[PATCH V2 0/5] blk-mq: wait until completed req's complete fn is run

[ming.lei@redhat.com (Ming Lei)]

Hi,

blk-mq may schedule to call queue's complete function on remote CPU via
IPI, but never provide any way to synchronize the request's complete
fn.

In some driver's EH(such as NVMe), hardware queue's resource may be freed &
re-allocated. If the completed request's complete fn is run finally after the
hardware queue's resource is released, kernel crash will be triggered.

Fixes this issue by waitting until completed req's complete fn is run.

V2:
	- fix one build warning
	- fix commit log
	- apply the wait on nvme-fc code too

Thanks,
Ming

Ming Lei (5):
  blk-mq: introduce blk_mq_request_completed()
  blk-mq: introduce blk_mq_tagset_wait_completed_request()
  nvme: don't abort completed request in nvme_cancel_request
  nvme: wait until all completed request's complete fn is called
  blk-mq: remove blk_mq_complete_request_sync

 block/blk-mq-tag.c         | 32 ++++++++++++++++++++++++++++++++
 block/blk-mq.c             | 13 ++++++-------
 drivers/nvme/host/core.c   |  6 +++++-
 drivers/nvme/host/fc.c     |  2 ++
 drivers/nvme/host/pci.c    |  2 ++
 drivers/nvme/host/rdma.c   |  8 ++++++--
 drivers/nvme/host/tcp.c    |  8 ++++++--
 drivers/nvme/target/loop.c |  2 ++
 include/linux/blk-mq.h     |  3 ++-
 9 files changed, 63 insertions(+), 13 deletions(-)

Cc: Max Gurtovoy <maxg at mellanox.com>
Cc: Sagi Grimberg <sagi at grimberg.me>
Cc: Keith Busch <keith.busch at intel.com>
Cc: Christoph Hellwig <hch at lst.de>

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2.20.1