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>

diff --git a/drivers/firewire/fw-card.c b/drivers/firewire/fw-card.c
index 1332b66ae0b395fd485c9ec9671db33e1289f72a..da873d795aad94bccf9e88a58a4b9bde9821daf1 100644 (file)
--- a/drivers/firewire/fw-card.c
+++ b/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, 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);

diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index d9c8daf7ae7d798b29a728464e1365c2fbe10b22..0855fb5568e806cf92546e466b73a702e9f55de6 100644 (file)
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -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;

diff --git a/drivers/firewire/fw-transaction.h b/drivers/firewire/fw-transaction.h
index 219094e38542817d8cd31c701530c365b5007d8b..2ae1b0d6cb7bdfaa6929ccc06a00d63501acebcf 100644 (file)
--- a/drivers/firewire/fw-transaction.h
+++ b/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);
+}
+
 /*
  * The iso packet format allows for an immediate header/payload part
  * stored in 'header' immediately after the packet info plus an