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kobject: convert hvcs to use kref, not kobject
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hvcs is using a kobject only for reference counting, nothing else.  So
switch it to use a kref instead, which is all that is needed, and is
much smaller.

Cc: Anton Blanchard <anton@au.ibm.com>
Cc: Paul Mackerras <paulus@au.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ryan S. Arnold <rsa@us.ibm.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Greg Kroah-Hartman committed Jan 25, 2008
1 parent 12b20de commit f7eb12c
Showing 1 changed file with 25 additions and 53 deletions.
78 changes: 25 additions & 53 deletions drivers/char/hvcs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,11 +57,7 @@
* rescanning partner information upon a user's request.
*
* Each vty-server, prior to being exposed to this driver is reference counted
* using the 2.6 Linux kernel kobject construct. This kobject is also used by
* the vio bus to provide a vio device sysfs entry that this driver attaches
* device specific attributes to, including partner information. The vio bus
* framework also provides a sysfs entry for each vio driver. The hvcs driver
* provides driver attributes in this entry.
* using the 2.6 Linux kernel kref construct.
*
* For direction on installation and usage of this driver please reference
* Documentation/powerpc/hvcs.txt.
Expand All @@ -71,7 +67,7 @@
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/kref.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/major.h>
Expand Down Expand Up @@ -293,12 +289,12 @@ struct hvcs_struct {
int chars_in_buffer;

/*
* Any variable below the kobject is valid before a tty is connected and
* Any variable below the kref is valid before a tty is connected and
* stays valid after the tty is disconnected. These shouldn't be
* whacked until the koject refcount reaches zero though some entries
* may be changed via sysfs initiatives.
*/
struct kobject kobj; /* ref count & hvcs_struct lifetime */
struct kref kref; /* ref count & hvcs_struct lifetime */
int connected; /* is the vty-server currently connected to a vty? */
uint32_t p_unit_address; /* partner unit address */
uint32_t p_partition_ID; /* partner partition ID */
Expand All @@ -307,8 +303,8 @@ struct hvcs_struct {
struct vio_dev *vdev;
};

/* Required to back map a kobject to its containing object */
#define from_kobj(kobj) container_of(kobj, struct hvcs_struct, kobj)
/* Required to back map a kref to its containing object */
#define from_kref(k) container_of(k, struct hvcs_struct, kref)

static struct list_head hvcs_structs = LIST_HEAD_INIT(hvcs_structs);
static DEFINE_SPINLOCK(hvcs_structs_lock);
Expand All @@ -334,7 +330,6 @@ static void hvcs_partner_free(struct hvcs_struct *hvcsd);
static int hvcs_enable_device(struct hvcs_struct *hvcsd,
uint32_t unit_address, unsigned int irq, struct vio_dev *dev);

static void destroy_hvcs_struct(struct kobject *kobj);
static int hvcs_open(struct tty_struct *tty, struct file *filp);
static void hvcs_close(struct tty_struct *tty, struct file *filp);
static void hvcs_hangup(struct tty_struct * tty);
Expand Down Expand Up @@ -703,10 +698,10 @@ static void hvcs_return_index(int index)
hvcs_index_list[index] = -1;
}

/* callback when the kboject ref count reaches zero */
static void destroy_hvcs_struct(struct kobject *kobj)
/* callback when the kref ref count reaches zero */
static void destroy_hvcs_struct(struct kref *kref)
{
struct hvcs_struct *hvcsd = from_kobj(kobj);
struct hvcs_struct *hvcsd = from_kref(kref);
struct vio_dev *vdev;
unsigned long flags;

Expand Down Expand Up @@ -743,10 +738,6 @@ static void destroy_hvcs_struct(struct kobject *kobj)
kfree(hvcsd);
}

static struct kobj_type hvcs_kobj_type = {
.release = destroy_hvcs_struct,
};

static int hvcs_get_index(void)
{
int i;
Expand Down Expand Up @@ -791,9 +782,7 @@ static int __devinit hvcs_probe(

spin_lock_init(&hvcsd->lock);
/* Automatically incs the refcount the first time */
kobject_init(&hvcsd->kobj);
/* Set up the callback for terminating the hvcs_struct's life */
hvcsd->kobj.ktype = &hvcs_kobj_type;
kref_init(&hvcsd->kref);

hvcsd->vdev = dev;
dev->dev.driver_data = hvcsd;
Expand Down Expand Up @@ -844,7 +833,6 @@ static int __devexit hvcs_remove(struct vio_dev *dev)
{
struct hvcs_struct *hvcsd = dev->dev.driver_data;
unsigned long flags;
struct kobject *kobjp;
struct tty_struct *tty;

if (!hvcsd)
Expand All @@ -856,15 +844,13 @@ static int __devexit hvcs_remove(struct vio_dev *dev)

tty = hvcsd->tty;

kobjp = &hvcsd->kobj;

spin_unlock_irqrestore(&hvcsd->lock, flags);

/*
* Let the last holder of this object cause it to be removed, which
* would probably be tty_hangup below.
*/
kobject_put (kobjp);
kref_put(&hvcsd->kref, destroy_hvcs_struct);

/*
* The hangup is a scheduled function which will auto chain call
Expand Down Expand Up @@ -1086,7 +1072,7 @@ static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
}

/*
* This always increments the kobject ref count if the call is successful.
* This always increments the kref ref count if the call is successful.
* Please remember to dec when you are done with the instance.
*
* NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
Expand All @@ -1103,7 +1089,7 @@ static struct hvcs_struct *hvcs_get_by_index(int index)
list_for_each_entry(hvcsd, &hvcs_structs, next) {
spin_lock_irqsave(&hvcsd->lock, flags);
if (hvcsd->index == index) {
kobject_get(&hvcsd->kobj);
kref_get(&hvcsd->kref);
spin_unlock_irqrestore(&hvcsd->lock, flags);
spin_unlock(&hvcs_structs_lock);
return hvcsd;
Expand All @@ -1129,14 +1115,13 @@ static int hvcs_open(struct tty_struct *tty, struct file *filp)
unsigned int irq;
struct vio_dev *vdev;
unsigned long unit_address;
struct kobject *kobjp;

if (tty->driver_data)
goto fast_open;

/*
* Is there a vty-server that shares the same index?
* This function increments the kobject index.
* This function increments the kref index.
*/
if (!(hvcsd = hvcs_get_by_index(tty->index))) {
printk(KERN_WARNING "HVCS: open failed, no device associated"
Expand Down Expand Up @@ -1181,7 +1166,7 @@ static int hvcs_open(struct tty_struct *tty, struct file *filp)
* and will grab the spinlock and free the connection if it fails.
*/
if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
kobject_put(&hvcsd->kobj);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
printk(KERN_WARNING "HVCS: enable device failed.\n");
return rc;
}
Expand All @@ -1192,17 +1177,11 @@ static int hvcs_open(struct tty_struct *tty, struct file *filp)
hvcsd = tty->driver_data;

spin_lock_irqsave(&hvcsd->lock, flags);
if (!kobject_get(&hvcsd->kobj)) {
spin_unlock_irqrestore(&hvcsd->lock, flags);
printk(KERN_ERR "HVCS: Kobject of open"
" hvcs doesn't exist.\n");
return -EFAULT; /* Is this the right return value? */
}

kref_get(&hvcsd->kref);
hvcsd->open_count++;

hvcsd->todo_mask |= HVCS_SCHED_READ;
spin_unlock_irqrestore(&hvcsd->lock, flags);

open_success:
hvcs_kick();

Expand All @@ -1212,9 +1191,8 @@ static int hvcs_open(struct tty_struct *tty, struct file *filp)
return 0;

error_release:
kobjp = &hvcsd->kobj;
spin_unlock_irqrestore(&hvcsd->lock, flags);
kobject_put(&hvcsd->kobj);
kref_put(&hvcsd->kref, destroy_hvcs_struct);

printk(KERN_WARNING "HVCS: partner connect failed.\n");
return retval;
Expand All @@ -1224,7 +1202,6 @@ static void hvcs_close(struct tty_struct *tty, struct file *filp)
{
struct hvcs_struct *hvcsd;
unsigned long flags;
struct kobject *kobjp;
int irq = NO_IRQ;

/*
Expand All @@ -1245,7 +1222,6 @@ static void hvcs_close(struct tty_struct *tty, struct file *filp)
hvcsd = tty->driver_data;

spin_lock_irqsave(&hvcsd->lock, flags);
kobjp = &hvcsd->kobj;
if (--hvcsd->open_count == 0) {

vio_disable_interrupts(hvcsd->vdev);
Expand All @@ -1270,7 +1246,7 @@ static void hvcs_close(struct tty_struct *tty, struct file *filp)
tty->driver_data = NULL;

free_irq(irq, hvcsd);
kobject_put(kobjp);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
return;
} else if (hvcsd->open_count < 0) {
printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
Expand All @@ -1279,29 +1255,25 @@ static void hvcs_close(struct tty_struct *tty, struct file *filp)
}

spin_unlock_irqrestore(&hvcsd->lock, flags);
kobject_put(kobjp);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
}

static void hvcs_hangup(struct tty_struct * tty)
{
struct hvcs_struct *hvcsd = tty->driver_data;
unsigned long flags;
int temp_open_count;
struct kobject *kobjp;
int irq = NO_IRQ;

spin_lock_irqsave(&hvcsd->lock, flags);
/* Preserve this so that we know how many kobject refs to put */
/* Preserve this so that we know how many kref refs to put */
temp_open_count = hvcsd->open_count;

/*
* Don't kobject put inside the spinlock because the destruction
* Don't kref put inside the spinlock because the destruction
* callback may use the spinlock and it may get called before the
* spinlock has been released. Get a pointer to the kobject and
* kobject_put on that after releasing the spinlock.
* spinlock has been released.
*/
kobjp = &hvcsd->kobj;

vio_disable_interrupts(hvcsd->vdev);

hvcsd->todo_mask = 0;
Expand All @@ -1324,7 +1296,7 @@ static void hvcs_hangup(struct tty_struct * tty)
free_irq(irq, hvcsd);

/*
* We need to kobject_put() for every open_count we have since the
* We need to kref_put() for every open_count we have since the
* tty_hangup() function doesn't invoke a close per open connection on a
* non-console device.
*/
Expand All @@ -1335,7 +1307,7 @@ static void hvcs_hangup(struct tty_struct * tty)
* NOTE: If this hangup was signaled from user space then the
* final put will never happen.
*/
kobject_put(kobjp);
kref_put(&hvcsd->kref, destroy_hvcs_struct);
}
}

Expand Down

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