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

From: Petr Mladek
Date: Fri Dec 11 2015 - 08:21:20 EST


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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