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scsi: ibmvfc: Fix invalid state machine BUG_ON()

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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: 73ee5d8672 ("[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>
This commit is contained in:
Brian King 2021-04-12 18:10:09 -06:00 committed by Martin K. Petersen
parent cf270817ca
commit 15cfef8623
1 changed files with 38 additions and 19 deletions
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43
drivers/scsi/ibmvscsi/ibmvfc.c
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@ -604,8 +604,17 @@ 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:
@ -615,15 +624,6 @@ 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;
}
}
@ -5380,31 +5380,50 @@ 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;
list_splice_init(&vhost->purge, &purge);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
ibmvfc_complete_purge(&purge);
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 (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;
list_splice_init(&vhost->purge, &purge);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
ibmvfc_complete_purge(&purge);
rc = ibmvfc_reenable_crq_queue(vhost);
spin_lock_irqsave(vhost->host->host_lock, flags);
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:
vhost->job_step(vhost);