diff options
author | Tyrel Datwyler <tyreld@linux.ibm.com> | 2020-10-25 03:13:55 +0300 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2020-10-27 00:14:40 +0300 |
commit | 665e0224a3d76f36da40bd9012270fa629aa42ed (patch) | |
tree | 2e2ad3b4d79b717de0df8d5985b8a917fdd4f608 | |
parent | 2f4843b172c2c0360ee7792ad98025fae7baefde (diff) | |
download | linux-665e0224a3d76f36da40bd9012270fa629aa42ed.tar.xz |
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>
-rw-r--r-- | drivers/scsi/ibmvscsi/ibmvscsi.c | 36 |
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)) { |