In the current kernel, percpu variable `vector_irq' is not always
cleared when a CPU is offlined. If the CPU that has the disabled
irqs in vector_irq is hotplugged again, __setup_vector_irq()
hits invalid irq vector and may crash.
This bug can be reproduced as following;
# echo 0 > /sys/devices/system/cpu/cpu7/online
# modprobe -r some_driver_using_interrupts # vector_irq@cpu7 uncleared
# echo 1 > /sys/devices/system/cpu/cpu7/online # kernel may crash
To fix this problem, this patch clears vector_irq in
__fixup_irqs() when the CPU is offlined.
This also reverts commit f6175f5bfb, which partially fixes
this bug by clearing vector in __clear_irq_vector(). But in
environments with IOMMU IRQ remapper, it could fail because
cfg->domain doesn't contain offlined CPUs. With this patch, the
fix in __clear_irq_vector() can be reverted because every
vector_irq is already cleared in __fixup_irqs() on offlined CPUs.
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/20120726104732.2889.19144.stgit@kvmdev
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1d44b30f35