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Subject[PATCH 5.10 335/530] scsi: ibmvfc: Fix invalid state machine BUG_ON()
Date
From: Brian King <brking@linux.vnet.ibm.com>

[ Upstream commit 15cfef8623a449d40d16541687afd58e78033be3 ]

This fixes an issue hitting the BUG_ON() in ibmvfc_do_work(). When going
through a host action of IBMVFC_HOST_ACTION_RESET, we change the action to
IBMVFC_HOST_ACTION_TGT_DEL, then drop the host lock, and reset the CRQ,
which changes the host state to IBMVFC_NO_CRQ. If, prior to setting the
host state to IBMVFC_NO_CRQ, ibmvfc_init_host() is called, it can then end
up changing the host action to IBMVFC_HOST_ACTION_INIT. If we then change
the host state to IBMVFC_NO_CRQ, we will then hit the BUG_ON().

Make a couple of changes to avoid this. Leave the host action to be
IBMVFC_HOST_ACTION_RESET or IBMVFC_HOST_ACTION_REENABLE until after we drop
the host lock and reset or reenable the CRQ. Also harden the host state
machine to ensure we cannot leave the reset / reenable state until we've
finished processing the reset or reenable.

Link: https://lore.kernel.org/r/20210413001009.902400-1-tyreld@linux.ibm.com
Fixes: 73ee5d867287 ("[SCSI] ibmvfc: Fix soft lockup on resume")
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
[tyreld: added fixes tag]
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
[mkp: fix comment checkpatch warnings]
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 57 ++++++++++++++++++++++------------
1 file changed, 38 insertions(+), 19 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 57c9a71fa33a..f6d6539c657f 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -532,8 +532,17 @@ static void ibmvfc_set_host_action(struct ibmvfc_host *vhost,
if (vhost->action == IBMVFC_HOST_ACTION_ALLOC_TGTS)
vhost->action = action;
break;
+ case IBMVFC_HOST_ACTION_REENABLE:
+ case IBMVFC_HOST_ACTION_RESET:
+ vhost->action = action;
+ break;
case IBMVFC_HOST_ACTION_INIT:
case IBMVFC_HOST_ACTION_TGT_DEL:
+ case IBMVFC_HOST_ACTION_LOGO:
+ case IBMVFC_HOST_ACTION_QUERY_TGTS:
+ case IBMVFC_HOST_ACTION_TGT_DEL_FAILED:
+ case IBMVFC_HOST_ACTION_NONE:
+ default:
switch (vhost->action) {
case IBMVFC_HOST_ACTION_RESET:
case IBMVFC_HOST_ACTION_REENABLE:
@@ -543,15 +552,6 @@ static void ibmvfc_set_host_action(struct ibmvfc_host *vhost,
break;
}
break;
- case IBMVFC_HOST_ACTION_LOGO:
- case IBMVFC_HOST_ACTION_QUERY_TGTS:
- case IBMVFC_HOST_ACTION_TGT_DEL_FAILED:
- case IBMVFC_HOST_ACTION_NONE:
- case IBMVFC_HOST_ACTION_RESET:
- case IBMVFC_HOST_ACTION_REENABLE:
- default:
- vhost->action = action;
- break;
}
}

@@ -4658,26 +4658,45 @@ static void ibmvfc_do_work(struct ibmvfc_host *vhost)
case IBMVFC_HOST_ACTION_INIT_WAIT:
break;
case IBMVFC_HOST_ACTION_RESET:
- vhost->action = IBMVFC_HOST_ACTION_TGT_DEL;
spin_unlock_irqrestore(vhost->host->host_lock, flags);
rc = ibmvfc_reset_crq(vhost);
+
spin_lock_irqsave(vhost->host->host_lock, flags);
- if (rc == H_CLOSED)
+ if (!rc || rc == H_CLOSED)
vio_enable_interrupts(to_vio_dev(vhost->dev));
- if (rc || (rc = ibmvfc_send_crq_init(vhost)) ||
- (rc = vio_enable_interrupts(to_vio_dev(vhost->dev)))) {
- ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
- dev_err(vhost->dev, "Error after reset (rc=%d)\n", rc);
+ if (vhost->action == IBMVFC_HOST_ACTION_RESET) {
+ /*
+ * The only action we could have changed to would have
+ * been reenable, in which case, we skip the rest of
+ * this path and wait until we've done the re-enable
+ * before sending the crq init.
+ */
+ vhost->action = IBMVFC_HOST_ACTION_TGT_DEL;
+
+ if (rc || (rc = ibmvfc_send_crq_init(vhost)) ||
+ (rc = vio_enable_interrupts(to_vio_dev(vhost->dev)))) {
+ ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+ dev_err(vhost->dev, "Error after reset (rc=%d)\n", rc);
+ }
}
break;
case IBMVFC_HOST_ACTION_REENABLE:
- vhost->action = IBMVFC_HOST_ACTION_TGT_DEL;
spin_unlock_irqrestore(vhost->host->host_lock, flags);
rc = ibmvfc_reenable_crq_queue(vhost);
+
spin_lock_irqsave(vhost->host->host_lock, flags);
- if (rc || (rc = ibmvfc_send_crq_init(vhost))) {
- ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
- dev_err(vhost->dev, "Error after enable (rc=%d)\n", rc);
+ if (vhost->action == IBMVFC_HOST_ACTION_REENABLE) {
+ /*
+ * The only action we could have changed to would have
+ * been reset, in which case, we skip the rest of this
+ * path and wait until we've done the reset before
+ * sending the crq init.
+ */
+ vhost->action = IBMVFC_HOST_ACTION_TGT_DEL;
+ if (rc || (rc = ibmvfc_send_crq_init(vhost))) {
+ ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+ dev_err(vhost->dev, "Error after enable (rc=%d)\n", rc);
+ }
}
break;
case IBMVFC_HOST_ACTION_LOGO:
--
2.30.2


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