;
+
+	bus_id = (char *)id;
+
+	return (strncmp(bus_id, dev->bus_id, BUS_ID_SIZE) == 0);
+}
+	
+
 struct ccw_device *
 get_ccwdev_by_busid(struct ccw_driver *cdrv, const char *bus_id)
 {
-	struct device *d, *dev;
+	struct device *dev;
 	struct device_driver *drv;
 
 	drv = get_driver(&cdrv->driver);
 	if (!drv)
-		return 0;
-
-	down_read(&drv->bus->subsys.rwsem);
-
-	dev = NULL;
-	list_for_each_entry(d, &drv->devices, driver_list) {
-		dev = get_device(d);
+		return NULL;
 
-		if (dev && !strncmp(bus_id, dev->bus_id, BUS_ID_SIZE))
-			break;
-		else if (dev) {
-			put_device(dev);
-			dev = NULL;
-		}
-	}
-	up_read(&drv->bus->subsys.rwsem);
+	dev = driver_find_device(drv, NULL, (void *)bus_id,
+				 __ccwdev_check_busid);
 	put_driver(drv);
 
 	return dev ? to_ccwdev(dev) : 0;

Re: [patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Christoph Hellwig]

> +struct device * bus_find_device(struct bus_type * bus, struct device * start,
> +				void * data, int (*match)(struct device *, void *))
> +{
> +	struct klist_iter i;
> +	struct device * dev;
> +
> +	if (!bus)
> +		return NULL;
> +
> +	klist_iter_init_node(&bus->klist_devices, &i,
> +			     (start ? &start->knode_bus : NULL));
> +	while ((dev = next_device(&i)))
> +		if (match(dev, data))
> +			break;
> +	klist_iter_exit(&i);
> +	return dev;

does the klist magic somehow grab a reference for you?

Re: [patch 1/16] s390: klist bus_find_device & driver_find_device callback.

[Greg KH]

On Wed, Jun 22, 2005 at 09:11:02AM +0100, Christoph Hellwig wrote:
> > +struct device * bus_find_device(struct bus_type * bus, struct device * start,
> > +				void * data, int (*match)(struct device *, void *))
> > +{
> > +	struct klist_iter i;
> > +	struct device * dev;
> > +
> > +	if (!bus)
> > +		return NULL;
> > +
> > +	klist_iter_init_node(&bus->klist_devices, &i,
> > +			     (start ? &start->knode_bus : NULL));
> > +	while ((dev = next_device(&i)))
> > +		if (match(dev, data))
> > +			break;
> > +	klist_iter_exit(&i);
> > +	return dev;
> 
> does the klist magic somehow grab a reference for you?

No, see my previous comment about the need for this to be fixed for
these two functions.

thanks,

greg k-h