diff options
| author |   Chuck Lever <chuck.lever@oracle.com> | 2019-06-19 10:32:48 -0400 |
|---|---|---|
| committer |   Anna Schumaker <Anna.Schumaker@Netapp.com> | 2019-07-09 10:30:16 -0400 |
| commit | 05eb06d86685e7d9dac60e6bbb46d7f4c30b056e (patch) | |
| tree | 8f04bce3b88e16afd6912e44681b80752721c171 /net/sunrpc/xprtrdma/transport.c | |
| parent | xprtrdma: Replace use of xdr_stream_pos in rpcrdma_marshal_req (diff) | |
| download | linux-dev-05eb06d86685e7d9dac60e6bbb46d7f4c30b056e.tar.xz linux-dev-05eb06d86685e7d9dac60e6bbb46d7f4c30b056e.zip | |
xprtrdma: Fix occasional transport deadlock
Under high I/O workloads, I've noticed that an RPC/RDMA transport
occasionally deadlocks (IOPS goes to zero, and doesn't recover).
Diagnosis shows that the sendctx queue is empty, but when sendctxs
are returned to the queue, the xprt_write_space wake-up never
occurs. The wake-up logic in rpcrdma_sendctx_put_locked is racy.
I noticed that both EMPTY_SCQ and XPRT_WRITE_SPACE are implemented
via an atomic bit. Just one of those is sufficient. Removing
EMPTY_SCQ in favor of the generic bit mechanism makes the deadlock
un-reproducible.
Without EMPTY_SCQ, rpcrdma_buffer::rb_flags is no longer used and
is therefore removed.
Unfortunately this patch does not apply cleanly to stable. If
needed, someone will have to port it and test it.
Fixes: 2fad659209d5 ("xprtrdma: Wait on empty sendctx queue")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc/xprtrdma/transport.c')
0 files changed, 0 insertions, 0 deletions