firewire: core: use separate timeout for each transaction

Using a single timeout for all transaction that need to be flushed does
not work if the submission of new transactions can defer the timeout
indefinitely into the future.  We need to have timeouts that do not
change due to other transactions; the simplest way to do this is with a
separate timer for each transaction.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (+ one lockdep annotation)

drivers/firewire/core-card.c

@@ -30,7 +30,6 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
-#include <linux/timer.h>
 #include <linux/workqueue.h>
 
 #include <asm/atomic.h>
@@ -408,13 +407,6 @@ static void fw_card_bm_work(struct work_struct *work)
 	fw_card_put(card);
 }
 
-static void flush_timer_callback(unsigned long data)
-{
-	struct fw_card *card = (struct fw_card *)data;
-
-	fw_flush_transactions(card);
-}
-
 void fw_card_initialize(struct fw_card *card,
 			const struct fw_card_driver *driver,
 			struct device *device)
@@ -433,8 +425,6 @@ void fw_card_initialize(struct fw_card *card,
 	init_completion(&card->done);
 	INIT_LIST_HEAD(&card->transaction_list);
 	spin_lock_init(&card->lock);
-	setup_timer(&card->flush_timer,
-		    flush_timer_callback, (unsigned long)card);
 
 	card->local_node = NULL;
 
@@ -559,7 +549,6 @@ void fw_core_remove_card(struct fw_card *card)
 	wait_for_completion(&card->done);
 
 	WARN_ON(!list_empty(&card->transaction_list));
-	del_timer_sync(&card->flush_timer);
 }
 EXPORT_SYMBOL(fw_core_remove_card);
 

drivers/firewire/core-transaction.c

@@ -81,7 +81,7 @@ static int close_transaction(struct fw_transaction *transaction,
 	spin_lock_irqsave(&card->lock, flags);
 	list_for_each_entry(t, &card->transaction_list, link) {
 		if (t == transaction) {
-			list_del(&t->link);
+			list_del_init(&t->link);
 			card->tlabel_mask &= ~(1ULL << t->tlabel);
 			break;
 		}
@@ -89,6 +89,7 @@ static int close_transaction(struct fw_transaction *transaction,
 	spin_unlock_irqrestore(&card->lock, flags);
 
 	if (&t->link != &card->transaction_list) {
+		del_timer_sync(&t->split_timeout_timer);
 		t->callback(card, rcode, NULL, 0, t->callback_data);
 		return 0;
 	}
@@ -121,6 +122,31 @@ int fw_cancel_transaction(struct fw_card *card,
 }
 EXPORT_SYMBOL(fw_cancel_transaction);
 
+static void split_transaction_timeout_callback(unsigned long data)
+{
+	struct fw_transaction *t = (struct fw_transaction *)data;
+	struct fw_card *card = t->card;
+	unsigned long flags;
+
+	spin_lock_irqsave(&card->lock, flags);
+	if (list_empty(&t->link)) {
+		spin_unlock_irqrestore(&card->lock, flags);
+		return;
+	}
+	list_del(&t->link);
+	card->tlabel_mask &= ~(1ULL << t->tlabel);
+	spin_unlock_irqrestore(&card->lock, flags);
+
+	card->driver->cancel_packet(card, &t->packet);
+
+	/*
+	 * At this point cancel_packet will never call the transaction
+	 * callback, since we just took the transaction out of the list.
+	 * So do it here.
+	 */
+	t->callback(card, RCODE_CANCELLED, NULL, 0, t->callback_data);
+}
+
 static void transmit_complete_callback(struct fw_packet *packet,
 				       struct fw_card *card, int status)
 {
@@ -293,13 +319,6 @@ void fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode,
 	unsigned long flags;
 	int tlabel;
 
-	/*
-	 * Bump the flush timer up 100ms first of all so we
-	 * don't race with a flush timer callback.
-	 */
-
-	mod_timer(&card->flush_timer, jiffies + DIV_ROUND_UP(HZ, 10));
-
 	/*
 	 * Allocate tlabel from the bitmap and put the transaction on
 	 * the list while holding the card spinlock.
@@ -316,6 +335,11 @@ void fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode,
 
 	t->node_id = destination_id;
 	t->tlabel = tlabel;
+	t->card = card;
+	setup_timer(&t->split_timeout_timer,
+		    split_transaction_timeout_callback, (unsigned long)t);
+	/* FIXME: start this timer later, relative to t->timestamp */
+	mod_timer(&t->split_timeout_timer, jiffies + DIV_ROUND_UP(HZ, 10));
 	t->callback = callback;
 	t->callback_data = callback_data;
 
@@ -361,11 +385,13 @@ int fw_run_transaction(struct fw_card *card, int tcode, int destination_id,
 	struct transaction_callback_data d;
 	struct fw_transaction t;
 
+	init_timer_on_stack(&t.split_timeout_timer);
 	init_completion(&d.done);
 	d.payload = payload;
 	fw_send_request(card, &t, tcode, destination_id, generation, speed,
 			offset, payload, length, transaction_callback, &d);
 	wait_for_completion(&d.done);
+	destroy_timer_on_stack(&t.split_timeout_timer);
 
 	return d.rcode;
 }
@@ -408,30 +434,6 @@ void fw_send_phy_config(struct fw_card *card,
 	mutex_unlock(&phy_config_mutex);
 }
 
-void fw_flush_transactions(struct fw_card *card)
-{
-	struct fw_transaction *t, *next;
-	struct list_head list;
-	unsigned long flags;
-
-	INIT_LIST_HEAD(&list);
-	spin_lock_irqsave(&card->lock, flags);
-	list_splice_init(&card->transaction_list, &list);
-	card->tlabel_mask = 0;
-	spin_unlock_irqrestore(&card->lock, flags);
-
-	list_for_each_entry_safe(t, next, &list, link) {
-		card->driver->cancel_packet(card, &t->packet);
-
-		/*
-		 * At this point cancel_packet will never call the
-		 * transaction callback, since we just took all the
-		 * transactions out of the list.  So do it here.
-		 */
-		t->callback(card, RCODE_CANCELLED, NULL, 0, t->callback_data);
-	}
-}
-
 static struct fw_address_handler *lookup_overlapping_address_handler(
 	struct list_head *list, unsigned long long offset, size_t length)
 {
@@ -841,7 +843,7 @@ void fw_core_handle_response(struct fw_card *card, struct fw_packet *p)
 	spin_lock_irqsave(&card->lock, flags);
 	list_for_each_entry(t, &card->transaction_list, link) {
 		if (t->node_id == source && t->tlabel == tlabel) {
-			list_del(&t->link);
+			list_del_init(&t->link);
 			card->tlabel_mask &= ~(1ULL << t->tlabel);
 			break;
 		}
@@ -883,6 +885,8 @@ void fw_core_handle_response(struct fw_card *card, struct fw_packet *p)
 		break;
 	}
 
+	del_timer_sync(&t->split_timeout_timer);
+
 	/*
 	 * The response handler may be executed while the request handler
 	 * is still pending.  Cancel the request handler.

drivers/firewire/core.h

@@ -220,7 +220,6 @@ void fw_core_handle_request(struct fw_card *card, struct fw_packet *request);
 void fw_core_handle_response(struct fw_card *card, struct fw_packet *packet);
 void fw_fill_response(struct fw_packet *response, u32 *request_header,
 		      int rcode, void *payload, size_t length);
-void fw_flush_transactions(struct fw_card *card);
 void fw_send_phy_config(struct fw_card *card,
 			int node_id, int generation, int gap_count);
 

include/linux/firewire.h

@@ -87,7 +87,6 @@ struct fw_card {
 	int current_tlabel;
 	u64 tlabel_mask;
 	struct list_head transaction_list;
-	struct timer_list flush_timer;
 	unsigned long reset_jiffies;
 
 	unsigned long long guid;
@@ -288,6 +287,8 @@ struct fw_transaction {
 	int tlabel;
 	int timestamp;
 	struct list_head link;
+	struct fw_card *card;
+	struct timer_list split_timeout_timer;
 
 	struct fw_packet packet;