firewire: Implement proper transaction cancelation.

Drivers such as fw-sbp2 had no way to properly cancel in-progress
transactions, which could leave a pending transaction or an unset
packet in the low-level queues after kfree'ing the containing
structure. fw_cancel_transaction() lets drivers cancel a submitted
transaction.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/fw-card.c

@@ -474,6 +474,12 @@ dummy_send_response(struct fw_card *card, struct fw_packet *packet)
 	packet->callback(packet, card, -ENODEV);
 }
 
+static int
+dummy_cancel_packet(struct fw_card *card, struct fw_packet *packet)
+{
+	return -ENOENT;
+}
+
 static int
 dummy_enable_phys_dma(struct fw_card *card,
 		      int node_id, int generation)
@@ -487,6 +493,7 @@ static struct fw_card_driver dummy_driver = {
 	.update_phy_reg  = dummy_update_phy_reg,
 	.set_config_rom  = dummy_set_config_rom,
 	.send_request    = dummy_send_request,
+	.cancel_packet   = dummy_cancel_packet,
 	.send_response   = dummy_send_response,
 	.enable_phys_dma = dummy_enable_phys_dma,
 };

drivers/firewire/fw-ohci.c

@@ -79,6 +79,7 @@ struct at_context {
 	struct fw_ohci *ohci;
 	dma_addr_t descriptor_bus;
 	dma_addr_t buffer_bus;
+	struct fw_packet *current_packet;
 
 	struct list_head list;
 
@@ -489,6 +490,7 @@ at_context_setup_packet(struct at_context *ctx, struct list_head *list)
 			  ctx->descriptor_bus | z);
 		reg_write(ctx->ohci, control_set(ctx->regs),
 			  CONTEXT_RUN | CONTEXT_WAKE);
+		ctx->current_packet = packet;
 	} else {
 		/* We dont return error codes from this function; all
 		 * transmission errors are reported through the
@@ -524,6 +526,12 @@ static void at_context_tasklet(unsigned long data)
 
 	at_context_stop(ctx);
 
+	/* If the head of the list isn't the packet that just got
+	 * transmitted, the packet got cancelled before we finished
+	 * transmitting it. */
+	if (ctx->current_packet != packet)
+		goto skip_to_next;
+
 	if (packet->payload_length > 0) {
 		dma_unmap_single(ohci->card.device, packet->payload_bus,
 				 packet->payload_length, DMA_TO_DEVICE);
@@ -564,6 +572,7 @@ static void at_context_tasklet(unsigned long data)
 	} else
 		complete_transmission(packet, evt - 16, &list);
 
+ skip_to_next:
 	/* If more packets are queued, set up the next one. */
 	if (!list_empty(&ctx->list))
 		at_context_setup_packet(ctx, &list);
@@ -1012,6 +1021,29 @@ static void ohci_send_response(struct fw_card *card, struct fw_packet *packet)
 	at_context_transmit(&ohci->at_response_ctx, packet);
 }
 
+static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
+{
+	struct fw_ohci *ohci = fw_ohci(card);
+	LIST_HEAD(list);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ohci->lock, flags);
+
+	if (packet->ack == 0) {
+		fw_notify("cancelling packet %p (header[0]=%08x)\n",
+			  packet, packet->header[0]);
+
+		complete_transmission(packet, RCODE_CANCELLED, &list);
+	}
+
+	spin_unlock_irqrestore(&ohci->lock, flags);
+
+	do_packet_callbacks(ohci, &list);
+
+	/* Return success if we actually cancelled something. */
+	return list_empty(&list) ? -ENOENT : 0;
+}
+
 static int
 ohci_enable_phys_dma(struct fw_card *card, int node_id, int generation)
 {
@@ -1339,6 +1371,7 @@ static const struct fw_card_driver ohci_driver = {
 	.set_config_rom		= ohci_set_config_rom,
 	.send_request		= ohci_send_request,
 	.send_response		= ohci_send_response,
+	.cancel_packet		= ohci_cancel_packet,
 	.enable_phys_dma	= ohci_enable_phys_dma,
 
 	.allocate_iso_context	= ohci_allocate_iso_context,

drivers/firewire/fw-sbp2.c

@@ -348,6 +348,9 @@ static void sbp2_cancel_orbs(struct fw_unit *unit)
 	spin_unlock_irqrestore(&device->card->lock, flags);
 
 	list_for_each_entry_safe(orb, next, &list, link) {
+		if (fw_cancel_transaction(device->card, &orb->t) == 0)
+			continue;
+
 		orb->rcode = RCODE_CANCELLED;
 		orb->callback(orb, NULL);
 	}

drivers/firewire/fw-transaction.c

@@ -59,20 +59,52 @@
 #define phy_config_root_id(node_id)	((((node_id) & 0x3f) << 24) | (1 << 23))
 #define phy_identifier(id)		((id) << 30)
 
-static void
-close_transaction(struct fw_transaction *t, struct fw_card *card, int rcode,
+static int
+close_transaction(struct fw_transaction *transaction,
+		  struct fw_card *card, int rcode,
 		  u32 *payload, size_t length)
 {
+	struct fw_transaction *t;
 	unsigned long flags;
 
 	spin_lock_irqsave(&card->lock, flags);
-	card->tlabel_mask &= ~(1 << t->tlabel);
+	list_for_each_entry(t, &card->transaction_list, link) {
+		if (t == transaction) {
 			list_del(&t->link);
+			card->tlabel_mask &= ~(1 << t->tlabel);
+			break;
+		}
+	}
 	spin_unlock_irqrestore(&card->lock, flags);
 
+	if (&t->link != &card->transaction_list) {
 		t->callback(card, rcode, payload, length, t->callback_data);
+		return 0;
 	}
 
+	return -ENOENT;
+}
+
+/* Only valid for transactions that are potentially pending (ie have
+ * been sent). */
+int
+fw_cancel_transaction(struct fw_card *card,
+		      struct fw_transaction *transaction)
+{
+	/* Cancel the packet transmission if it's still queued.  That
+	 * will call the packet transmission callback which cancels
+	 * the transaction. */
+
+	if (card->driver->cancel_packet(card, &transaction->packet) == 0)
+		return 0;
+
+	/* If the request packet has already been sent, we need to see
+	 * if the transaction is still pending and remove it in that case. */
+
+	return close_transaction(transaction, card, RCODE_CANCELLED, NULL, 0);
+}
+EXPORT_SYMBOL(fw_cancel_transaction);
+
 static void
 transmit_complete_callback(struct fw_packet *packet,
 			   struct fw_card *card, int status)
@@ -162,6 +194,7 @@ fw_fill_request(struct fw_packet *packet, int tcode, int tlabel,
 
 	packet->speed = speed;
 	packet->generation = generation;
+	packet->ack = 0;
 }
 
 /**
@@ -298,9 +331,15 @@ void fw_flush_transactions(struct fw_card *card)
 	card->tlabel_mask = 0;
 	spin_unlock_irqrestore(&card->lock, flags);
 
-	list_for_each_entry_safe(t, next, &list, link)
+	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,
@@ -531,6 +570,7 @@ allocate_request(struct fw_packet *p)
 	request->response.speed = p->speed;
 	request->response.timestamp = t;
 	request->response.generation = p->generation;
+	request->response.ack = 0;
 	request->response.callback = free_response_callback;
 	request->ack = p->ack;
 	request->length = length;

drivers/firewire/fw-transaction.h

@@ -391,6 +391,8 @@ struct fw_card_driver {
 
 	void (*send_request) (struct fw_card *card, struct fw_packet *packet);
 	void (*send_response) (struct fw_card *card, struct fw_packet *packet);
+	/* Calling cancel is valid once a packet has been submitted. */
+	int (*cancel_packet) (struct fw_card *card, struct fw_packet *packet);
 
 	/* Allow the specified node ID to do direct DMA out and in of
 	 * host memory.  The card will disable this for all node when
@@ -421,6 +423,9 @@ fw_send_request(struct fw_card *card, struct fw_transaction *t,
 		void *data, size_t length,
 		fw_transaction_callback_t callback, void *callback_data);
 
+int fw_cancel_transaction(struct fw_card *card,
+			  struct fw_transaction *transaction);
+
 void fw_flush_transactions(struct fw_card *card);
 
 void fw_send_phy_config(struct fw_card *card,