[PATCH v2] firewire: Remove function callback casts

[Oscar Carter <oscar.carter@gmx.com>]

In an effort to enable -Wcast-function-type in the top-level Makefile to
support Control Flow Integrity builds, remove all the function callback
casts.

To do this, modify the "fw_iso_context_create" function prototype adding
a new parameter for the multichannel callback. Also, fix all the
function calls accordingly.

In the "fw_iso_context_create" function return an error code if both
callback parameters are NULL and also set the "ctx->callback.sc"
explicity to NULL in this case. It is not necessary set to NULL the
"ctx->callback.mc" variable because this and "ctx->callback.sc" are an
union and setting one implies setting the other one to the same value.

Signed-off-by: Oscar Carter <oscar.carter@gmx.com>
---
Changelog v1->v2
-Set explicity to NULL the "ctx->callback.sc" variable and return an error
 code in "fw_iso_context_create" function if both callback parameters are
 NULL as Lev R. Oshvang suggested.
-Modify the commit changelog accordingly.

 drivers/firewire/core-cdev.c        | 12 +++++++-----
 drivers/firewire/core-iso.c         | 14 ++++++++++++--
 drivers/firewire/net.c              |  2 +-
 drivers/media/firewire/firedtv-fw.c |  3 ++-
 include/linux/firewire.h            |  3 ++-
 sound/firewire/amdtp-stream.c       |  2 +-
 sound/firewire/isight.c             |  4 ++--
 7 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 6e291d8f3a27..cc368b35be2e 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -957,7 +957,8 @@ static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
 {
 	struct fw_cdev_create_iso_context *a = &arg->create_iso_context;
 	struct fw_iso_context *context;
-	fw_iso_callback_t cb;
+	fw_iso_callback_t cb_sc = NULL;
+	fw_iso_mc_callback_t cb_mc = NULL;
 	int ret;

 	BUILD_BUG_ON(FW_CDEV_ISO_CONTEXT_TRANSMIT != FW_ISO_CONTEXT_TRANSMIT ||
@@ -970,7 +971,7 @@ static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
 		if (a->speed > SCODE_3200 || a->channel > 63)
 			return -EINVAL;

-		cb = iso_callback;
+		cb_sc = iso_callback;
 		break;

 	case FW_ISO_CONTEXT_RECEIVE:
@@ -978,11 +979,11 @@ static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
 		    a->channel > 63)
 			return -EINVAL;

-		cb = iso_callback;
+		cb_sc = iso_callback;
 		break;

 	case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
-		cb = (fw_iso_callback_t)iso_mc_callback;
+		cb_mc = iso_mc_callback;
 		break;

 	default:
@@ -990,7 +991,8 @@ static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
 	}

 	context = fw_iso_context_create(client->device->card, a->type,
-			a->channel, a->speed, a->header_size, cb, client);
+			a->channel, a->speed, a->header_size, cb_sc, cb_mc,
+			client);
 	if (IS_ERR(context))
 		return PTR_ERR(context);
 	if (client->version < FW_CDEV_VERSION_AUTO_FLUSH_ISO_OVERFLOW)
diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 185b0b78b3d6..1d28a98c08b2 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -131,7 +131,8 @@ size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)

 struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
 		int type, int channel, int speed, size_t header_size,
-		fw_iso_callback_t callback, void *callback_data)
+		fw_iso_callback_t cb_sc, fw_iso_mc_callback_t cb_mc,
+		void *callback_data)
 {
 	struct fw_iso_context *ctx;

@@ -145,7 +146,16 @@ struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
 	ctx->channel = channel;
 	ctx->speed = speed;
 	ctx->header_size = header_size;
-	ctx->callback.sc = callback;
+
+	if (cb_sc) {
+		ctx->callback.sc = cb_sc;
+	} else if (cb_mc) {
+		ctx->callback.mc = cb_mc;
+	} else {
+		ctx->callback.sc = NULL;
+		return ERR_PTR(-EINVAL);
+	}
+
 	ctx->callback_data = callback_data;

 	return ctx;
diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index 715e491dfbc3..c5cc0a311aa0 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -1136,7 +1136,7 @@ static int fwnet_broadcast_start(struct fwnet_device *dev)
 	context = fw_iso_context_create(dev->card, FW_ISO_CONTEXT_RECEIVE,
 					IEEE1394_BROADCAST_CHANNEL,
 					dev->card->link_speed, 8,
-					fwnet_receive_broadcast, dev);
+					fwnet_receive_broadcast, NULL, dev);
 	if (IS_ERR(context)) {
 		retval = PTR_ERR(context);
 		goto failed;
diff --git a/drivers/media/firewire/firedtv-fw.c b/drivers/media/firewire/firedtv-fw.c
index 97144734eb05..d2940adefd8c 100644
--- a/drivers/media/firewire/firedtv-fw.c
+++ b/drivers/media/firewire/firedtv-fw.c
@@ -141,7 +141,8 @@ int fdtv_start_iso(struct firedtv *fdtv)

 	ctx->context = fw_iso_context_create(device->card,
 			FW_ISO_CONTEXT_RECEIVE, fdtv->isochannel,
-			device->max_speed, ISO_HEADER_SIZE, handle_iso, fdtv);
+			device->max_speed, ISO_HEADER_SIZE,
+			handle_iso, NULL, fdtv);
 	if (IS_ERR(ctx->context)) {
 		err = PTR_ERR(ctx->context);
 		goto fail_free;
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index aec8f30ab200..3a0b5e18e140 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -452,7 +452,8 @@ struct fw_iso_context {

 struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
 		int type, int channel, int speed, size_t header_size,
-		fw_iso_callback_t callback, void *callback_data);
+		fw_iso_callback_t cb_sc, fw_iso_mc_callback_t cb_mc,
+		void *callback_data);
 int fw_iso_context_set_channels(struct fw_iso_context *ctx, u64 *channels);
 int fw_iso_context_queue(struct fw_iso_context *ctx,
 			 struct fw_iso_packet *packet,
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 37d38efb4c87..8629ab3e2c64 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -1093,7 +1093,7 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed,

 	s->context = fw_iso_context_create(fw_parent_device(s->unit)->card,
 					  type, channel, speed, ctx_header_size,
-					  ctx_cb, ctx_data);
+					  ctx_cb, NULL, ctx_data);
 	if (IS_ERR(s->context)) {
 		err = PTR_ERR(s->context);
 		if (err == -EBUSY)
diff --git a/sound/firewire/isight.c b/sound/firewire/isight.c
index 6655af53b367..51cc37fca736 100644
--- a/sound/firewire/isight.c
+++ b/sound/firewire/isight.c
@@ -361,8 +361,8 @@ static int isight_start_streaming(struct isight *isight)
 	isight->context = fw_iso_context_create(isight->device->card,
 						FW_ISO_CONTEXT_RECEIVE,
 						isight->resources.channel,
-						isight->device->max_speed,
-						4, isight_packet, isight);
+						isight->device->max_speed, 4,
+						isight_packet, NULL, isight);
 	if (IS_ERR(isight->context)) {
 		err = PTR_ERR(isight->context);
 		isight->context = NULL;
--
2.20.1