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>

1 files changed, 18 insertions, 2 deletions

diff --git a/drivers/firewire/fw-transaction.h b/drivers/firewire/fw-transaction.h
index 219094e38542..2ae1b0d6cb7b 100644
--- 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