linux/arch/powerpc
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
..
boot Merge branch 'topic/kbuild' into next 2018-06-03 20:24:15 +10:00
configs powerpc/config: powernv_defconfig updates 2018-05-10 23:25:07 +10:00
crypto crypto: hash - annotate algorithms taking optional key 2018-01-12 23:03:35 +11:00
include Merge branch 'topic/pkey' into next 2018-06-03 20:35:27 +10:00
kernel powerpc/64: irq_work avoid interrupt when called with hardware irqs enabled 2018-06-03 20:40:25 +10:00
kvm Merge branch 'topic/ppc-kvm' into next 2018-05-15 22:28:19 +10:00
lib powerpc/altivec: Add missing prototypes for altivec 2018-05-25 12:04:38 +10:00
math-emu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mm powerpc: Fix build by disabling attribute-alias warning for SYSCALL_DEFINEx 2018-06-03 20:40:24 +10:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-05 11:29:24 -08:00
oprofile powerpc: Use sizeof(*foo) rather than sizeof(struct foo) 2018-03-20 16:47:53 +11:00
perf powerpc/perf: Update raw-event code encoding comment for power8 2018-05-25 17:49:01 +10:00
platforms powerpc/powernv/ioda2: Remove redundant free of TCE pages 2018-06-03 20:40:25 +10:00
purgatory License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sysdev powerpc/xive: prepare all hcalls to support long busy delays 2018-05-10 23:25:10 +10:00
tools powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS 2018-06-01 23:08:09 +10:00
xmon powerpc/xmon: use match_string() helper 2018-06-03 20:40:24 +10:00
Kconfig powerpc/livepatch: Implement reliable stack tracing for the consistency model 2018-05-10 23:25:12 +10:00
Kconfig.debug powerpc: Add new kconfig CONFIG_PPC_IRQ_SOFT_MASK_DEBUG 2018-01-19 22:37:03 +11:00
Makefile powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS 2018-06-01 23:08:09 +10:00
Makefile.postlink License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00