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[4.19,3/6] mwifiex: Remove unnecessary braces from HostCmd_SET_SEQ_NO_BSS_INFO

Message ID 20211217144119.2538175-4-anders.roxell@linaro.org
State New
Headers show
Series fix warning and errors on arm built with clang | expand

Commit Message

Anders Roxell Dec. 17, 2021, 2:41 p.m. UTC
From: Nathan Chancellor <natechancellor@gmail.com>

commit 6a953dc4dbd1c7057fb765a24f37a5e953c85fb0 upstream.

A new warning in clang points out when macro expansion might result in a
GNU C statement expression. There is an instance of this in the mwifiex
driver:

drivers/net/wireless/marvell/mwifiex/cmdevt.c:217:34: warning: '}' and
')' tokens terminating statement expression appear in different macro
expansion contexts [-Wcompound-token-split-by-macro]
        host_cmd->seq_num = cpu_to_le16(HostCmd_SET_SEQ_NO_BSS_INFO
                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/marvell/mwifiex/fw.h:519:46: note: expanded from
macro 'HostCmd_SET_SEQ_NO_BSS_INFO'
        (((type) & 0x000f) << 12);                  }
                                                    ^

This does not appear to be a real issue. Removing the braces and
replacing them with parentheses will fix the warning and not change the
meaning of the code.

Fixes: 5e6e3a92b9a4 ("wireless: mwifiex: initial commit for Marvell mwifiex driver")
Link: https://github.com/ClangBuiltLinux/linux/issues/1146
Reported-by: Andy Lavr <andy.lavr@gmail.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 drivers/net/wireless/marvell/mwifiex/cmdevt.c | 4 ++--
 drivers/net/wireless/marvell/mwifiex/fw.h     | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

Comments

Greg KH Dec. 20, 2021, 10:56 a.m. UTC | #1
On Fri, Dec 17, 2021 at 03:41:16PM +0100, Anders Roxell wrote:
> From: Nathan Chancellor <natechancellor@gmail.com>
> 
> commit 6a953dc4dbd1c7057fb765a24f37a5e953c85fb0 upstream.
> 
> A new warning in clang points out when macro expansion might result in a
> GNU C statement expression. There is an instance of this in the mwifiex
> driver:
> 
> drivers/net/wireless/marvell/mwifiex/cmdevt.c:217:34: warning: '}' and
> ')' tokens terminating statement expression appear in different macro
> expansion contexts [-Wcompound-token-split-by-macro]
>         host_cmd->seq_num = cpu_to_le16(HostCmd_SET_SEQ_NO_BSS_INFO
>                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/wireless/marvell/mwifiex/fw.h:519:46: note: expanded from
> macro 'HostCmd_SET_SEQ_NO_BSS_INFO'
>         (((type) & 0x000f) << 12);                  }
>                                                     ^
> 
> This does not appear to be a real issue. Removing the braces and
> replacing them with parentheses will fix the warning and not change the
> meaning of the code.
> 
> Fixes: 5e6e3a92b9a4 ("wireless: mwifiex: initial commit for Marvell mwifiex driver")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1146
> Reported-by: Andy Lavr <andy.lavr@gmail.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---
>  drivers/net/wireless/marvell/mwifiex/cmdevt.c | 4 ++--
>  drivers/net/wireless/marvell/mwifiex/fw.h     | 8 ++++----
>  2 files changed, 6 insertions(+), 6 deletions(-)

Also needed in 5.4.y, right?
Joe Perches Dec. 20, 2021, 12:13 p.m. UTC | #2
On Fri, 2021-12-17 at 15:41 +0100, Anders Roxell wrote:
> From: Nathan Chancellor <natechancellor@gmail.com>
> 
> commit 6a953dc4dbd1c7057fb765a24f37a5e953c85fb0 upstream.
> 
> A new warning in clang points out when macro expansion might result in a
> GNU C statement expression. There is an instance of this in the mwifiex
> driver:
> 
> drivers/net/wireless/marvell/mwifiex/cmdevt.c:217:34: warning: '}' and
> ')' tokens terminating statement expression appear in different macro
> expansion contexts [-Wcompound-token-split-by-macro]
>         host_cmd->seq_num = cpu_to_le16(HostCmd_SET_SEQ_NO_BSS_INFO
>                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
[]
> diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
[]
> @@ -512,10 +512,10 @@ enum mwifiex_channel_flags {
>  
>  #define RF_ANTENNA_AUTO                 0xFFFF
>  
> -#define HostCmd_SET_SEQ_NO_BSS_INFO(seq, num, type) {   \
> -	(((seq) & 0x00ff) |                             \
> -	 (((num) & 0x000f) << 8)) |                     \
> -	(((type) & 0x000f) << 12);                  }
> +#define HostCmd_SET_SEQ_NO_BSS_INFO(seq, num, type) \
> +	((((seq) & 0x00ff) |                        \
> +	 (((num) & 0x000f) << 8)) |                 \
> +	(((type) & 0x000f) << 12))

Perhaps this would be better as a static inline

static inline u16 HostCmd_SET_SEQ_NO_BSS_INFO(u16 seq, u8 num, u8 type)
{
	return (type & 0x000f) << 12 | (num & 0x000f) << 8 | (seq & 0x00ff);
}
David Laight Dec. 20, 2021, 2 p.m. UTC | #3
From: Joe Perches
> Sent: 20 December 2021 12:13
> 
> On Fri, 2021-12-17 at 15:41 +0100, Anders Roxell wrote:
> > From: Nathan Chancellor <natechancellor@gmail.com>
> >
> > commit 6a953dc4dbd1c7057fb765a24f37a5e953c85fb0 upstream.
> >
> > A new warning in clang points out when macro expansion might result in a
> > GNU C statement expression. There is an instance of this in the mwifiex
> > driver:
> >
> > drivers/net/wireless/marvell/mwifiex/cmdevt.c:217:34: warning: '}' and
> > ')' tokens terminating statement expression appear in different macro
> > expansion contexts [-Wcompound-token-split-by-macro]
> >         host_cmd->seq_num = cpu_to_le16(HostCmd_SET_SEQ_NO_BSS_INFO
> >                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> []
> > diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
> []
> > @@ -512,10 +512,10 @@ enum mwifiex_channel_flags {
> >
> >  #define RF_ANTENNA_AUTO                 0xFFFF
> >
> > -#define HostCmd_SET_SEQ_NO_BSS_INFO(seq, num, type) {   \
> > -	(((seq) & 0x00ff) |                             \
> > -	 (((num) & 0x000f) << 8)) |                     \
> > -	(((type) & 0x000f) << 12);                  }
> > +#define HostCmd_SET_SEQ_NO_BSS_INFO(seq, num, type) \
> > +	((((seq) & 0x00ff) |                        \
> > +	 (((num) & 0x000f) << 8)) |                 \
> > +	(((type) & 0x000f) << 12))
> 
> Perhaps this would be better as a static inline
> 
> static inline u16 HostCmd_SET_SEQ_NO_BSS_INFO(u16 seq, u8 num, u8 type)
> {
> 	return (type & 0x000f) << 12 | (num & 0x000f) << 8 | (seq & 0x00ff);
> }

Just writing in on one line helps readability!
It is also used exactly twice, both with a cpu_to_le16().
I wonder how well the compiler handles that on BE?
The #define is more likely to be handled better.

I've only made a cursory glance at the code, but I get splitting
host_cmd->seq_num into two u8 fields would give better code!

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
diff mbox series

Patch

diff --git a/drivers/net/wireless/marvell/mwifiex/cmdevt.c b/drivers/net/wireless/marvell/mwifiex/cmdevt.c
index 60db2b969e20..b7ced103b814 100644
--- a/drivers/net/wireless/marvell/mwifiex/cmdevt.c
+++ b/drivers/net/wireless/marvell/mwifiex/cmdevt.c
@@ -324,9 +324,9 @@  static int mwifiex_dnld_sleep_confirm_cmd(struct mwifiex_adapter *adapter)
 
 	adapter->seq_num++;
 	sleep_cfm_buf->seq_num =
-		cpu_to_le16((HostCmd_SET_SEQ_NO_BSS_INFO
+		cpu_to_le16(HostCmd_SET_SEQ_NO_BSS_INFO
 					(adapter->seq_num, priv->bss_num,
-					 priv->bss_type)));
+					 priv->bss_type));
 
 	mwifiex_dbg(adapter, CMD,
 		    "cmd: DNLD_CMD: %#x, act %#x, len %d, seqno %#x\n",
diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
index 8b9d0809daf6..076ea1c4b921 100644
--- a/drivers/net/wireless/marvell/mwifiex/fw.h
+++ b/drivers/net/wireless/marvell/mwifiex/fw.h
@@ -512,10 +512,10 @@  enum mwifiex_channel_flags {
 
 #define RF_ANTENNA_AUTO                 0xFFFF
 
-#define HostCmd_SET_SEQ_NO_BSS_INFO(seq, num, type) {   \
-	(((seq) & 0x00ff) |                             \
-	 (((num) & 0x000f) << 8)) |                     \
-	(((type) & 0x000f) << 12);                  }
+#define HostCmd_SET_SEQ_NO_BSS_INFO(seq, num, type) \
+	((((seq) & 0x00ff) |                        \
+	 (((num) & 0x000f) << 8)) |                 \
+	(((type) & 0x000f) << 12))
 
 #define HostCmd_GET_SEQ_NO(seq)       \
 	((seq) & HostCmd_SEQ_NUM_MASK)