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e5248a7426
Threads parked in svc_rdma_sq_wait() on sc_sq_ticket_wait or
sc_send_wait can hang indefinitely in TASK_UNINTERRUPTIBLE state
across transport teardown, pinning svc_xprt references and
blocking svc_rdma_free().
The close path sets XPT_CLOSE before invoking xpo_detach and both
wait_event predicates include an XPT_CLOSE term, but the
predicates are re-evaluated only on wakeup. sc_sq_ticket_wait has
no completion-driven wake path; it is advanced solely by the
chained ticket handoff inside svc_rdma_sq_wait() itself. Without
an explicit wake at close, parked threads never observe
XPT_CLOSE, hold their svc_xprt_get reference forever, and
svc_rdma_free() blocks on xpt_ref dropping to zero.
Two close entry points reach this transport. Local teardown runs
svc_rdma_detach() from svc_handle_xprt() -> svc_delete_xprt() ->
xpo_detach() on a worker thread. A remote disconnect arrives at
svc_rdma_cma_handler(), which calls svc_xprt_deferred_close():
that sets XPT_CLOSE and enqueues the transport but does not
access either RDMA waitqueue, so a worker already parked in
svc_rdma_sq_wait() never re-evaluates its predicate. With every
worker parked on this transport, no thread is available to run
the local teardown either, and the wake site there is
unreachable.
Introduce svc_rdma_xprt_deferred_close(), a thin svcrdma wrapper
that calls svc_xprt_deferred_close() and then wakes both
sc_sq_ticket_wait and sc_send_wait. Convert the svcrdma producers
that called svc_xprt_deferred_close() directly:
svc_rdma_cma_handler(), qp_event_handler(),
svc_rdma_post_send_err(), svc_rdma_wc_send(), the sendto drop
path, the rw completion error paths, and the recvfrom flush and
read-list error paths.
Wake both waitqueues from svc_rdma_detach() as well. The
synchronous svc_xprt_close() path (backchannel ENOTCONN, device
removal via svc_rdma_xprt_done) reaches detach without flowing
through svc_xprt_deferred_close() and therefore does not invoke
the new helper.
Fixes:
|
||
|---|---|---|
| .. | ||
| xdrgen | ||
| addr.h | ||
| auth_gss.h | ||
| auth.h | ||
| bc_xprt.h | ||
| cache.h | ||
| clnt.h | ||
| debug.h | ||
| gss_api.h | ||
| gss_err.h | ||
| gss_krb5.h | ||
| metrics.h | ||
| msg_prot.h | ||
| rdma_rn.h | ||
| rpc_pipe_fs.h | ||
| rpc_rdma_cid.h | ||
| rpc_rdma.h | ||
| sched.h | ||
| stats.h | ||
| svc_rdma_pcl.h | ||
| svc_rdma.h | ||
| svc_xprt.h | ||
| svc.h | ||
| svcauth_gss.h | ||
| svcauth.h | ||
| svcsock.h | ||
| timer.h | ||
| types.h | ||
| xdr.h | ||
| xprt.h | ||
| xprtmultipath.h | ||
| xprtrdma.h | ||
| xprtsock.h | ||