Commit 5e9dd03726ad ("scsi: ibmvfc: send NVMe target discovery MAD")
introduced concurrent SCSI and NVMe discover-target MADs.
ibmvfc_discover_targets_done() unconditionally set
IBMVFC_HOST_ACTION_ALLOC_TGTS on the first completion to arrive.
ibmvfc_alloc_targets() ran immediately and read both channels'
disc_buf and num_targets fields while the slower protocol's MAD was
still in flight. The slower protocol's num_targets remained zero from
the previous cycle, silently dropping all targets for that protocol.
The second completion attempted to transition to ALLOC_TGTS again but
the state machine had already advanced, so the transition was a no-op
and ibmvfc_alloc_targets() was never re-run.

Fix this by serializing discovery: send the SCSI discover-targets MAD
first and wait for its completion before sending the NVMe MAD.
ibmvfc_discover_scsi_targets_done() advances the job_step to
ibmvfc_discover_nvme_targets() when NVMe is active, or transitions
directly to IBMVFC_HOST_ACTION_ALLOC_TGTS when it is not.
ibmvfc_discover_nvme_targets_done() then transitions to ALLOC_TGTS
after the NVMe buffer is fully written. This guarantees that
ibmvfc_alloc_targets() is only called after both discovery buffers
are complete with no shared counter and no concurrent MADs in flight.

Fixes: 5e9dd03726ad ("scsi: ibmvfc: send NVMe target discovery MAD")
Signed-off-by: Tyrel Datwyler <[email protected]>
---
 drivers/scsi/ibmvscsi/ibmvfc-core.c | 115 +++++++++++++++++++---------
 1 file changed, 79 insertions(+), 36 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc-core.c 
b/drivers/scsi/ibmvscsi/ibmvfc-core.c
index ca9a0437fc0c..46d6b94cb96d 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc-core.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc-core.c
@@ -184,6 +184,7 @@ static void ibmvfc_tgt_send_prli(struct ibmvfc_target *);
 static void ibmvfc_tgt_send_plogi(struct ibmvfc_target *);
 static void ibmvfc_tgt_query_target(struct ibmvfc_target *);
 static void ibmvfc_npiv_logout(struct ibmvfc_host *);
+static void ibmvfc_discover_nvme_targets(struct ibmvfc_host *);
 static void ibmvfc_tgt_implicit_logout_and_del(struct ibmvfc_target *);
 static void ibmvfc_tgt_move_login(struct ibmvfc_target *);
 
@@ -5137,45 +5138,80 @@ static int ibmvfc_alloc_targets(struct ibmvfc_host 
*vhost)
 }
 
 /**
- * ibmvfc_discover_targets_done - Completion handler for discover targets MAD
+ * ibmvfc_discover_scsi_targets_done - Completion handler for SCSI discover 
targets MAD
  * @evt:       ibmvfc event struct
  *
  **/
-static void ibmvfc_discover_targets_done(struct ibmvfc_event *evt)
+static void ibmvfc_discover_scsi_targets_done(struct ibmvfc_event *evt)
 {
        struct ibmvfc_host *vhost = evt->vhost;
        struct ibmvfc_discover_targets *rsp = &evt->xfer_iu->discover_targets;
-       struct ibmvfc_channels *channels;
        u32 mad_status = be16_to_cpu(rsp->common.status);
-       u32 opcode = be32_to_cpu(rsp->common.opcode);
        int level = IBMVFC_DEFAULT_LOG_LEVEL;
 
-       if (opcode == IBMVFC_DISC_TARGETS)
-               channels = &vhost->scsi_scrqs;
-       else
-               channels = &vhost->nvme_scrqs;
+       switch (mad_status) {
+       case IBMVFC_MAD_SUCCESS:
+               ibmvfc_dbg(vhost, "Discover SCSI Targets succeeded\n");
+               vhost->scsi_scrqs.num_targets = min_t(u32, 
be32_to_cpu(rsp->num_written),
+                                                     max_targets);
+               ibmvfc_dbg(vhost, "%d SCSI targets found\n",
+                          vhost->scsi_scrqs.num_targets);
+               if (ibmvfc_nvme_active(vhost)) {
+                       ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT);
+                       vhost->job_step = ibmvfc_discover_nvme_targets;
+               } else {
+                       ibmvfc_set_host_action(vhost, 
IBMVFC_HOST_ACTION_ALLOC_TGTS);
+               }
+               break;
+       case IBMVFC_MAD_FAILED:
+               level += ibmvfc_retry_host_init(vhost);
+               ibmvfc_log(vhost, level, "Discover SCSI Targets failed: %s 
(%x:%x)\n",
+                          ibmvfc_get_cmd_error(be16_to_cpu(rsp->status), 
be16_to_cpu(rsp->error)),
+                          be16_to_cpu(rsp->status), be16_to_cpu(rsp->error));
+               break;
+       case IBMVFC_MAD_DRIVER_FAILED:
+               break;
+       default:
+               dev_err(vhost->dev, "Invalid Discover SCSI Targets response: 
0x%x\n", mad_status);
+               ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+               break;
+       }
+
+       ibmvfc_free_event(evt);
+       wake_up(&vhost->work_wait_q);
+}
+
+/**
+ * ibmvfc_discover_nvme_targets_done - Completion handler for NVMe discover 
targets MAD
+ * @evt:       ibmvfc event struct
+ *
+ **/
+static void ibmvfc_discover_nvme_targets_done(struct ibmvfc_event *evt)
+{
+       struct ibmvfc_host *vhost = evt->vhost;
+       struct ibmvfc_discover_targets *rsp = &evt->xfer_iu->discover_targets;
+       u32 mad_status = be16_to_cpu(rsp->common.status);
+       int level = IBMVFC_DEFAULT_LOG_LEVEL;
 
        switch (mad_status) {
        case IBMVFC_MAD_SUCCESS:
-               ibmvfc_dbg(vhost, "Discover %s Targets succeeded\n",
-                          proto_type[channels->protocol]);
-               channels->num_targets = min_t(u32, 
be32_to_cpu(rsp->num_written),
-                                             max_targets);
-               ibmvfc_dbg(vhost, "%d %s targets found\n", 
channels->num_targets,
-                          proto_type[channels->protocol]);
+               ibmvfc_dbg(vhost, "Discover NVMe Targets succeeded\n");
+               vhost->nvme_scrqs.num_targets = min_t(u32, 
be32_to_cpu(rsp->num_written),
+                                                     max_targets);
+               ibmvfc_dbg(vhost, "%d NVMe targets found\n",
+                          vhost->nvme_scrqs.num_targets);
                ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_ALLOC_TGTS);
                break;
        case IBMVFC_MAD_FAILED:
                level += ibmvfc_retry_host_init(vhost);
-               ibmvfc_log(vhost, level, "Discover %s Targets failed: %s 
(%x:%x)\n",
-                          proto_type[channels->protocol],
+               ibmvfc_log(vhost, level, "Discover NVMe Targets failed: %s 
(%x:%x)\n",
                           ibmvfc_get_cmd_error(be16_to_cpu(rsp->status), 
be16_to_cpu(rsp->error)),
                           be16_to_cpu(rsp->status), be16_to_cpu(rsp->error));
                break;
        case IBMVFC_MAD_DRIVER_FAILED:
                break;
        default:
-               dev_err(vhost->dev, "Invalid Discover Targets response: 
0x%x\n", mad_status);
+               dev_err(vhost->dev, "Invalid Discover NVMe Targets response: 
0x%x\n", mad_status);
                ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
                break;
        }
@@ -5184,7 +5220,8 @@ static void ibmvfc_discover_targets_done(struct 
ibmvfc_event *evt)
        wake_up(&vhost->work_wait_q);
 }
 
-static struct ibmvfc_event *ibmvfc_get_disc_event(struct ibmvfc_channels 
*channels)
+static struct ibmvfc_event *ibmvfc_get_disc_event(struct ibmvfc_channels 
*channels,
+                                                 void (*done)(struct 
ibmvfc_event *))
 {
        struct ibmvfc_discover_targets *mad;
        struct ibmvfc_host *vhost = ibmvfc_channels_to_vhost(channels);
@@ -5193,7 +5230,7 @@ static struct ibmvfc_event *ibmvfc_get_disc_event(struct 
ibmvfc_channels *channe
        if (!evt)
                return NULL;
 
-       ibmvfc_init_event(evt, ibmvfc_discover_targets_done, IBMVFC_MAD_FORMAT);
+       ibmvfc_init_event(evt, done, IBMVFC_MAD_FORMAT);
        mad = &evt->iu.discover_targets;
        memset(mad, 0, sizeof(*mad));
        mad->common.version = cpu_to_be32(1);
@@ -5211,17 +5248,18 @@ static struct ibmvfc_event 
*ibmvfc_get_disc_event(struct ibmvfc_channels *channe
 }
 
 /**
- * ibmvfc_discover_targets - Send Discover Targets MAD
+ * ibmvfc_discover_nvme_targets - Send Discover NVMe Targets MAD
  * @vhost:     ibmvfc host struct
  *
  **/
-static void ibmvfc_discover_targets(struct ibmvfc_host *vhost)
+static void ibmvfc_discover_nvme_targets(struct ibmvfc_host *vhost)
 {
-       struct ibmvfc_event *evt = ibmvfc_get_disc_event(&vhost->scsi_scrqs);
+       struct ibmvfc_event *evt = ibmvfc_get_disc_event(&vhost->nvme_scrqs,
+                                                        
ibmvfc_discover_nvme_targets_done);
        int level = IBMVFC_DEFAULT_LOG_LEVEL;
 
        if (!evt) {
-               ibmvfc_log(vhost, level, "Discover SCSI Targets failed: no 
available events\n");
+               ibmvfc_log(vhost, level, "Discover NVMe Targets failed: no 
available events\n");
                ibmvfc_hard_reset_host(vhost);
                return;
        }
@@ -5229,29 +5267,34 @@ static void ibmvfc_discover_targets(struct ibmvfc_host 
*vhost)
        ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT_WAIT);
 
        if (!ibmvfc_send_event(evt, vhost, default_timeout))
-               ibmvfc_dbg(vhost, "Sent discover SCSI targets\n");
+               ibmvfc_dbg(vhost, "Sent discover NVMe targets\n");
        else
-               goto link_down;
+               ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+}
 
-       if (!ibmvfc_nvme_active(vhost))
-               return;
+/**
+ * ibmvfc_discover_targets - Send Discover SCSI Targets MAD
+ * @vhost:     ibmvfc host struct
+ *
+ **/
+static void ibmvfc_discover_targets(struct ibmvfc_host *vhost)
+{
+       struct ibmvfc_event *evt = ibmvfc_get_disc_event(&vhost->scsi_scrqs,
+                                                        
ibmvfc_discover_scsi_targets_done);
+       int level = IBMVFC_DEFAULT_LOG_LEVEL;
 
-       evt = ibmvfc_get_disc_event(&vhost->nvme_scrqs);
        if (!evt) {
-               ibmvfc_log(vhost, level, "Discover NVMe Targets failed: no 
available events\n");
+               ibmvfc_log(vhost, level, "Discover SCSI Targets failed: no 
available events\n");
                ibmvfc_hard_reset_host(vhost);
                return;
        }
 
+       ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT_WAIT);
+
        if (!ibmvfc_send_event(evt, vhost, default_timeout))
-               ibmvfc_dbg(vhost, "Sent discover NVMe targets\n");
+               ibmvfc_dbg(vhost, "Sent discover SCSI targets\n");
        else
-               goto link_down;
-
-       return;
-
-link_down:
-       ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+               ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
 }
 
 static void ibmvfc_fabric_login_nvme_done(struct ibmvfc_event *evt)
-- 
2.55.0


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