[PATCH v2 0/3] introduce update_irq_devid and optimize VFIO irq ops

[Ben Luo <luoben@linux.alibaba.com>]

Currently, VFIO takes a lot of free-then-request-irq actions whenever
a VM (with device passthru via VFIO) sets irq affinity or mask/unmask
irq. Those actions only change the cookie data of irqaction or even
change nothing. The free-then-request-irq not only add more latency,
but also increases the risk of losing interrupt, this may lead to a
VM hung forever in waiting IO completion

This patchset solved this issue by:
Patch 2 introduces update_irq_devid to only update dev_id of irqaction
Patch 3 make use of update_irq_devid and optimize irq operations in VFIO

changes from v1:
 - add Patch 1 to enhance error recovery etc. in free irq per tglx's comments
 - enhance error recovery code and debugging info in update_irq_devid
 - use __must_check in external referencing of update_irq_devid
 - use EXPORT_SYMBOL_GPL for update_irq_devid
 - reformat code of patch 3 for better readability

Ben Luo (3):
  genirq: enhance error recovery code in free irq
  genirq: introduce update_irq_devid()
  vfio_pci: make use of update_irq_devid and optimize irq ops

 drivers/vfio/pci/vfio_pci_intrs.c |  99 +++++++++++++++++++++-------------
 include/linux/interrupt.h         |   3 ++
 kernel/irq/manage.c               | 111 +++++++++++++++++++++++++++++++++-----
 3 files changed, 163 insertions(+), 50 deletions(-)

-- 
1.8.3.1