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firewire: clean up fw_card reference counting 

This is a functionally equivalent replacement of the current reference
counting of struct fw_card instances.  It only converts it to common
idioms as suggested by Kristian Høgsberg:
  - struct kref replaces atomic_t as the counter.
  - wait_for_completion is used to wait for all card users to complete.

BTW, it may make sense to count card->flush_timer and card->work as
card users too.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2008-05-24 16:50:22 +02:00
parent 2147ef204f
commit 459f79235d
3 changed files with 40 additions and 15 deletions
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30
drivers/firewire/fw-card.c
View File

@ -16,12 +16,15 @@
* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/completion.h>
#include <linux/crc-itu-t.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/crc-itu-t.h>
#include "fw-transaction.h"
#include "fw-topology.h"
#include "fw-device.h"
@ -396,7 +399,6 @@ fw_card_initialize(struct fw_card *card, const struct fw_card_driver *driver,
{
static atomic_t index = ATOMIC_INIT(-1);
atomic_set(&card->device_count, 0);
card->index = atomic_inc_return(&index);
card->driver = driver;
card->device = device;
@ -405,6 +407,8 @@ fw_card_initialize(struct fw_card *card, const struct fw_card_driver *driver,
card->color = 0;
card->broadcast_channel = BROADCAST_CHANNEL_INITIAL;
kref_init(&card->kref);
init_completion(&card->done);
INIT_LIST_HEAD(&card->transaction_list);
spin_lock_init(&card->lock);
setup_timer(&card->flush_timer,
@ -506,6 +510,14 @@ static struct fw_card_driver dummy_driver = {
.enable_phys_dma = dummy_enable_phys_dma,
};
void
fw_card_release(struct kref *kref)
{
struct fw_card *card = container_of(kref, struct fw_card, kref);
complete(&card->done);
}
void
fw_core_remove_card(struct fw_card *card)
{
@ -521,12 +533,10 @@ fw_core_remove_card(struct fw_card *card)
card->driver = &dummy_driver;
fw_destroy_nodes(card);
/*
* Wait for all device workqueue jobs to finish. Otherwise the
* firewire-core module could be unloaded before the jobs ran.
*/
while (atomic_read(&card->device_count) > 0)
msleep(100);
/* Wait for all users, especially device workqueue jobs, to finish. */
fw_card_put(card);
wait_for_completion(&card->done);
cancel_delayed_work_sync(&card->work);
fw_flush_transactions(card);

5
drivers/firewire/fw-device.c
View File

@ -168,7 +168,7 @@ static void fw_device_release(struct device *dev)
fw_node_put(device->node);
kfree(device->config_rom);
kfree(device);
atomic_dec(&card->device_count);
fw_card_put(card);
}
int fw_device_enable_phys_dma(struct fw_device *device)
@ -946,8 +946,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
*/
device_initialize(&device->device);
atomic_set(&device->state, FW_DEVICE_INITIALIZING);
atomic_inc(&card->device_count);
device->card = card;
device->card = fw_card_get(card);
device->node = fw_node_get(node);
device->node_id = node->node_id;
device->generation = card->generation;

20
drivers/firewire/fw-transaction.h
View File

@ -19,14 +19,15 @@
#ifndef __fw_transaction_h
#define __fw_transaction_h
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/firewire-constants.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/spinlock_types.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <asm/atomic.h>
#define TCODE_IS_READ_REQUEST(tcode) (((tcode) & ~1) == 4)
#define TCODE_IS_BLOCK_PACKET(tcode) (((tcode) & 1) != 0)
@ -219,7 +220,8 @@ extern struct bus_type fw_bus_type;
struct fw_card {
const struct fw_card_driver *driver;
struct device *device;
atomic_t device_count;
struct kref kref;
struct completion done;
int node_id;
int generation;
@ -260,6 +262,20 @@ struct fw_card {
int bm_generation;
};
static inline struct fw_card *fw_card_get(struct fw_card *card)
{
kref_get(&card->kref);
return card;
}
void fw_card_release(struct kref *kref);
static inline void fw_card_put(struct fw_card *card)
{
kref_put(&card->kref, fw_card_release);
}
/*
* The iso packet format allows for an immediate header/payload part
* stored in 'header' immediately after the packet info plus an