firewire: fix use of multiple AV/C devices, allow multiple FCP listeners

Control of more than one AV/C device at once --- e.g. camcorders, tape
decks, audio devices, TV tuners --- failed or worked only unreliably,
depending on driver implementation.  This affected kernelspace and
userspace drivers alike and was caused by firewire-core's inability to
accept multiple registrations of FCP listeners.

The fix allows multiple address handlers to be registered for the FCP
command and response registers.  When a request for these registers is
received, all handlers are invoked, and the Firewire response is
generated by the core and not by any handler.

The cdev API does not change, i.e., userspace is still expected to send
a response for FCP requests; this response is silently ignored.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (changelog, rebased, whitespace)

drivers/firewire/core-cdev.c

@@ -601,8 +601,9 @@ static void release_request(struct client *client,
 	struct inbound_transaction_resource *r = container_of(resource,
 			struct inbound_transaction_resource, resource);
 
-	fw_send_response(client->device->card, r->request,
-			 RCODE_CONFLICT_ERROR);
+	if (r->request)
+		fw_send_response(client->device->card, r->request,
+				 RCODE_CONFLICT_ERROR);
 	kfree(r);
 }
 
@@ -645,7 +646,8 @@ static void handle_request(struct fw_card *card, struct fw_request *request,
  failed:
 	kfree(r);
 	kfree(e);
-	fw_send_response(card, request, RCODE_CONFLICT_ERROR);
+	if (request)
+		fw_send_response(card, request, RCODE_CONFLICT_ERROR);
 }
 
 static void release_address_handler(struct client *client,
@@ -715,15 +717,17 @@ static int ioctl_send_response(struct client *client, void *buffer)
 
 	r = container_of(resource, struct inbound_transaction_resource,
 			 resource);
-	if (request->length < r->length)
-		r->length = request->length;
-
-	if (copy_from_user(r->data, u64_to_uptr(request->data), r->length)) {
-		ret = -EFAULT;
-		goto out;
+	if (r->request) {
+		if (request->length < r->length)
+			r->length = request->length;
+		if (copy_from_user(r->data, u64_to_uptr(request->data),
+				   r->length)) {
+			ret = -EFAULT;
+			goto out;
+		}
+		fw_send_response(client->device->card, r->request,
+				 request->rcode);
 	}
-
-	fw_send_response(client->device->card, r->request, request->rcode);
  out:
 	kfree(r);
 

drivers/firewire/core-transaction.c

@@ -432,14 +432,20 @@ static struct fw_address_handler *lookup_overlapping_address_handler(
 	return NULL;
 }
 
+static bool is_enclosing_handler(struct fw_address_handler *handler,
+				 unsigned long long offset, size_t length)
+{
+	return handler->offset <= offset &&
+		offset + length <= handler->offset + handler->length;
+}
+
 static struct fw_address_handler *lookup_enclosing_address_handler(
 	struct list_head *list, unsigned long long offset, size_t length)
 {
 	struct fw_address_handler *handler;
 
 	list_for_each_entry(handler, list, link) {
-		if (handler->offset <= offset &&
-		    offset + length <= handler->offset + handler->length)
+		if (is_enclosing_handler(handler, offset, length))
 			return handler;
 	}
 
@@ -465,6 +471,12 @@ const struct fw_address_region fw_unit_space_region =
 	{ .start = 0xfffff0000900ULL, .end = 0x1000000000000ULL, };
 #endif  /*  0  */
 
+static bool is_in_fcp_region(u64 offset, size_t length)
+{
+	return offset >= (CSR_REGISTER_BASE | CSR_FCP_COMMAND) &&
+		offset + length <= (CSR_REGISTER_BASE | CSR_FCP_END);
+}
+
 /**
  * fw_core_add_address_handler - register for incoming requests
  * @handler: callback
@@ -477,8 +489,11 @@ const struct fw_address_region fw_unit_space_region =
  * give the details of the particular request.
  *
  * Return value:  0 on success, non-zero otherwise.
+ *
  * The start offset of the handler's address region is determined by
  * fw_core_add_address_handler() and is returned in handler->offset.
+ *
+ * Address allocations are exclusive, except for the FCP registers.
  */
 int fw_core_add_address_handler(struct fw_address_handler *handler,
 				const struct fw_address_region *region)
@@ -498,10 +513,12 @@ int fw_core_add_address_handler(struct fw_address_handler *handler,
 
 	handler->offset = region->start;
 	while (handler->offset + handler->length <= region->end) {
-		other =
-		    lookup_overlapping_address_handler(&address_handler_list,
-						       handler->offset,
-						       handler->length);
+		if (is_in_fcp_region(handler->offset, handler->length))
+			other = NULL;
+		else
+			other = lookup_overlapping_address_handler
+					(&address_handler_list,
+					 handler->offset, handler->length);
 		if (other != NULL) {
 			handler->offset += other->length;
 		} else {
@@ -668,6 +685,9 @@ static struct fw_request *allocate_request(struct fw_packet *p)
 void fw_send_response(struct fw_card *card,
 		      struct fw_request *request, int rcode)
 {
+	if (WARN_ONCE(!request, "invalid for FCP address handlers"))
+		return;
+
 	/* unified transaction or broadcast transaction: don't respond */
 	if (request->ack != ACK_PENDING ||
 	    HEADER_DESTINATION_IS_BROADCAST(request->request_header[0])) {
@@ -686,26 +706,15 @@ void fw_send_response(struct fw_card *card,
 }
 EXPORT_SYMBOL(fw_send_response);
 
-void fw_core_handle_request(struct fw_card *card, struct fw_packet *p)
+static void handle_exclusive_region_request(struct fw_card *card,
+					    struct fw_packet *p,
+					    struct fw_request *request,
+					    unsigned long long offset)
 {
 	struct fw_address_handler *handler;
-	struct fw_request *request;
-	unsigned long long offset;
 	unsigned long flags;
 	int tcode, destination, source;
 
-	if (p->ack != ACK_PENDING && p->ack != ACK_COMPLETE)
-		return;
-
-	request = allocate_request(p);
-	if (request == NULL) {
-		/* FIXME: send statically allocated busy packet. */
-		return;
-	}
-
-	offset      =
-		((unsigned long long)
-		 HEADER_GET_OFFSET_HIGH(p->header[1]) << 32) | p->header[2];
 	tcode       = HEADER_GET_TCODE(p->header[0]);
 	destination = HEADER_GET_DESTINATION(p->header[0]);
 	source      = HEADER_GET_SOURCE(p->header[1]);
@@ -732,6 +741,73 @@ void fw_core_handle_request(struct fw_card *card, struct fw_packet *p)
 					  request->data, request->length,
 					  handler->callback_data);
 }
+
+static void handle_fcp_region_request(struct fw_card *card,
+				      struct fw_packet *p,
+				      struct fw_request *request,
+				      unsigned long long offset)
+{
+	struct fw_address_handler *handler;
+	unsigned long flags;
+	int tcode, destination, source;
+
+	if ((offset != (CSR_REGISTER_BASE | CSR_FCP_COMMAND) &&
+	     offset != (CSR_REGISTER_BASE | CSR_FCP_RESPONSE)) ||
+	    request->length > 0x200) {
+		fw_send_response(card, request, RCODE_ADDRESS_ERROR);
+
+		return;
+	}
+
+	tcode       = HEADER_GET_TCODE(p->header[0]);
+	destination = HEADER_GET_DESTINATION(p->header[0]);
+	source      = HEADER_GET_SOURCE(p->header[1]);
+
+	if (tcode != TCODE_WRITE_QUADLET_REQUEST &&
+	    tcode != TCODE_WRITE_BLOCK_REQUEST) {
+		fw_send_response(card, request, RCODE_TYPE_ERROR);
+
+		return;
+	}
+
+	spin_lock_irqsave(&address_handler_lock, flags);
+	list_for_each_entry(handler, &address_handler_list, link) {
+		if (is_enclosing_handler(handler, offset, request->length))
+			handler->address_callback(card, NULL, tcode,
+						  destination, source,
+						  p->generation, p->speed,
+						  offset, request->data,
+						  request->length,
+						  handler->callback_data);
+	}
+	spin_unlock_irqrestore(&address_handler_lock, flags);
+
+	fw_send_response(card, request, RCODE_COMPLETE);
+}
+
+void fw_core_handle_request(struct fw_card *card, struct fw_packet *p)
+{
+	struct fw_request *request;
+	unsigned long long offset;
+
+	if (p->ack != ACK_PENDING && p->ack != ACK_COMPLETE)
+		return;
+
+	request = allocate_request(p);
+	if (request == NULL) {
+		/* FIXME: send statically allocated busy packet. */
+		return;
+	}
+
+	offset = ((u64)HEADER_GET_OFFSET_HIGH(p->header[1]) << 32) |
+		p->header[2];
+
+	if (!is_in_fcp_region(offset, request->length))
+		handle_exclusive_region_request(card, p, request, offset);
+	else
+		handle_fcp_region_request(card, p, request, offset);
+
+}
 EXPORT_SYMBOL(fw_core_handle_request);
 
 void fw_core_handle_response(struct fw_card *card, struct fw_packet *p)

drivers/media/dvb/firewire/firedtv-fw.c

@@ -202,14 +202,8 @@ static void handle_fcp(struct fw_card *card, struct fw_request *request,
 	unsigned long flags;
 	int su;
 
-	if ((tcode != TCODE_WRITE_QUADLET_REQUEST &&
-	     tcode != TCODE_WRITE_BLOCK_REQUEST) ||
-	    offset != CSR_REGISTER_BASE + CSR_FCP_RESPONSE ||
-	    length == 0 ||
-	    (((u8 *)payload)[0] & 0xf0) != 0) {
-		fw_send_response(card, request, RCODE_TYPE_ERROR);
+	if (length < 2 || (((u8 *)payload)[0] & 0xf0) != 0)
 		return;
-	}
 
 	su = ((u8 *)payload)[1] & 0x7;
 
@@ -230,10 +224,8 @@ static void handle_fcp(struct fw_card *card, struct fw_request *request,
 	}
 	spin_unlock_irqrestore(&node_list_lock, flags);
 
-	if (fdtv) {
+	if (fdtv)
 		avc_recv(fdtv, payload, length);
-		fw_send_response(card, request, RCODE_COMPLETE);
-	}
 }
 
 static struct fw_address_handler fcp_handler = {

include/linux/firewire-cdev.h

@@ -340,6 +340,9 @@ struct fw_cdev_send_response {
  * The @closure field is passed back to userspace in the response event.
  * The @handle field is an out parameter, returning a handle to the allocated
  * range to be used for later deallocation of the range.
+ *
+ * The address range is allocated on all local nodes.  The address allocation
+ * is exclusive except for the FCP command and response registers.
  */
 struct fw_cdev_allocate {
 	__u64 offset;

include/linux/firewire.h

@@ -248,8 +248,8 @@ typedef void (*fw_transaction_callback_t)(struct fw_card *card, int rcode,
 					  void *data, size_t length,
 					  void *callback_data);
 /*
- * Important note:  The callback must guarantee that either fw_send_response()
- * or kfree() is called on the @request.
+ * Important note:  Except for the FCP registers, the callback must guarantee
+ * that either fw_send_response() or kfree() is called on the @request.
  */
 typedef void (*fw_address_callback_t)(struct fw_card *card,
 				      struct fw_request *request,