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From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 02/32] lib/vsprintf: implement bitmap printing through '%*pb[l]'
Date: Mon, 26 Jan 2015 14:50:05 +0100	[thread overview]
Message-ID: <20150126135005.GG23123@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1422108218-25398-3-git-send-email-tj@kernel.org>

On Sat, Jan 24, 2015 at 09:03:08AM -0500, Tejun Heo wrote:

> There have been a couple different attempts at making this easier.
> 
> 1. Way back, PeterZ tried printk '%pb' extension with the precision
>    for bit width - '%.*pb'.  This was intuitive and made sense but
>    unfortunately triggered a compile warning about using precision
>    for a pointer.
> 
>    http://lkml.kernel.org/g/1336577562.2527.58.camel@twins

> So, this patch is another attempt at teaching printk and friends how
> to print bitmaps.  It's almost identical to what PeterZ tried with
> precision but it uses the field width for the number of bits instead
> of precision.  The format used is '%*pb[l]', with the optional
> trailing 'l' specifying list format instead of hex masks.

> This is a valid format string and doesn't trigger compiler warnings;
> however, it does make it impossible to specify output field width when
> printing bitmaps.

> I think this is an acceptable trade-off given how
> much easier it makes printing bitmaps and that we don't have any
> in-kernel user which is using the field width specification.

Yeah, I suppose this is indeed the best we can do; and loosing the width
thing (which is a rarely used feature for in kernel things) seems
acceptable indeed. We did mention the option back then, but didn't
pursue it.

I like the extra 'l' fmt option.

> Signed-off-by: Tejun Heo <tj@kernel.org>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

  reply	other threads:[~2015-01-26 13:50 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-24 14:03 [PATCHSET] bitmap, cpumask, nodemask: implement %*pb[l] to format bitmaps directly from printf family of functions Tejun Heo
2015-01-24 14:03 ` [PATCH 01/32] cpumask: always use nr_cpu_ids in formatting and parsing functions Tejun Heo
2015-01-26 23:42   ` Rusty Russell
2015-01-24 14:03 ` [PATCH 02/32] lib/vsprintf: implement bitmap printing through '%*pb[l]' Tejun Heo
2015-01-26 13:50   ` Peter Zijlstra [this message]
2015-01-24 14:03 ` [PATCH 03/32] cpumask, nodemask: implement cpumask/nodemask_pr_args() Tejun Heo
2015-01-24 14:03 ` [PATCH 04/32] bitmap: use %*pb[l] to print bitmaps including cpumasks and nodemasks Tejun Heo
2015-01-24 14:03 ` [PATCH 05/32] mips: " Tejun Heo
2015-01-24 14:03 ` [PATCH 06/32] powerpc: " Tejun Heo
2015-01-24 14:03 ` [PATCH 07/32] s390: " Tejun Heo
2015-01-26  9:17   ` Heiko Carstens
2015-01-24 14:03 ` [PATCH 08/32] tile: " Tejun Heo
2015-01-24 14:03 ` [PATCH 09/32] x86: " Tejun Heo
2015-01-24 14:03 ` [PATCH 10/32] ia64: " Tejun Heo
2015-01-24 14:03 ` [PATCH 11/32] xtensa: " Tejun Heo
2015-01-24 14:03 ` [PATCH 12/32] arm: " Tejun Heo
2015-01-24 14:03 ` [PATCH 13/32] cpuset: " Tejun Heo
2015-01-24 14:03 ` [PATCH 14/32] rcu: " Tejun Heo
2015-01-24 21:16   ` Paul E. McKenney
2015-01-24 14:03 ` [PATCH 15/32] sched: " Tejun Heo
2015-01-24 14:03 ` [PATCH 16/32] time: " Tejun Heo
2015-01-24 14:03 ` [PATCH 17/32] percpu: " Tejun Heo
2015-01-24 14:03 ` [PATCH 18/32] workqueue: use %*pb[l] to format " Tejun Heo
2015-01-24 14:03 ` [PATCH 19/32] tracing: use %*pb[l] to print " Tejun Heo
2015-01-24 14:03 ` [PATCH 20/32] net: " Tejun Heo
2015-01-27  8:07   ` David Miller
2015-01-24 14:03 ` [PATCH 21/32] wireless: " Tejun Heo
2015-03-02 15:14   ` Kalle Valo
2015-01-24 14:03 ` [PATCH 22/32] input: " Tejun Heo
2015-01-24 14:03 ` [PATCH 23/32] scsi: " Tejun Heo
2015-01-24 14:03 ` [PATCH 24/32] usb: " Tejun Heo
2015-01-25 12:45   ` Greg Kroah-Hartman
2015-01-24 14:03 ` [PATCH 25/32] drivers/base: " Tejun Heo
2015-01-25 13:22   ` Greg Kroah-Hartman
2015-01-24 14:03 ` [PATCH 26/32] slub: " Tejun Heo
2015-01-24 17:48   ` Christoph Lameter
2015-01-24 14:03 ` [PATCH 27/32] mm: " Tejun Heo
2015-01-24 14:03 ` [PATCH 28/32] padata: " Tejun Heo
2015-01-24 14:03 ` [PATCH 29/32] proc: " Tejun Heo
2015-01-24 14:03 ` [PATCH 30/32] irq: " Tejun Heo
2015-01-24 14:03 ` [PATCH 31/32] profile: " Tejun Heo
2015-01-24 14:03 ` [PATCH 32/32] bitmap, cpumask, nodemask: remove dedicated formatting functions Tejun Heo

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