linux-kernel - Re: [PATCH v3 1/4] kdb: Re-factor kdb

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Date:   Wed, 27 May 2020 09:29:07 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Sumit Garg <sumit.garg@...aro.org>
Cc:     kgdb-bugreport@...ts.sourceforge.net, jason.wessel@...driver.com,
        dianders@...omium.org, pmladek@...e.com,
        sergey.senozhatsky@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/4] kdb: Re-factor kdb_printf() message write code

On Wed, May 27, 2020 at 11:55:56AM +0530, Sumit Garg wrote:
> Re-factor kdb_printf() message write code in order to avoid duplication
> of code and thereby increase readability.
> 
> Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
> ---
>  kernel/debug/kdb/kdb_io.c | 61 +++++++++++++++++++++++++----------------------
>  1 file changed, 32 insertions(+), 29 deletions(-)
> 
> diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
> index 924bc92..f6b4d47 100644
> --- a/kernel/debug/kdb/kdb_io.c
> +++ b/kernel/debug/kdb/kdb_io.c
> @@ -542,6 +542,33 @@ static int kdb_search_string(char *searched, char *searchfor)
>  	return 0;
>  }
>  
> +static void kdb_io_write(char *cp, int len, void (*io_put_char)(u8 ch))

Don't use a function pointer here. Just pick it up from dbg_io_ops as
usual.


> +{
> +	if (len <= 0)
> +		return;

How can len ever be negative?


> +
> +	while (len--) {
> +		io_put_char(*cp);
> +		cp++;
> +	}
> +}
> +
> +static void kdb_msg_write(char *msg, int msg_len)
> +{
> +	struct console *c;
> +
> +	if (msg_len <= 0)
> +		return;

How can msg_len ever be negative?


> +
> +	if (dbg_io_ops && !dbg_io_ops->is_console)
> +		kdb_io_write(msg, msg_len, dbg_io_ops->write_char);
> +
> +	for_each_console(c) {
> +		c->write(c, msg, msg_len);
> +		touch_nmi_watchdog();
> +	}
> +}
> +
>  int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
>  {
>  	int diag;
> @@ -553,7 +580,6 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
>  	int this_cpu, old_cpu;
>  	char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
>  	char *moreprompt = "more> ";
> -	struct console *c;
>  	unsigned long uninitialized_var(flags);
>  
>  	/* Serialize kdb_printf if multiple cpus try to write at once.
> @@ -687,22 +713,11 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
>  	 */
>  	retlen = strlen(kdb_buffer);
>  	cp = (char *) printk_skip_headers(kdb_buffer);
> -	if (!dbg_kdb_mode && kgdb_connected) {
> +	if (!dbg_kdb_mode && kgdb_connected)
>  		gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
> -	} else {
> -		if (dbg_io_ops && !dbg_io_ops->is_console) {
> -			len = retlen - (cp - kdb_buffer);
> -			cp2 = cp;
> -			while (len--) {
> -				dbg_io_ops->write_char(*cp2);
> -				cp2++;
> -			}
> -		}
> -		for_each_console(c) {
> -			c->write(c, cp, retlen - (cp - kdb_buffer));
> -			touch_nmi_watchdog();
> -		}
> -	}
> +	else
> +		kdb_msg_write(cp, retlen - (cp - kdb_buffer));
> +
>  	if (logging) {
>  		saved_loglevel = console_loglevel;
>  		console_loglevel = CONSOLE_LOGLEVEL_SILENT;
> @@ -751,19 +766,7 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
>  			moreprompt = "more> ";
>  
>  		kdb_input_flush();
> -
> -		if (dbg_io_ops && !dbg_io_ops->is_console) {
> -			len = strlen(moreprompt);
> -			cp = moreprompt;
> -			while (len--) {
> -				dbg_io_ops->write_char(*cp);
> -				cp++;
> -			}
> -		}
> -		for_each_console(c) {
> -			c->write(c, moreprompt, strlen(moreprompt));
> -			touch_nmi_watchdog();
> -		}
> +		kdb_msg_write(moreprompt, strlen(moreprompt));
>  
>  		if (logging)
>  			printk("%s", moreprompt);
> -- 
> 2.7.4
>