Re: [PATCH] seq_buf: make DECLARE_SEQ_BUF() usable

[Steven Rostedt]

Kees,

Are you OK with this change? I ran it through my tests and have another
pull request ready to go that includes this. But I don't want to send it
without an Acked-by from you.

Luckily, Linus is on non-voluntary vacation so we may still have time ;-)

-- Steve


On Tue, 16 Jan 2024 08:09:25 -0600
Nathan Lynch via B4 Relay <devnull+nathanl.linux.ibm.com@xxxxxxxxxx> wrote:

> From: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
> 
> Using the address operator on the array doesn't work:
> 
> ./include/linux/seq_buf.h:27:27: error: initialization of ‘char *’
>   from incompatible pointer type ‘char (*)[128]’
>   [-Werror=incompatible-pointer-types]
>    27 |                 .buffer = &__ ## NAME ## _buffer,       \
>       |                           ^
> 
> Apart from fixing that, we can improve DECLARE_SEQ_BUF() by using a
> compound literal to define the buffer array without attaching a name
> to it. This makes the macro a single statement, allowing constructs
> such as:
> 
>   static DECLARE_SEQ_BUF(my_seq_buf, MYSB_SIZE);
> 
> to work as intended.
> 
> Signed-off-by: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
> Fixes: dcc4e5728eea ("seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()")
> ---
>  include/linux/seq_buf.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> index 5fb1f12c33f9..c44f4b47b945 100644
> --- a/include/linux/seq_buf.h
> +++ b/include/linux/seq_buf.h
> @@ -22,9 +22,8 @@ struct seq_buf {
>  };
>  
>  #define DECLARE_SEQ_BUF(NAME, SIZE)			\
> -	char __ ## NAME ## _buffer[SIZE] = "";		\
>  	struct seq_buf NAME = {				\
> -		.buffer = &__ ## NAME ## _buffer,	\
> +		.buffer = (char[SIZE]) { 0 },		\
>  		.size = SIZE,				\
>  	}
>  
> 
> ---
> base-commit: 70d201a40823acba23899342d62bc2644051ad2e
> change-id: 20240112-declare-seq-buf-fix-9803b7e679bc
> 
> Best regards,