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kobject: convert hvc_console to use kref, not kobject
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hvc_console 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 <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Ryan S. Arnold <[email protected]>
Cc: Kay Sievers <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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@gregkh
gregkh committed Jan 25, 2008
1 parent a045171 commit 12b20de
Showing 1 changed file with 33 additions and 47 deletions.
80 changes: 33 additions & 47 deletions drivers/char/hvc_console.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
#include <linux/init.h>
#include <linux/kbd_kern.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/kref.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/module.h>
Expand Down Expand Up @@ -89,7 +89,7 @@ struct hvc_struct {
int irq_requested;
int irq;
struct list_head next;
struct kobject kobj; /* ref count & hvc_struct lifetime */
struct kref kref; /* ref count & hvc_struct lifetime */
};

/* dynamic list of hvc_struct instances */
Expand All @@ -110,7 +110,7 @@ static int last_hvc = -1;

/*
* Do not call this function with either the hvc_structs_lock or the hvc_struct
* lock held. If successful, this function increments the kobject reference
* lock held. If successful, this function increments the kref reference
* count against the target hvc_struct so it should be released when finished.
*/
static struct hvc_struct *hvc_get_by_index(int index)
Expand All @@ -123,7 +123,7 @@ static struct hvc_struct *hvc_get_by_index(int index)
list_for_each_entry(hp, &hvc_structs, next) {
spin_lock_irqsave(&hp->lock, flags);
if (hp->index == index) {
kobject_get(&hp->kobj);
kref_get(&hp->kref);
spin_unlock_irqrestore(&hp->lock, flags);
spin_unlock(&hvc_structs_lock);
return hp;
Expand Down Expand Up @@ -242,6 +242,23 @@ static int __init hvc_console_init(void)
}
console_initcall(hvc_console_init);

/* callback when the kboject ref count reaches zero. */
static void destroy_hvc_struct(struct kref *kref)
{
struct hvc_struct *hp = container_of(kref, struct hvc_struct, kref);
unsigned long flags;

spin_lock(&hvc_structs_lock);

spin_lock_irqsave(&hp->lock, flags);
list_del(&(hp->next));
spin_unlock_irqrestore(&hp->lock, flags);

spin_unlock(&hvc_structs_lock);

kfree(hp);
}

/*
* hvc_instantiate() is an early console discovery method which locates
* consoles * prior to the vio subsystem discovering them. Hotplugged
Expand All @@ -261,7 +278,7 @@ int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
/* make sure no no tty has been registered in this index */
hp = hvc_get_by_index(index);
if (hp) {
kobject_put(&hp->kobj);
kref_put(&hp->kref, destroy_hvc_struct);
return -1;
}

Expand Down Expand Up @@ -318,9 +335,8 @@ static int hvc_open(struct tty_struct *tty, struct file * filp)
unsigned long flags;
int irq = 0;
int rc = 0;
struct kobject *kobjp;

/* Auto increments kobject reference if found. */
/* Auto increments kref reference if found. */
if (!(hp = hvc_get_by_index(tty->index)))
return -ENODEV;

Expand All @@ -341,8 +357,6 @@ static int hvc_open(struct tty_struct *tty, struct file * filp)
if (irq)
hp->irq_requested = 1;

kobjp = &hp->kobj;

spin_unlock_irqrestore(&hp->lock, flags);
/* check error, fallback to non-irq */
if (irq)
Expand All @@ -352,15 +366,15 @@ static int hvc_open(struct tty_struct *tty, struct file * filp)
* If the request_irq() fails and we return an error. The tty layer
* will call hvc_close() after a failed open but we don't want to clean
* up there so we'll clean up here and clear out the previously set
* tty fields and return the kobject reference.
* tty fields and return the kref reference.
*/
if (rc) {
spin_lock_irqsave(&hp->lock, flags);
hp->tty = NULL;
hp->irq_requested = 0;
spin_unlock_irqrestore(&hp->lock, flags);
tty->driver_data = NULL;
kobject_put(kobjp);
kref_put(&hp->kref, destroy_hvc_struct);
printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
}
/* Force wakeup of the polling thread */
Expand All @@ -372,7 +386,6 @@ static int hvc_open(struct tty_struct *tty, struct file * filp)
static void hvc_close(struct tty_struct *tty, struct file * filp)
{
struct hvc_struct *hp;
struct kobject *kobjp;
int irq = 0;
unsigned long flags;

Expand All @@ -382,15 +395,14 @@ static void hvc_close(struct tty_struct *tty, struct file * filp)
/*
* No driver_data means that this close was issued after a failed
* hvc_open by the tty layer's release_dev() function and we can just
* exit cleanly because the kobject reference wasn't made.
* exit cleanly because the kref reference wasn't made.
*/
if (!tty->driver_data)
return;

hp = tty->driver_data;
spin_lock_irqsave(&hp->lock, flags);

kobjp = &hp->kobj;
if (--hp->count == 0) {
if (hp->irq_requested)
irq = hp->irq;
Expand All @@ -417,7 +429,7 @@ static void hvc_close(struct tty_struct *tty, struct file * filp)
spin_unlock_irqrestore(&hp->lock, flags);
}

kobject_put(kobjp);
kref_put(&hp->kref, destroy_hvc_struct);
}

static void hvc_hangup(struct tty_struct *tty)
Expand All @@ -426,7 +438,6 @@ static void hvc_hangup(struct tty_struct *tty)
unsigned long flags;
int irq = 0;
int temp_open_count;
struct kobject *kobjp;

if (!hp)
return;
Expand All @@ -443,7 +454,6 @@ static void hvc_hangup(struct tty_struct *tty)
return;
}

kobjp = &hp->kobj;
temp_open_count = hp->count;
hp->count = 0;
hp->n_outbuf = 0;
Expand All @@ -457,7 +467,7 @@ static void hvc_hangup(struct tty_struct *tty)
free_irq(irq, hp);
while(temp_open_count) {
--temp_open_count;
kobject_put(kobjp);
kref_put(&hp->kref, destroy_hvc_struct);
}
}

Expand Down Expand Up @@ -729,27 +739,6 @@ static const struct tty_operations hvc_ops = {
.chars_in_buffer = hvc_chars_in_buffer,
};

/* callback when the kboject ref count reaches zero. */
static void destroy_hvc_struct(struct kobject *kobj)
{
struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
unsigned long flags;

spin_lock(&hvc_structs_lock);

spin_lock_irqsave(&hp->lock, flags);
list_del(&(hp->next));
spin_unlock_irqrestore(&hp->lock, flags);

spin_unlock(&hvc_structs_lock);

kfree(hp);
}

static struct kobj_type hvc_kobj_type = {
.release = destroy_hvc_struct,
};

struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
struct hv_ops *ops, int outbuf_size)
{
Expand All @@ -776,8 +765,7 @@ struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
hp->outbuf_size = outbuf_size;
hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];

kobject_init(&hp->kobj);
hp->kobj.ktype = &hvc_kobj_type;
kref_init(&hp->kref);

spin_lock_init(&hp->lock);
spin_lock(&hvc_structs_lock);
Expand Down Expand Up @@ -806,12 +794,10 @@ struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
int __devexit hvc_remove(struct hvc_struct *hp)
{
unsigned long flags;
struct kobject *kobjp;
struct tty_struct *tty;

spin_lock_irqsave(&hp->lock, flags);
tty = hp->tty;
kobjp = &hp->kobj;

if (hp->index < MAX_NR_HVC_CONSOLES)
vtermnos[hp->index] = -1;
Expand All @@ -821,12 +807,12 @@ int __devexit hvc_remove(struct hvc_struct *hp)
spin_unlock_irqrestore(&hp->lock, flags);

/*
* We 'put' the instance that was grabbed when the kobject instance
* was initialized using kobject_init(). Let the last holder of this
* kobject cause it to be removed, which will probably be the tty_hangup
* We 'put' the instance that was grabbed when the kref instance
* was initialized using kref_init(). Let the last holder of this
* kref cause it to be removed, which will probably be the tty_hangup
* below.
*/
kobject_put(kobjp);
kref_put(&hp->kref, destroy_hvc_struct);

/*
* This function call will auto chain call hvc_hangup. The tty should
Expand Down

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