IB/srpt: Don't allow reordering of commands on wait list

If a receive I/O context is removed from the wait list and
srpt_handle_new_iu() fails to allocate a send I/O context then
re-adding the receive I/O context to the wait list can cause
reordering. Avoid this by only removing a receive I/O context
from the wait list after allocating a send I/O context succeeded.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index 372f1eb..5b2e74b 100644 (file)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -1533,39 +1533,39 @@ fail:
  * srpt_handle_new_iu - process a newly received information unit
  * @ch:    RDMA channel through which the information unit has been received.
  * @recv_ioctx: Receive I/O context associated with the information unit.
- * @send_ioctx: Send I/O context.
  */
-static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
-                              struct srpt_recv_ioctx *recv_ioctx,
-                              struct srpt_send_ioctx *send_ioctx)
+static bool
+srpt_handle_new_iu(struct srpt_rdma_ch *ch, struct srpt_recv_ioctx *recv_ioctx)
 {
+       struct srpt_send_ioctx *send_ioctx = NULL;
        struct srp_cmd *srp_cmd;
+       bool res = false;
+       u8 opcode;
 
        BUG_ON(!ch);
        BUG_ON(!recv_ioctx);
 
+       if (unlikely(ch->state == CH_CONNECTING))
+               goto push;
+
        ib_dma_sync_single_for_cpu(ch->sport->sdev->device,
                                   recv_ioctx->ioctx.dma, srp_max_req_size,
                                   DMA_FROM_DEVICE);
 
-       if (unlikely(ch->state == CH_CONNECTING))
-               goto out_wait;
-
-       if (unlikely(ch->state != CH_LIVE))
-               return;
-
        srp_cmd = recv_ioctx->ioctx.buf;
-       if (srp_cmd->opcode == SRP_CMD || srp_cmd->opcode == SRP_TSK_MGMT) {
-               if (!send_ioctx) {
-                       if (!list_empty(&ch->cmd_wait_list))
-                               goto out_wait;
-                       send_ioctx = srpt_get_send_ioctx(ch);
-               }
+       opcode = srp_cmd->opcode;
+       if (opcode == SRP_CMD || opcode == SRP_TSK_MGMT) {
+               send_ioctx = srpt_get_send_ioctx(ch);
                if (unlikely(!send_ioctx))
-                       goto out_wait;
+                       goto push;
        }
 
-       switch (srp_cmd->opcode) {
+       if (!list_empty(&recv_ioctx->wait_list)) {
+               WARN_ON_ONCE(!ch->processing_wait_list);
+               list_del_init(&recv_ioctx->wait_list);
+       }
+
+       switch (opcode) {
        case SRP_CMD:
                srpt_handle_cmd(ch, recv_ioctx, send_ioctx);
                break;
@@ -1585,16 +1585,22 @@ static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
                pr_err("Received SRP_RSP\n");
                break;
        default:
-               pr_err("received IU with unknown opcode 0x%x\n",
-                      srp_cmd->opcode);
+               pr_err("received IU with unknown opcode 0x%x\n", opcode);
                break;
        }
 
        srpt_post_recv(ch->sport->sdev, ch, recv_ioctx);
-       return;
+       res = true;
 
-out_wait:
-       list_add_tail(&recv_ioctx->wait_list, &ch->cmd_wait_list);
+out:
+       return res;
+
+push:
+       if (list_empty(&recv_ioctx->wait_list)) {
+               WARN_ON_ONCE(ch->processing_wait_list);
+               list_add_tail(&recv_ioctx->wait_list, &ch->cmd_wait_list);
+       }
+       goto out;
 }
 
 static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
@@ -1609,7 +1615,7 @@ static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
                req_lim = atomic_dec_return(&ch->req_lim);
                if (unlikely(req_lim < 0))
                        pr_err("req_lim = %d < 0\n", req_lim);
-               srpt_handle_new_iu(ch, ioctx, NULL);
+               srpt_handle_new_iu(ch, ioctx);
        } else {
                pr_info_ratelimited("receiving failed for ioctx %p with status %d\n",
                                    ioctx, wc->status);
@@ -1623,19 +1629,21 @@ static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
  */
 static void srpt_process_wait_list(struct srpt_rdma_ch *ch)
 {
-       struct srpt_send_ioctx *ioctx;
+       struct srpt_recv_ioctx *recv_ioctx, *tmp;
 
-       while (!list_empty(&ch->cmd_wait_list) &&
-              ch->state >= CH_LIVE &&
-              (ioctx = srpt_get_send_ioctx(ch)) != NULL) {
-               struct srpt_recv_ioctx *recv_ioctx;
+       WARN_ON_ONCE(ch->state == CH_CONNECTING);
 
-               recv_ioctx = list_first_entry(&ch->cmd_wait_list,
-                                             struct srpt_recv_ioctx,
-                                             wait_list);
-               list_del(&recv_ioctx->wait_list);
-               srpt_handle_new_iu(ch, recv_ioctx, ioctx);
+       if (list_empty(&ch->cmd_wait_list))
+               return;
+
+       WARN_ON_ONCE(ch->processing_wait_list);
+       ch->processing_wait_list = true;
+       list_for_each_entry_safe(recv_ioctx, tmp, &ch->cmd_wait_list,
+                                wait_list) {
+               if (!srpt_handle_new_iu(ch, recv_ioctx))
+                       break;
        }
+       ch->processing_wait_list = false;
 }
 
 /**
@@ -2150,6 +2158,8 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
                            cpu_to_be32(SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
                        goto free_ring;
                }
+               for (i = 0; i < ch->rq_size; i++)
+                       INIT_LIST_HEAD(&ch->ioctx_recv_ring[i]->wait_list);
        }
 
        ret = srpt_create_ch_ib(ch);
@@ -2773,8 +2783,10 @@ static int srpt_alloc_srq(struct srpt_device *sdev)
        sdev->use_srq = true;
        sdev->srq = srq;
 
-       for (i = 0; i < sdev->srq_size; ++i)
+       for (i = 0; i < sdev->srq_size; ++i) {
+               INIT_LIST_HEAD(&sdev->ioctx_ring[i]->wait_list);
                srpt_post_recv(sdev, NULL, sdev->ioctx_ring[i]);
+       }
 
        return 0;
 }

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.h b/drivers/infiniband/ulp/srpt/ib_srpt.h
index 59261d5..10f9b26 100644 (file)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.h
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.h
@@ -261,6 +261,7 @@ enum rdma_ch_state {
  * @spinlock:      Protects free_list and state.
  * @free_list:     Head of list with free send I/O contexts.
  * @state:         channel state. See also enum rdma_ch_state.
+ * @processing_wait_list: Whether or not cmd_wait_list is being processed.
  * @ioctx_ring:    Send ring.
  * @ioctx_recv_ring: Receive I/O context ring.
  * @list:          Node in srpt_nexus.ch_list.
@@ -295,6 +296,7 @@ struct srpt_rdma_ch {
        struct list_head        list;
        struct list_head        cmd_wait_list;
        uint16_t                pkey;
+       bool                    processing_wait_list;
        struct se_session       *sess;
        u8                      sess_name[24];
        struct work_struct      release_work;