IB/srp: Fix a race condition triggered by destroying a queue pair
At least LID reassignment can trigger a race condition in the SRP
initiator driver, namely the receive completion handler trying to
post a request on a QP during or after QP destruction and before
the CQ's have been destroyed. Avoid this race by modifying a QP
into the error state and by waiting until all receive completions
have been processed before destroying a QP.
Reported-by: Max Gurtuvoy <maxg@mellanox.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index aac844a..57b5ff1 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -453,6 +453,41 @@
dev->max_pages_per_mr);
}
+/**
+ * srp_destroy_qp() - destroy an RDMA queue pair
+ * @ch: SRP RDMA channel.
+ *
+ * Change a queue pair into the error state and wait until all receive
+ * completions have been processed before destroying it. This avoids that
+ * the receive completion handler can access the queue pair while it is
+ * being destroyed.
+ */
+static void srp_destroy_qp(struct srp_rdma_ch *ch)
+{
+ struct srp_target_port *target = ch->target;
+ static struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR };
+ static struct ib_recv_wr wr = { .wr_id = SRP_LAST_WR_ID };
+ struct ib_recv_wr *bad_wr;
+ int ret;
+
+ /* Destroying a QP and reusing ch->done is only safe if not connected */
+ WARN_ON_ONCE(target->connected);
+
+ ret = ib_modify_qp(ch->qp, &attr, IB_QP_STATE);
+ WARN_ONCE(ret, "ib_cm_init_qp_attr() returned %d\n", ret);
+ if (ret)
+ goto out;
+
+ init_completion(&ch->done);
+ ret = ib_post_recv(ch->qp, &wr, &bad_wr);
+ WARN_ONCE(ret, "ib_post_recv() returned %d\n", ret);
+ if (ret == 0)
+ wait_for_completion(&ch->done);
+
+out:
+ ib_destroy_qp(ch->qp);
+}
+
static int srp_create_ch_ib(struct srp_rdma_ch *ch)
{
struct srp_target_port *target = ch->target;
@@ -469,8 +504,9 @@
if (!init_attr)
return -ENOMEM;
+ /* + 1 for SRP_LAST_WR_ID */
recv_cq = ib_create_cq(dev->dev, srp_recv_completion, NULL, ch,
- target->queue_size, ch->comp_vector);
+ target->queue_size + 1, ch->comp_vector);
if (IS_ERR(recv_cq)) {
ret = PTR_ERR(recv_cq);
goto err;
@@ -487,7 +523,7 @@
init_attr->event_handler = srp_qp_event;
init_attr->cap.max_send_wr = m * target->queue_size;
- init_attr->cap.max_recv_wr = target->queue_size;
+ init_attr->cap.max_recv_wr = target->queue_size + 1;
init_attr->cap.max_recv_sge = 1;
init_attr->cap.max_send_sge = 1;
init_attr->sq_sig_type = IB_SIGNAL_REQ_WR;
@@ -530,7 +566,7 @@
}
if (ch->qp)
- ib_destroy_qp(ch->qp);
+ srp_destroy_qp(ch);
if (ch->recv_cq)
ib_destroy_cq(ch->recv_cq);
if (ch->send_cq)
@@ -586,7 +622,7 @@
if (ch->fmr_pool)
ib_destroy_fmr_pool(ch->fmr_pool);
}
- ib_destroy_qp(ch->qp);
+ srp_destroy_qp(ch);
ib_destroy_cq(ch->send_cq);
ib_destroy_cq(ch->recv_cq);
@@ -1883,8 +1919,15 @@
}
static void srp_handle_qp_err(u64 wr_id, enum ib_wc_status wc_status,
- bool send_err, struct srp_target_port *target)
+ bool send_err, struct srp_rdma_ch *ch)
{
+ struct srp_target_port *target = ch->target;
+
+ if (wr_id == SRP_LAST_WR_ID) {
+ complete(&ch->done);
+ return;
+ }
+
if (target->connected && !target->qp_in_error) {
if (wr_id & LOCAL_INV_WR_ID_MASK) {
shost_printk(KERN_ERR, target->scsi_host, PFX
@@ -1915,8 +1958,7 @@
if (likely(wc.status == IB_WC_SUCCESS)) {
srp_handle_recv(ch, &wc);
} else {
- srp_handle_qp_err(wc.wr_id, wc.status, false,
- ch->target);
+ srp_handle_qp_err(wc.wr_id, wc.status, false, ch);
}
}
}
@@ -1932,8 +1974,7 @@
iu = (struct srp_iu *) (uintptr_t) wc.wr_id;
list_add(&iu->list, &ch->free_tx);
} else {
- srp_handle_qp_err(wc.wr_id, wc.status, true,
- ch->target);
+ srp_handle_qp_err(wc.wr_id, wc.status, true, ch);
}
}
}