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Date: Sat, 24 May 2008 16:50:22 +0200 (CEST)
From: Stefan Richter <stefanr@...6.in-berlin.de>
To: linux1394-devel@...ts.sourceforge.net
cc: linux-kernel@...r.kernel.org,
Kristian Høgsberg <krh@...planet.net>
Subject: [PATCH] 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@...6.in-berlin.de>
---
Applies after patch "firewire: clean up some includes".
drivers/firewire/fw-card.c | 30 ++++++++++++++++++++----------
drivers/firewire/fw-device.c | 5 ++---
drivers/firewire/fw-transaction.h | 20 ++++++++++++++++++--
3 files changed, 40 insertions(+), 15 deletions(-)
Index: linux/drivers/firewire/fw-card.c
===================================================================
--- linux.orig/drivers/firewire/fw-card.c
+++ linux/drivers/firewire/fw-card.c
@@ -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,
{
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,
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,
@@ -507,6 +511,14 @@ static struct fw_card_driver dummy_drive
};
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)
{
card->driver->update_phy_reg(card, 4,
@@ -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);
Index: linux/drivers/firewire/fw-device.c
===================================================================
--- linux.orig/drivers/firewire/fw-device.c
+++ linux/drivers/firewire/fw-device.c
@@ -167,7 +167,7 @@ static void fw_device_release(struct 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)
@@ -945,8 +945,7 @@ void fw_node_event(struct fw_card *card,
*/
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;
Index: linux/drivers/firewire/fw-transaction.h
===================================================================
--- linux.orig/drivers/firewire/fw-transaction.h
+++ linux/drivers/firewire/fw-transaction.h
@@ -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);
+}
+
/*
* Check whether new_generation is the immediate successor of old_generation.
* Take counter roll-over at 255 (as per to OHCI) into account.
--
Stefan Richter
-=====-==--- -=-= ==---
http://arcgraph.de/sr/
--
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