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| 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 /include/trace | |
| parent | 1310051c720a83c5717658bcbff710b260f2bff9 (diff) | |
| download | linux-05eb06d86685e7d9dac60e6bbb46d7f4c30b056e.tar.gz linux-05eb06d86685e7d9dac60e6bbb46d7f4c30b056e.tar.bz2 linux-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 'include/trace')
| -rw-r--r-- | include/trace/events/rpcrdma.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/include/trace/events/rpcrdma.h b/include/trace/events/rpcrdma.h index 59492a93fe1d..2fb415136f7b 100644 --- a/include/trace/events/rpcrdma.h +++ b/include/trace/events/rpcrdma.h @@ -539,6 +539,33 @@ TRACE_EVENT(xprtrdma_marshal_failed, ) ); +TRACE_EVENT(xprtrdma_prepsend_failed, + TP_PROTO(const struct rpc_rqst *rqst, + int ret + ), + + TP_ARGS(rqst, ret), + + TP_STRUCT__entry( + __field(unsigned int, task_id) + __field(unsigned int, client_id) + __field(u32, xid) + __field(int, ret) + ), + + TP_fast_assign( + __entry->task_id = rqst->rq_task->tk_pid; + __entry->client_id = rqst->rq_task->tk_client->cl_clid; + __entry->xid = be32_to_cpu(rqst->rq_xid); + __entry->ret = ret; + ), + + TP_printk("task:%u@%u xid=0x%08x: ret=%d", + __entry->task_id, __entry->client_id, __entry->xid, + __entry->ret + ) +); + TRACE_EVENT(xprtrdma_post_send, TP_PROTO( const struct rpcrdma_req *req, |