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* [PATCH] firewire: fix function type cast warning
@ 2020-10-26 21:51 Arnd Bergmann
  2020-10-27  0:13 ` Takashi Sakamoto
  0 siblings, 1 reply; 3+ messages in thread
From: Arnd Bergmann @ 2020-10-26 21:51 UTC (permalink / raw)
  To: Stefan Richter
  Cc: Arnd Bergmann, Gustavo A. R. Silva, linux1394-devel, linux-kernel

From: Arnd Bergmann <arnd@arndb.de>

gcc -Wextra complains about a suspicious cast:

rivers/firewire/core-cdev.c:985:8: warning: cast between incompatible function types from ‘void (*)(struct fw_iso_context *, dma_addr_t,  void *)’ {aka ‘void (*)(struct fw_iso_context *, long long unsigned int,  void *)’} to ‘void (*)(struct fw_iso_context *, u32,  size_t,  void *, void *)’ {aka ‘void (*)(struct fw_iso_context *, unsigned int,  long unsigned int,  void *, void *)’} [-Wcast-function-type]

The behavior is correct in the end, but this is more clearly
expressed using a transparent union.

Fixes: 872e330e3880 ("firewire: add isochronous multichannel reception")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/firewire/core-cdev.c |  6 +++---
 drivers/firewire/core-iso.c  |  2 +-
 include/linux/firewire.h     | 17 ++++++++---------
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index fb6c651214f3..8d85d52b02ca 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -970,7 +970,7 @@ 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 +978,11 @@ 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:
diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index af70e74f9a7e..ddada648775a 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -145,7 +145,7 @@ 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;
+	ctx->callback = callback;
 	ctx->callback_data = callback_data;
 
 	return ctx;
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index aec8f30ab200..59b5e02a6d42 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -431,11 +431,13 @@ void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer, struct fw_card *card);
 size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed);
 
 struct fw_iso_context;
-typedef void (*fw_iso_callback_t)(struct fw_iso_context *context,
-				  u32 cycle, size_t header_length,
-				  void *header, void *data);
-typedef void (*fw_iso_mc_callback_t)(struct fw_iso_context *context,
-				     dma_addr_t completed, void *data);
+typedef union {
+	void (*sc)(struct fw_iso_context *context, u32 cycle,
+		   size_t header_length, void *header, void *data);
+	void (*mc)(struct fw_iso_context *context, dma_addr_t completed,
+		   void *data);
+} __attribute__ ((__transparent_union__)) fw_iso_callback_t;
+
 struct fw_iso_context {
 	struct fw_card *card;
 	int type;
@@ -443,10 +445,7 @@ struct fw_iso_context {
 	int speed;
 	bool drop_overflow_headers;
 	size_t header_size;
-	union {
-		fw_iso_callback_t sc;
-		fw_iso_mc_callback_t mc;
-	} callback;
+	fw_iso_callback_t callback;
 	void *callback_data;
 };
 
-- 
2.27.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] firewire: fix function type cast warning
  2020-10-26 21:51 [PATCH] firewire: fix function type cast warning Arnd Bergmann
@ 2020-10-27  0:13 ` Takashi Sakamoto
  2020-10-27 12:48   ` Arnd Bergmann
  0 siblings, 1 reply; 3+ messages in thread
From: Takashi Sakamoto @ 2020-10-27  0:13 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Stefan Richter, linux1394-devel, Gustavo A. R. Silva,
	Arnd Bergmann, linux-kernel, oscar.carter

Hi Arnd,

On Mon, Oct 26, 2020 at 10:51:27PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> gcc -Wextra complains about a suspicious cast:
> 
> rivers/firewire/core-cdev.c:985:8: warning: cast between incompatible function types from ‘void (*)(struct fw_iso_context *, dma_addr_t,  void *)’ {aka ‘void (*)(struct fw_iso_context *, long long unsigned int,  void *)’} to ‘void (*)(struct fw_iso_context *, u32,  size_t,  void *, void *)’ {aka ‘void (*)(struct fw_iso_context *, unsigned int,  long unsigned int,  void *, void *)’} [-Wcast-function-type]
> 
> The behavior is correct in the end, but this is more clearly
> expressed using a transparent union.
> 
> Fixes: 872e330e3880 ("firewire: add isochronous multichannel reception")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/firewire/core-cdev.c |  6 +++---
>  drivers/firewire/core-iso.c  |  2 +-
>  include/linux/firewire.h     | 17 ++++++++---------
>  3 files changed, 12 insertions(+), 13 deletions(-)

Oscar Carter has posted a patch to fix it.
https://sourceforge.net/p/linux1394/mailman/message/37024966/

I don't know exactly but maintainers seems to overlook it...


Thanks

Takashi Sakamoto

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] firewire: fix function type cast warning
  2020-10-27  0:13 ` Takashi Sakamoto
@ 2020-10-27 12:48   ` Arnd Bergmann
  0 siblings, 0 replies; 3+ messages in thread
From: Arnd Bergmann @ 2020-10-27 12:48 UTC (permalink / raw)
  To: Arnd Bergmann, Stefan Richter, linux1394-devel,
	Gustavo A. R. Silva, Arnd Bergmann, linux-kernel, oscar.carter

On Tue, Oct 27, 2020 at 1:13 AM Takashi Sakamoto
<o-takashi@sakamocchi.jp> wrote:
> On Mon, Oct 26, 2020 at 10:51:27PM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > gcc -Wextra complains about a suspicious cast:
> >
> > rivers/firewire/core-cdev.c:985:8: warning: cast between incompatible function types from ‘void (*)(struct fw_iso_context *, dma_addr_t,  void *)’ {aka ‘void (*)(struct fw_iso_context *, long long unsigned int,  void *)’} to ‘void (*)(struct fw_iso_context *, u32,  size_t,  void *, void *)’ {aka ‘void (*)(struct fw_iso_context *, unsigned int,  long unsigned int,  void *, void *)’} [-Wcast-function-type]
> >
> > The behavior is correct in the end, but this is more clearly
> > expressed using a transparent union.
> >
> > Fixes: 872e330e3880 ("firewire: add isochronous multichannel reception")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  drivers/firewire/core-cdev.c |  6 +++---
> >  drivers/firewire/core-iso.c  |  2 +-
> >  include/linux/firewire.h     | 17 ++++++++---------
> >  3 files changed, 12 insertions(+), 13 deletions(-)
>
> Oscar Carter has posted a patch to fix it.
> https://sourceforge.net/p/linux1394/mailman/message/37024966/
>
> I don't know exactly but maintainers seems to overlook it...

Right, that seems fairly similar to my version but avoids the GNU
extension, so it would be better that version.

       Arnd

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-10-27 12:48 UTC | newest]

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2020-10-26 21:51 [PATCH] firewire: fix function type cast warning Arnd Bergmann
2020-10-27  0:13 ` Takashi Sakamoto
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