linux-kernel - [PATCH 0/4] lib/vsprintf: Remove atomic-unsafe support for printk format %pCr

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Date:   Fri,  1 Jun 2018 11:28:18 +0200
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Jia-Ju Bai <baijiaju1990@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Eric Anholt <eric@...olt.net>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-doc@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 0/4] lib/vsprintf: Remove atomic-unsafe support for printk format %pCr

	Hi all,

"%pCr" formats the current rate of a clock, and calls clk_get_rate().
The latter obtains a mutex, hence it must not be called from atomic
context.  As vsprintf() (and e.g. printk()) must be callable from any
context, it's better to remove support for this (rarely-used) format.

This patch series:
  - Changes all existing users of "%pCr" to print the result of
    clk_get_rate() directly, which is safe as they all do this in task
    context only,
  - Removes support for the "%pCr" printk format.

Note that any remaining out-of-tree users will start seeing the clock's
name printed instead of its rate.

Thanks for your comments!

Geert Uytterhoeven (4):
  clk: renesas: cpg-mssr: Stop using printk format %pCr
  thermal: bcm2835: Stop using printk format %pCr
  serial: sh-sci: Stop using printk format %pCr
  lib/vsprintf: Remove atomic-unsafe support for %pCr

 Documentation/core-api/printk-formats.rst  | 3 +--
 drivers/clk/renesas/renesas-cpg-mssr.c     | 9 +++++----
 drivers/thermal/broadcom/bcm2835_thermal.c | 4 ++--
 drivers/tty/serial/sh-sci.c                | 4 ++--
 lib/vsprintf.c                             | 3 ---
 5 files changed, 10 insertions(+), 13 deletions(-)

-- 
2.7.4

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds