From cf657269d311d575eb196c7045579b3443631b8b Mon Sep 17 00:00:00 2001 From: Santosh Shilimkar Date: Thu, 29 Sep 2016 11:07:11 -0700 Subject: [PATCH] RDS: IB: fix panic due to handlers running post teardown Shutdown code reaping loop takes care of emptying the CQ's before they being destroyed. And once tasklets are killed, the hanlders are not expected to run. But because of core tasklet code issues, tasklet handler could still run even after tasklet_kill, RDS IB shutdown code already reaps the CQs before freeing cq/qp resources so as such the handlers have nothing left to do post shutdown. On other hand any handler running after teardown and trying to access already freed qp/cq resources causes issues Patch fixes this race by makes sure that handlers returns without any action post teardown. Reviewed-by: Wengang Signed-off-by: Santosh Shilimkar --- net/rds/ib.h | 1 + net/rds/ib_cm.c | 12 ++++++++++++ 2 files changed, 13 insertions(+) diff --git a/net/rds/ib.h b/net/rds/ib.h index 1fe9f79fead5..540458928f3c 100644 --- a/net/rds/ib.h +++ b/net/rds/ib.h @@ -185,6 +185,7 @@ struct rds_ib_connection { /* Endpoint role in connection */ bool i_active_side; + atomic_t i_cq_quiesce; /* Send/Recv vectors */ int i_scq_vector; diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c index 33c8584ada1f..ce3775abc6e7 100644 --- a/net/rds/ib_cm.c +++ b/net/rds/ib_cm.c @@ -128,6 +128,8 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even ic->i_flowctl ? ", flow control" : ""); } + atomic_set(&ic->i_cq_quiesce, 0); + /* Init rings and fill recv. this needs to wait until protocol * negotiation is complete, since ring layout is different * from 3.1 to 4.1. @@ -267,6 +269,10 @@ static void rds_ib_tasklet_fn_send(unsigned long data) rds_ib_stats_inc(s_ib_tasklet_call); + /* if cq has been already reaped, ignore incoming cq event */ + if (atomic_read(&ic->i_cq_quiesce)) + return; + poll_scq(ic, ic->i_send_cq, ic->i_send_wc); ib_req_notify_cq(ic->i_send_cq, IB_CQ_NEXT_COMP); poll_scq(ic, ic->i_send_cq, ic->i_send_wc); @@ -308,6 +314,10 @@ static void rds_ib_tasklet_fn_recv(unsigned long data) rds_ib_stats_inc(s_ib_tasklet_call); + /* if cq has been already reaped, ignore incoming cq event */ + if (atomic_read(&ic->i_cq_quiesce)) + return; + memset(&state, 0, sizeof(state)); poll_rcq(ic, ic->i_recv_cq, ic->i_recv_wc, &state); ib_req_notify_cq(ic->i_recv_cq, IB_CQ_SOLICITED); @@ -804,6 +814,8 @@ void rds_ib_conn_path_shutdown(struct rds_conn_path *cp) tasklet_kill(&ic->i_send_tasklet); tasklet_kill(&ic->i_recv_tasklet); + atomic_set(&ic->i_cq_quiesce, 1); + /* first destroy the ib state that generates callbacks */ if (ic->i_cm_id->qp) rdma_destroy_qp(ic->i_cm_id);