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Nicholas Piggin ebb37cf3ff powerpc/64: irq_work avoid interrupt when called with hardware irqs enabled
irq_work_raise should not cause a decrementer exception unless it is
called from NMI context. Doing so often just results in an immediate
masked decrementer interrupt:

   <...>-550    90d...    4us : update_curr_rt <-dequeue_task_rt
   <...>-550    90d...    5us : dbs_update_util_handler <-update_curr_rt
   <...>-550    90d...    6us : arch_irq_work_raise <-irq_work_queue
   <...>-550    90d...    7us : soft_nmi_interrupt <-soft_nmi_common
   <...>-550    90d...    7us : printk_nmi_enter <-soft_nmi_interrupt
   <...>-550    90d.Z.    8us : rcu_nmi_enter <-soft_nmi_interrupt
   <...>-550    90d.Z.    9us : rcu_nmi_exit <-soft_nmi_interrupt
   <...>-550    90d...    9us : printk_nmi_exit <-soft_nmi_interrupt
   <...>-550    90d...   10us : cpuacct_charge <-update_curr_rt

The soft_nmi_interrupt here is the call into the watchdog, due to the
decrementer interrupt firing with irqs soft-disabled. This is
harmless, but sub-optimal.

When it's not called from NMI context or with interrupts enabled, mark
the decrementer pending in the irq_happened mask directly, rather than
having the masked decrementer interupt handler do it. This will be
replayed at the next local_irq_enable. See the comment for details.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-06-03 20:40:25 +10:00
arch powerpc/64: irq_work avoid interrupt when called with hardware irqs enabled 2018-06-03 20:40:25 +10:00
block
certs
crypto
Documentation Merge branch 'fixes' into next 2018-06-03 20:32:02 +10:00
drivers Merge branch 'fixes' into next 2018-06-03 20:32:02 +10:00
firmware
fs mm/pkeys, x86, powerpc: Display pkey in smaps if arch supports pkeys 2018-05-09 11:51:49 +10:00
include mm/pkeys: Add an empty arch_pkeys_enabled() 2018-05-09 11:51:46 +10:00
init
ipc
kernel powerpc/syscalls: switch rtas(2) to SYSCALL_DEFINE 2018-05-10 23:25:14 +10:00
lib Driver core fixes for 4.17-rc3 2018-04-27 10:12:20 -07:00
LICENSES
mm
net A CephFS quota follow-up and fixes for two older issues in the 2018-04-27 10:56:29 -07:00
samples
scripts powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS 2018-06-01 23:08:09 +10:00
security
sound
tools selftests/powerpc: Add core file test for Protection Key registers 2018-05-28 18:46:36 +10:00
usr
virt KVM fixes for v4.17-rc3 2018-04-27 16:13:31 -07:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
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MAINTAINERS MAINTAINERS: add myself as maintainer of AFFS 2018-04-28 10:30:47 -07:00
Makefile Linux v4.17-rc3 2018-04-29 14:17:42 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.