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authorTyrel Datwyler <tyreld@linux.ibm.com>2020-10-24 19:13:55 -0500
committerMartin K. Petersen <martin.petersen@oracle.com>2020-10-26 17:14:40 -0400
commit665e0224a3d76f36da40bd9012270fa629aa42ed (patch)
tree2e2ad3b4d79b717de0df8d5985b8a917fdd4f608 /drivers/scsi
parent2f4843b172c2c0360ee7792ad98025fae7baefde (diff)
downloadlinux-665e0224a3d76f36da40bd9012270fa629aa42ed.tar.bz2
scsi: ibmvscsi: Fix potential race after loss of transport
After a loss of transport due to an adapter migration or crash/disconnect from the host partner there is a tiny window where we can race adjusting the request_limit of the adapter. The request limit is atomically increased/decreased to track the number of inflight requests against the allowed limit of our VIOS partner. After a transport loss we set the request_limit to zero to reflect this state. However, there is a window where the adapter may attempt to queue a command because the transport loss event hasn't been fully processed yet and request_limit is still greater than zero. The hypercall to send the event will fail and the error path will increment the request_limit as a result. If the adapter processes the transport event prior to this increment the request_limit becomes out of sync with the adapter state and can result in SCSI commands being submitted on the now reset connection prior to an SRP Login resulting in a protocol violation. Fix this race by protecting request_limit with the host lock when changing the value via atomic_set() to indicate no transport. Link: https://lore.kernel.org/r/20201025001355.4527-1-tyreld@linux.ibm.com Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/ibmvscsi/ibmvscsi.c36
1 files changed, 26 insertions, 10 deletions
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index b1f3017b6547..29fcc44be2d5 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -807,13 +807,29 @@ static void purge_requests(struct ibmvscsi_host_data *hostdata, int error_code)
}
/**
+ * ibmvscsi_set_request_limit - Set the adapter request_limit in response to
+ * an adapter failure, reset, or SRP Login. Done under host lock to prevent
+ * race with SCSI command submission.
+ * @hostdata: adapter to adjust
+ * @limit: new request limit
+ */
+static void ibmvscsi_set_request_limit(struct ibmvscsi_host_data *hostdata, int limit)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(hostdata->host->host_lock, flags);
+ atomic_set(&hostdata->request_limit, limit);
+ spin_unlock_irqrestore(hostdata->host->host_lock, flags);
+}
+
+/**
* ibmvscsi_reset_host - Reset the connection to the server
* @hostdata: struct ibmvscsi_host_data to reset
*/
static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata)
{
scsi_block_requests(hostdata->host);
- atomic_set(&hostdata->request_limit, 0);
+ ibmvscsi_set_request_limit(hostdata, 0);
purge_requests(hostdata, DID_ERROR);
hostdata->action = IBMVSCSI_HOST_ACTION_RESET;
@@ -1146,13 +1162,13 @@ static void login_rsp(struct srp_event_struct *evt_struct)
dev_info(hostdata->dev, "SRP_LOGIN_REJ reason %u\n",
evt_struct->xfer_iu->srp.login_rej.reason);
/* Login failed. */
- atomic_set(&hostdata->request_limit, -1);
+ ibmvscsi_set_request_limit(hostdata, -1);
return;
default:
dev_err(hostdata->dev, "Invalid login response typecode 0x%02x!\n",
evt_struct->xfer_iu->srp.login_rsp.opcode);
/* Login failed. */
- atomic_set(&hostdata->request_limit, -1);
+ ibmvscsi_set_request_limit(hostdata, -1);
return;
}
@@ -1163,7 +1179,7 @@ static void login_rsp(struct srp_event_struct *evt_struct)
* This value is set rather than added to request_limit because
* request_limit could have been set to -1 by this client.
*/
- atomic_set(&hostdata->request_limit,
+ ibmvscsi_set_request_limit(hostdata,
be32_to_cpu(evt_struct->xfer_iu->srp.login_rsp.req_lim_delta));
/* If we had any pending I/Os, kick them */
@@ -1195,13 +1211,13 @@ static int send_srp_login(struct ibmvscsi_host_data *hostdata)
login->req_buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
SRP_BUF_FORMAT_INDIRECT);
- spin_lock_irqsave(hostdata->host->host_lock, flags);
/* Start out with a request limit of 0, since this is negotiated in
* the login request we are just sending and login requests always
* get sent by the driver regardless of request_limit.
*/
- atomic_set(&hostdata->request_limit, 0);
+ ibmvscsi_set_request_limit(hostdata, 0);
+ spin_lock_irqsave(hostdata->host->host_lock, flags);
rc = ibmvscsi_send_srp_event(evt_struct, hostdata, login_timeout * 2);
spin_unlock_irqrestore(hostdata->host->host_lock, flags);
dev_info(hostdata->dev, "sent SRP login\n");
@@ -1781,7 +1797,7 @@ static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
return;
case VIOSRP_CRQ_XPORT_EVENT: /* Hypervisor telling us the connection is closed */
scsi_block_requests(hostdata->host);
- atomic_set(&hostdata->request_limit, 0);
+ ibmvscsi_set_request_limit(hostdata, 0);
if (crq->format == 0x06) {
/* We need to re-setup the interpartition connection */
dev_info(hostdata->dev, "Re-enabling adapter!\n");
@@ -2137,12 +2153,12 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
}
hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
+ spin_unlock_irqrestore(hostdata->host->host_lock, flags);
if (rc) {
- atomic_set(&hostdata->request_limit, -1);
+ ibmvscsi_set_request_limit(hostdata, -1);
dev_err(hostdata->dev, "error after %s\n", action);
}
- spin_unlock_irqrestore(hostdata->host->host_lock, flags);
scsi_unblock_requests(hostdata->host);
}
@@ -2226,7 +2242,7 @@ static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id)
init_waitqueue_head(&hostdata->work_wait_q);
hostdata->host = host;
hostdata->dev = dev;
- atomic_set(&hostdata->request_limit, -1);
+ ibmvscsi_set_request_limit(hostdata, -1);
hostdata->host->max_sectors = IBMVSCSI_MAX_SECTORS_DEFAULT;
if (map_persist_bufs(hostdata)) {