linux-kernel - [PATCH v4 0/4] Cleaning printk stuff in NMI context

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Date:	Fri, 11 Dec 2015 14:20:48 +0100
From:	Petr Mladek <pmladek@...e.com>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Arnd Bergmann <arnd@...db.de>, jkosina@...e.com,
	pmladek@...e.com
Subject: [PATCH v4 0/4] Cleaning printk stuff in NMI context

Hi Andrew,

this is just a quick respin of the previous version. It changes
the few details as you suggested. Also it fixes the build problem
on ARM as reported by Geert and Arnd.

I rather send the whole patch set because there is the renamed header.
Also the extra blank space affects two patches. I hope that it will
safe you some work. Please, let me know if you would prefer
incremental patches.


Changes against v3:

  + used size_t for "len" and "size"

  + replaced WARN() with pr_err()

  + renamed kernel/printk/printk.h -> internal.h

  + fixed build on ARM (undefined NMI_LOG_BUF_SHIFT)


Changes against v2:

  + fixed compilation problems reported by 0-day build robot

  + MN10300 and Xtensa architectures will get handled separately

  + dropped the patch that printed NMI messages directly when Oops
    in progress; it made the solution less reliable

  + made the size of the buffer configurable; use real numbers
    instead of PAGE_SIZE


Changes against v1:

  + rebased on top of 4.4-rc2; there the old implementation was
    moved to lib/nmi_backtrace.c and used also on arm; I hope that
    I got the arm side correctly; I was not able to test on arm :-(

  + defined HAVE_NMI on arm for !CPU_V7M instead of !CPU_V7;
    handle_fiq_as_nmi() is called from entry-armv.S that
    is compiled when !CPU_V7M

  + defined HAVE_NMI also on mips; it calls nmi_enter() and
    seems to have real NMIs (or am I wrong?)

  + serialized backtraces when printing directly
    (oops_in_progress)


Petr Mladek (4):
  printk/nmi: Generic solution for safe printk in NMI
  printk/nmi: Use IRQ work only when ready
  printk/nmi: Warn when some message has been lost in NMI context
  printk/nmi: Increase the size of NMI buffer and make it configurable

 arch/Kconfig                  |   7 ++
 arch/arm/Kconfig              |   2 +
 arch/arm/kernel/smp.c         |   2 +
 arch/avr32/Kconfig            |   1 +
 arch/blackfin/Kconfig         |   1 +
 arch/cris/Kconfig             |   1 +
 arch/mips/Kconfig             |   1 +
 arch/powerpc/Kconfig          |   1 +
 arch/s390/Kconfig             |   1 +
 arch/sh/Kconfig               |   1 +
 arch/sparc/Kconfig            |   1 +
 arch/tile/Kconfig             |   1 +
 arch/x86/Kconfig              |   1 +
 arch/x86/kernel/apic/hw_nmi.c |   1 -
 include/linux/hardirq.h       |   2 +
 include/linux/percpu.h        |   3 -
 include/linux/printk.h        |  12 ++-
 init/Kconfig                  |  27 +++++
 init/main.c                   |   1 +
 kernel/printk/Makefile        |   1 +
 kernel/printk/internal.h      |  55 +++++++++++
 kernel/printk/nmi.c           | 222 ++++++++++++++++++++++++++++++++++++++++++
 kernel/printk/printk.c        |  29 +++---
 lib/nmi_backtrace.c           |  89 +----------------
 24 files changed, 356 insertions(+), 107 deletions(-)
 create mode 100644 kernel/printk/internal.h
 create mode 100644 kernel/printk/nmi.c

-- 
1.8.5.6

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