linux-kernel - Re: [tip: timers/core] timer_list: Use printk format instead of open-coded symbol lookup

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Message-ID: <720b8857ebbe1be81babd04463b865d94049c0a9.camel@perches.com>
Date:   Sun, 15 Nov 2020 17:48:01 -0800
From:   Joe Perches <joe@...ches.com>
To:     linux-kernel@...r.kernel.org, linux-tip-commits@...r.kernel.org
Cc:     Helge Deller <deller@....de>, Thomas Gleixner <tglx@...utronix.de>,
        x86@...nel.org
Subject: Re: [tip: timers/core] timer_list: Use printk format instead of
 open-coded symbol lookup

On Sun, 2020-11-15 at 22:51 +0000, tip-bot2 for Helge Deller wrote:
> The following commit has been merged into the timers/core branch of tip:
> 
> Commit-ID:     da88f9b3113620dcd30fc203236aa53d5430ee98
> Gitweb:        https://git.kernel.org/tip/da88f9b3113620dcd30fc203236aa53d5430ee98
> Author:        Helge Deller <deller@....de>
> AuthorDate:    Wed, 04 Nov 2020 17:34:01 +01:00
> Committer:     Thomas Gleixner <tglx@...utronix.de>
> CommitterDate: Sun, 15 Nov 2020 20:47:14 +01:00
> 
> timer_list: Use printk format instead of open-coded symbol lookup
> 
> Use the "%ps" printk format string to resolve symbol names.
> 
> This works on all platforms, including ia64, ppc64 and parisc64 on which
> one needs to dereference pointers to function descriptors instead of
> function pointers.
> 
> Signed-off-by: Helge Deller <deller@....de>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Link: https://lore.kernel.org/r/20201104163401.GA3984@ls3530.fritz.box
> 
> 
> ---
>  kernel/time/timer_list.c | 66 +++++++++++----------------------------
>  1 file changed, 19 insertions(+), 47 deletions(-)
> 
> diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
> index acb326f..6939140 100644
> --- a/kernel/time/timer_list.c
> +++ b/kernel/time/timer_list.c
> @@ -42,24 +42,11 @@ static void SEQ_printf(struct seq_file *m, const char *fmt, ...)
>  	va_end(args);
>  }
>  
> 
> -static void print_name_offset(struct seq_file *m, void *sym)
> -{
> -	char symname[KSYM_NAME_LEN];
> -
> -	if (lookup_symbol_name((unsigned long)sym, symname) < 0)
> -		SEQ_printf(m, "<%pK>", sym);
> -	else
> -		SEQ_printf(m, "%s", symname);
> -}
> -
>  static void
>  print_timer(struct seq_file *m, struct hrtimer *taddr, struct hrtimer *timer,
>  	    int idx, u64 now)
>  {
> -	SEQ_printf(m, " #%d: ", idx);
> -	print_name_offset(m, taddr);
> -	SEQ_printf(m, ", ");
> -	print_name_offset(m, timer->function);
> +	SEQ_printf(m, " #%d: <%pK>, %ps", idx, taddr, timer->function);
>  	SEQ_printf(m, ", S:%02x", timer->state);
>  	SEQ_printf(m, "\n");

trivia:

This could be coalesced into a single line statement.

	SEQ_printf(m, "%d: <%pK>, %ps, S:%02x\n",
		   idx, taddr, timer->function, timer->state);

[]

> -	if (dev->set_state_periodic) {
> -		SEQ_printf(m, " periodic: ");
> -		print_name_offset(m, dev->set_state_periodic);
> -		SEQ_printf(m, "\n");
> -	}
> +	if (dev->set_state_periodic)
> +		SEQ_printf(m, " periodic:       %ps\n",
> +			dev->set_state_periodic);

There is now additional whitespace after periodic: and oneshot:

This _might_ break some silly script that uses fixed column alignment
for the SEQ_ output.

It does look nicer now though.