linux-kernel - Re: [PATCH 1/1] printk: add __printf attributes to internal functions

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Date:   Mon, 22 May 2017 17:22:11 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Nicolas Iooss <nicolas.iooss_linux@....org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] printk: add __printf attributes to internal functions

On Sat 2017-05-20 11:18:53, Nicolas Iooss wrote:
> When compiling with -Wsuggest-attribute=format, gcc complains that some
> functions in kernel/printk/printk_safe.c transmit their argument to
> printf-like functions without having a printf attribute. Silence these
> warnings by adding relevant __printf attributes.
> 
> Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@....org>
> ---
>  kernel/printk/printk_safe.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
> index 033e50a7d706..2e27a31941f4 100644
> --- a/kernel/printk/printk_safe.c
> +++ b/kernel/printk/printk_safe.c
> @@ -80,8 +80,8 @@ static void queue_flush_work(struct printk_safe_seq_buf *s)
>   * happen, printk_safe_log_store() will notice the buffer->len mismatch
>   * and repeat the write.
>   */
> -static int printk_safe_log_store(struct printk_safe_seq_buf *s,
> -				 const char *fmt, va_list args)
> +static __printf(2, 0) int printk_safe_log_store(struct printk_safe_seq_buf *s,
> +						const char *fmt, va_list args)
>  {
>  	int add;
>  	size_t len;
> @@ -299,7 +299,7 @@ void printk_safe_flush_on_panic(void)
>   * one writer running. But the buffer might get flushed from another
>   * CPU, so we need to be careful.
>   */
> -static int vprintk_nmi(const char *fmt, va_list args)
> +static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args)

There is one more variant of this function used when CONFIG_PRINTK_NMI
is not defined. Feel free to send updated patch as a reply. Or I could
add this trivial change when pushing this patch to printk.git if nobody
complains.

Otherwise, the patch looks fine to me. Therefore with patching the other
vprintk_nmi() variant:

Acked-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr