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Subject[PATCH 4.19 021/245] scsi: lpfc: Fix kernel crash at lpfc_nvme_info_show during remote port bounce
Date
From: James Smart <jsmart2021@gmail.com>

[ Upstream commit 6c1e803eac846f886cd35131e6516fc51a8414b9 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc_attr.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index fe084d47ed9e5..3447d19d4147a 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -332,7 +332,6 @@ 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 NVME %d SCSI %d ELS %d\n",
phba->brd_no,
@@ -341,7 +340,7 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
phba->sli4_hba.scsi_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)
@@ -357,7 +356,9 @@ 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;
@@ -384,39 +385,39 @@ 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 |
@@ -424,14 +425,14 @@ 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;
@@ -491,11 +492,11 @@ 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);
--
2.25.1


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