b4a4957d3d
rvt_destroy_qp() cannot complete until all in process packets have
been released from the underlying hardware. If a link down event
occurs, an application can hang with a kernel stack similar to:
cat /proc/<app PID>/stack
quiesce_qp+0x178/0x250 [hfi1]
rvt_reset_qp+0x23d/0x400 [rdmavt]
rvt_destroy_qp+0x69/0x210 [rdmavt]
ib_destroy_qp+0xba/0x1c0 [ib_core]
nvme_rdma_destroy_queue_ib+0x46/0x80 [nvme_rdma]
nvme_rdma_free_queue+0x3c/0xd0 [nvme_rdma]
nvme_rdma_destroy_io_queues+0x88/0xd0 [nvme_rdma]
nvme_rdma_error_recovery_work+0x52/0xf0 [nvme_rdma]
process_one_work+0x17a/0x440
worker_thread+0x126/0x3c0
kthread+0xcf/0xe0
ret_from_fork+0x58/0x90
0xffffffffffffffff
quiesce_qp() waits until all outstanding packets have been freed.
This wait should be momentary. During a link down event, the cleanup
handling does not ensure that all packets caught by the link down are
flushed properly.
This is caused by the fact that the freeze path and the link down
event is handled the same. This is not correct. The freeze path
waits until the HFI is unfrozen and then restarts PIO. A link down
is not a freeze event. The link down path cannot restart the PIO
until link is restored. If the PIO path is restarted before the link
comes up, the application (QP) using the PIO path will hang (until
link is restored).
Fix by separating the linkdown path from the freeze path and use the
link down path for link down events.
Close a race condition sc_disable() by acquiring both the progress
and release locks.
Close a race condition in sc_stop() by moving the setting of the flag
bits under the alloc lock.
Cc: <stable@vger.kernel.org> # 4.9.x+
Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
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
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In order to build the documentation, use ``make htmldocs`` or
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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.