scsi: lpfc: Fix kernel crash at lpfc_nvme_info_show during remote port bounce

When reading sysfs nvme_info file while a remote port leaves and comes
back, a NULL pointer is encountered. The issue is due to ndlp list
corruption as the the nvme_info_show does not use the same lock as the rest
of the code.

Correct by removing the rcu_xxx_lock calls and replace by the host_lock and
phba->hbaLock spinlocks that are used by the rest of the driver.  Given
we're called from sysfs, we are safe to use _irq rather than _irqsave.

Link: https://lore.kernel.org/r/20191105005708.7399-4-jsmart2021@gmail.com
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index 2d090ea..3f30bc0 100644 (file)
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -176,7 +176,6 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
        int i;
        int len = 0;
        char tmp[LPFC_MAX_NVME_INFO_TMP_LEN] = {0};
-       unsigned long iflags = 0;
 
        if (!(vport->cfg_enable_fc4_type & LPFC_ENABLE_NVME)) {
                len = scnprintf(buf, PAGE_SIZE, "NVME Disabled\n");
@@ -347,7 +346,6 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
        if (strlcat(buf, "\nNVME Initiator Enabled\n", PAGE_SIZE) >= PAGE_SIZE)
                goto buffer_done;
 
-       rcu_read_lock();
        scnprintf(tmp, sizeof(tmp),
                  "XRI Dist lpfc%d Total %d IO %d ELS %d\n",
                  phba->brd_no,
@@ -355,7 +353,7 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
                  phba->sli4_hba.io_xri_max,
                  lpfc_sli4_get_els_iocb_cnt(phba));
        if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-               goto rcu_unlock_buf_done;
+               goto buffer_done;
 
        /* Port state is only one of two values for now. */
        if (localport->port_id)
@@ -371,15 +369,17 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
                  wwn_to_u64(vport->fc_nodename.u.wwn),
                  localport->port_id, statep);
        if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-               goto rcu_unlock_buf_done;
+               goto buffer_done;
+
+       spin_lock_irq(shost->host_lock);
 
        list_for_each_entry(ndlp, &vport->fc_nodes, nlp_listp) {
                nrport = NULL;
-               spin_lock_irqsave(&vport->phba->hbalock, iflags);
+               spin_lock(&vport->phba->hbalock);
                rport = lpfc_ndlp_get_nrport(ndlp);
                if (rport)
                        nrport = rport->remoteport;
-               spin_unlock_irqrestore(&vport->phba->hbalock, iflags);
+               spin_unlock(&vport->phba->hbalock);
                if (!nrport)
                        continue;
 
@@ -398,39 +398,39 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
 
                /* Tab in to show lport ownership. */
                if (strlcat(buf, "NVME RPORT       ", PAGE_SIZE) >= PAGE_SIZE)
-                       goto rcu_unlock_buf_done;
+                       goto unlock_buf_done;
                if (phba->brd_no >= 10) {
                        if (strlcat(buf, " ", PAGE_SIZE) >= PAGE_SIZE)
-                               goto rcu_unlock_buf_done;
+                               goto unlock_buf_done;
                }
 
                scnprintf(tmp, sizeof(tmp), "WWPN x%llx ",
                          nrport->port_name);
                if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-                       goto rcu_unlock_buf_done;
+                       goto unlock_buf_done;
 
                scnprintf(tmp, sizeof(tmp), "WWNN x%llx ",
                          nrport->node_name);
                if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-                       goto rcu_unlock_buf_done;
+                       goto unlock_buf_done;
 
                scnprintf(tmp, sizeof(tmp), "DID x%06x ",
                          nrport->port_id);
                if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-                       goto rcu_unlock_buf_done;
+                       goto unlock_buf_done;
 
                /* An NVME rport can have multiple roles. */
                if (nrport->port_role & FC_PORT_ROLE_NVME_INITIATOR) {
                        if (strlcat(buf, "INITIATOR ", PAGE_SIZE) >= PAGE_SIZE)
-                               goto rcu_unlock_buf_done;
+                               goto unlock_buf_done;
                }
                if (nrport->port_role & FC_PORT_ROLE_NVME_TARGET) {
                        if (strlcat(buf, "TARGET ", PAGE_SIZE) >= PAGE_SIZE)
-                               goto rcu_unlock_buf_done;
+                               goto unlock_buf_done;
                }
                if (nrport->port_role & FC_PORT_ROLE_NVME_DISCOVERY) {
                        if (strlcat(buf, "DISCSRVC ", PAGE_SIZE) >= PAGE_SIZE)
-                               goto rcu_unlock_buf_done;
+                               goto unlock_buf_done;
                }
                if (nrport->port_role & ~(FC_PORT_ROLE_NVME_INITIATOR |
                                          FC_PORT_ROLE_NVME_TARGET |
@@ -438,14 +438,14 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
                        scnprintf(tmp, sizeof(tmp), "UNKNOWN ROLE x%x",
                                  nrport->port_role);
                        if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-                               goto rcu_unlock_buf_done;
+                               goto unlock_buf_done;
                }
 
                scnprintf(tmp, sizeof(tmp), "%s\n", statep);
                if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
-                       goto rcu_unlock_buf_done;
+                       goto unlock_buf_done;
        }
-       rcu_read_unlock();
+       spin_unlock_irq(shost->host_lock);
 
        if (!lport)
                goto buffer_done;
@@ -505,11 +505,11 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
                  atomic_read(&lport->cmpl_fcp_err));
        strlcat(buf, tmp, PAGE_SIZE);
 
-       /* RCU is already unlocked. */
+       /* host_lock is already unlocked. */
        goto buffer_done;
 
- rcu_unlock_buf_done:
-       rcu_read_unlock();
+ unlock_buf_done:
+       spin_unlock_irq(shost->host_lock);
 
  buffer_done:
        len = strnlen(buf, PAGE_SIZE);