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IB/iser: Simplify connection management

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iSER relies on refcounting to manage iser connections establishment
and teardown.

Following commit 39ff05dbbb ("IB/iser: Enhance disconnection logic
for multi-pathing"), iser connection maintain 3 references:

 - iscsi_endpoint (at creation stage)
 - cma_id (at connection request stage)
 - iscsi_conn (at bind stage)

We can avoid taking explicit refcounts by correctly serializing iser
teardown flows (graceful and non-graceful).

Our approach is to trigger a scheduled work to handle ordered teardown
by gracefully waiting for 2 cleanup stages to complete:

 1. Cleanup of live pending tasks indicated by iscsi_conn_stop completion
 2. Flush errors processing

Each completed stage will notify a waiting worker thread when it is
done to allow teardwon continuation.

Since iSCSI connection establishment may trigger endpoint disconnect
without a successful endpoint connect, we rely on the iscsi <-> iser
binding (.conn_bind) to learn about the teardown policy we should take
wrt cleanup stages.

Since all cleanup worker threads are scheduled (release_wq) in
.ep_disconnect it is safe to assume that when module_exit is called,
all cleanup workers are already scheduled. Thus proper module unload
shall flush all scheduled works before allowing safe exit, to
guarantee no resources got left behind.

Signed-off-by: Ariel Nahum <arieln@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
This commit is contained in:
Ariel Nahum 2014-05-22 11:00:18 +03:00 committed by Roland Dreier
parent d6d211db37
commit b73c3adabd
3 changed files with 99 additions and 91 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

97
drivers/infiniband/ulp/iser/iscsi_iser.c
View file

@ -99,6 +99,7 @@ MODULE_PARM_DESC(pi_enable, "Enable T10-PI offload support (default:disabled)");
module_param_named(pi_guard, iser_pi_guard, int, 0644);
MODULE_PARM_DESC(pi_guard, "T10-PI guard_type, 0:CRC|1:IP_CSUM (default:CRC)");
static struct workqueue_struct *release_wq;
struct iser_global ig;
void
@ -337,24 +338,6 @@ iscsi_iser_conn_create(struct iscsi_cls_session *cls_session, uint32_t conn_idx)
return cls_conn;
}
static void
iscsi_iser_conn_destroy(struct iscsi_cls_conn *cls_conn)
{
struct iscsi_conn *conn = cls_conn->dd_data;
struct iser_conn *ib_conn = conn->dd_data;
iscsi_conn_teardown(cls_conn);
/*
* Userspace will normally call the stop callback and
* already have freed the ib_conn, but if it goofed up then
* we free it here.
*/
if (ib_conn) {
ib_conn->iscsi_conn = NULL;
iser_conn_put(ib_conn, 1); /* deref iscsi/ib conn unbinding */
}
}
static int
iscsi_iser_conn_bind(struct iscsi_cls_session *cls_session,
struct iscsi_cls_conn *cls_conn, uint64_t transport_eph,
@ -392,29 +375,39 @@ iscsi_iser_conn_bind(struct iscsi_cls_session *cls_session,
conn->dd_data = ib_conn;
ib_conn->iscsi_conn = conn;
iser_conn_get(ib_conn); /* ref iscsi/ib conn binding */
return 0;
}
static int
iscsi_iser_conn_start(struct iscsi_cls_conn *cls_conn)
{
struct iscsi_conn *iscsi_conn;
struct iser_conn *ib_conn;
iscsi_conn = cls_conn->dd_data;
ib_conn = iscsi_conn->dd_data;
reinit_completion(&ib_conn->stop_completion);
return iscsi_conn_start(cls_conn);
}
static void
iscsi_iser_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
{
struct iscsi_conn *conn = cls_conn->dd_data;
struct iser_conn *ib_conn = conn->dd_data;
iser_dbg("stopping iscsi_conn: %p, ib_conn: %p\n", conn, ib_conn);
iscsi_conn_stop(cls_conn, flag);
/*
* Userspace may have goofed up and not bound the connection or
* might have only partially setup the connection.
*/
if (ib_conn) {
iscsi_conn_stop(cls_conn, flag);
/*
* There is no unbind event so the stop callback
* must release the ref from the bind.
*/
iser_conn_put(ib_conn, 1); /* deref iscsi/ib conn unbinding */
conn->dd_data = NULL;
complete(&ib_conn->stop_completion);
}
conn->dd_data = NULL;
}
static void iscsi_iser_session_destroy(struct iscsi_cls_session *cls_session)
@ -652,19 +645,20 @@ iscsi_iser_ep_disconnect(struct iscsi_endpoint *ep)
struct iser_conn *ib_conn;
ib_conn = ep->dd_data;
if (ib_conn->iscsi_conn)
/*
* Must suspend xmit path if the ep is bound to the
* iscsi_conn, so we know we are not accessing the ib_conn
* when we free it.
*
* This may not be bound if the ep poll failed.
*/
iscsi_suspend_tx(ib_conn->iscsi_conn);
iser_info("ib conn %p state %d\n", ib_conn, ib_conn->state);
iser_info("ep %p ib conn %p state %d\n", ep, ib_conn, ib_conn->state);
iser_conn_terminate(ib_conn);
/*
* if iser_conn and iscsi_conn are bound, we must wait iscsi_conn_stop
* call and ISER_CONN_DOWN state before freeing the iser resources.
* otherwise we are safe to free resources immediately.
*/
if (ib_conn->iscsi_conn) {
INIT_WORK(&ib_conn->release_work, iser_release_work);
queue_work(release_wq, &ib_conn->release_work);
} else {
iser_conn_release(ib_conn);
}
}
static umode_t iser_attr_is_visible(int param_type, int param)
@ -748,13 +742,13 @@ static struct iscsi_transport iscsi_iser_transport = {
/* connection management */
.create_conn = iscsi_iser_conn_create,
.bind_conn = iscsi_iser_conn_bind,
.destroy_conn = iscsi_iser_conn_destroy,
.destroy_conn = iscsi_conn_teardown,
.attr_is_visible = iser_attr_is_visible,
.set_param = iscsi_iser_set_param,
.get_conn_param = iscsi_conn_get_param,
.get_ep_param = iscsi_iser_get_ep_param,
.get_session_param = iscsi_session_get_param,
.start_conn = iscsi_conn_start,
.start_conn = iscsi_iser_conn_start,
.stop_conn = iscsi_iser_conn_stop,
/* iscsi host params */
.get_host_param = iscsi_host_get_param,
@ -801,6 +795,12 @@ static int __init iser_init(void)
mutex_init(&ig.connlist_mutex);
INIT_LIST_HEAD(&ig.connlist);
release_wq = alloc_workqueue("release workqueue", 0, 0);
if (!release_wq) {
iser_err("failed to allocate release workqueue\n");
return -ENOMEM;
}
iscsi_iser_scsi_transport = iscsi_register_transport(
&iscsi_iser_transport);
if (!iscsi_iser_scsi_transport) {
@ -819,7 +819,24 @@ static int __init iser_init(void)
static void __exit iser_exit(void)
{
struct iser_conn *ib_conn, *n;
int connlist_empty;
iser_dbg("Removing iSER datamover...\n");
destroy_workqueue(release_wq);
mutex_lock(&ig.connlist_mutex);
connlist_empty = list_empty(&ig.connlist);
mutex_unlock(&ig.connlist_mutex);
if (!connlist_empty) {
iser_err("Error cleanup stage completed but we still have iser "
"connections, destroying them anyway.\n");
list_for_each_entry_safe(ib_conn, n, &ig.connlist, conn_list) {
iser_conn_release(ib_conn);
}
}
iscsi_unregister_transport(&iscsi_iser_transport);
kmem_cache_destroy(ig.desc_cache);
}

8
drivers/infiniband/ulp/iser/iscsi_iser.h
View file

@ -333,6 +333,8 @@ struct iser_conn {
int post_recv_buf_count; /* posted rx count */
atomic_t post_send_buf_count; /* posted tx count */
char name[ISER_OBJECT_NAME_SIZE];
struct work_struct release_work;
struct completion stop_completion;
struct list_head conn_list; /* entry in ig conn list */
char *login_buf;
@ -417,12 +419,12 @@ void iscsi_iser_recv(struct iscsi_conn *conn,
void iser_conn_init(struct iser_conn *ib_conn);
void iser_conn_get(struct iser_conn *ib_conn);
int iser_conn_put(struct iser_conn *ib_conn, int destroy_cma_id_allowed);
void iser_conn_release(struct iser_conn *ib_conn);
void iser_conn_terminate(struct iser_conn *ib_conn);
void iser_release_work(struct work_struct *work);
void iser_rcv_completion(struct iser_rx_desc *desc,
unsigned long dto_xfer_len,
struct iser_conn *ib_conn);

85
drivers/infiniband/ulp/iser/iser_verbs.c
View file

@ -581,14 +581,30 @@ static int iser_conn_state_comp_exch(struct iser_conn *ib_conn,
return ret;
}
void iser_release_work(struct work_struct *work)
{
struct iser_conn *ib_conn;
ib_conn = container_of(work, struct iser_conn, release_work);
/* wait for .conn_stop callback */
wait_for_completion(&ib_conn->stop_completion);
/* wait for the qp`s post send and post receive buffers to empty */
wait_event_interruptible(ib_conn->wait,
ib_conn->state == ISER_CONN_DOWN);
iser_conn_release(ib_conn);
}
/**
* Frees all conn objects and deallocs conn descriptor
*/
static void iser_conn_release(struct iser_conn *ib_conn, int can_destroy_id)
void iser_conn_release(struct iser_conn *ib_conn)
{
struct iser_device *device = ib_conn->device;
BUG_ON(ib_conn->state != ISER_CONN_DOWN);
BUG_ON(ib_conn->state == ISER_CONN_UP);
mutex_lock(&ig.connlist_mutex);
list_del(&ib_conn->conn_list);
@ -600,27 +616,13 @@ static void iser_conn_release(struct iser_conn *ib_conn, int can_destroy_id)
if (device != NULL)
iser_device_try_release(device);
/* if cma handler context, the caller actually destroy the id */
if (ib_conn->cma_id != NULL && can_destroy_id) {
if (ib_conn->cma_id != NULL) {
rdma_destroy_id(ib_conn->cma_id);
ib_conn->cma_id = NULL;
}
iscsi_destroy_endpoint(ib_conn->ep);
}
void iser_conn_get(struct iser_conn *ib_conn)
{
atomic_inc(&ib_conn->refcount);
}
int iser_conn_put(struct iser_conn *ib_conn, int can_destroy_id)
{
if (atomic_dec_and_test(&ib_conn->refcount)) {
iser_conn_release(ib_conn, can_destroy_id);
return 1;
}
return 0;
}
/**
* triggers start of the disconnect procedures and wait for them to be done
*/
@ -638,24 +640,19 @@ void iser_conn_terminate(struct iser_conn *ib_conn)
if (err)
iser_err("Failed to disconnect, conn: 0x%p err %d\n",
ib_conn,err);
wait_event_interruptible(ib_conn->wait,
ib_conn->state == ISER_CONN_DOWN);
iser_conn_put(ib_conn, 1); /* deref ib conn deallocate */
}
static int iser_connect_error(struct rdma_cm_id *cma_id)
static void iser_connect_error(struct rdma_cm_id *cma_id)
{
struct iser_conn *ib_conn;
ib_conn = (struct iser_conn *)cma_id->context;
ib_conn->state = ISER_CONN_DOWN;
wake_up_interruptible(&ib_conn->wait);
return iser_conn_put(ib_conn, 0); /* deref ib conn's cma id */
}
static int iser_addr_handler(struct rdma_cm_id *cma_id)
static void iser_addr_handler(struct rdma_cm_id *cma_id)
{
struct iser_device *device;
struct iser_conn *ib_conn;
@ -664,7 +661,8 @@ static int iser_addr_handler(struct rdma_cm_id *cma_id)
device = iser_device_find_by_ib_device(cma_id);
if (!device) {
iser_err("device lookup/creation failed\n");
return iser_connect_error(cma_id);
iser_connect_error(cma_id);
return;
}
ib_conn = (struct iser_conn *)cma_id->context;
@ -686,13 +684,12 @@ static int iser_addr_handler(struct rdma_cm_id *cma_id)
ret = rdma_resolve_route(cma_id, 1000);
if (ret) {
iser_err("resolve route failed: %d\n", ret);
return iser_connect_error(cma_id);
iser_connect_error(cma_id);
return;
}
return 0;
}
static int iser_route_handler(struct rdma_cm_id *cma_id)
static void iser_route_handler(struct rdma_cm_id *cma_id)
{
struct rdma_conn_param conn_param;
int ret;
@ -720,9 +717,9 @@ static int iser_route_handler(struct rdma_cm_id *cma_id)
goto failure;
}
return 0;
return;
failure:
return iser_connect_error(cma_id);
iser_connect_error(cma_id);
}
static void iser_connected_handler(struct rdma_cm_id *cma_id)
@ -739,10 +736,9 @@ static void iser_connected_handler(struct rdma_cm_id *cma_id)
wake_up_interruptible(&ib_conn->wait);
}
static int iser_disconnected_handler(struct rdma_cm_id *cma_id)
static void iser_disconnected_handler(struct rdma_cm_id *cma_id)
{
struct iser_conn *ib_conn;
int ret;
ib_conn = (struct iser_conn *)cma_id->context;
@ -762,24 +758,19 @@ static int iser_disconnected_handler(struct rdma_cm_id *cma_id)
ib_conn->state = ISER_CONN_DOWN;
wake_up_interruptible(&ib_conn->wait);
}
ret = iser_conn_put(ib_conn, 0); /* deref ib conn's cma id */
return ret;
}
static int iser_cma_handler(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
{
int ret = 0;
iser_info("event %d status %d conn %p id %p\n",
event->event, event->status, cma_id->context, cma_id);
switch (event->event) {
case RDMA_CM_EVENT_ADDR_RESOLVED:
ret = iser_addr_handler(cma_id);
iser_addr_handler(cma_id);
break;
case RDMA_CM_EVENT_ROUTE_RESOLVED:
ret = iser_route_handler(cma_id);
iser_route_handler(cma_id);
break;
case RDMA_CM_EVENT_ESTABLISHED:
iser_connected_handler(cma_id);
@ -789,18 +780,18 @@ static int iser_cma_handler(struct rdma_cm_id *cma_id, struct rdma_cm_event *eve
case RDMA_CM_EVENT_CONNECT_ERROR:
case RDMA_CM_EVENT_UNREACHABLE:
case RDMA_CM_EVENT_REJECTED:
ret = iser_connect_error(cma_id);
iser_connect_error(cma_id);
break;
case RDMA_CM_EVENT_DISCONNECTED:
case RDMA_CM_EVENT_DEVICE_REMOVAL:
case RDMA_CM_EVENT_ADDR_CHANGE:
ret = iser_disconnected_handler(cma_id);
iser_disconnected_handler(cma_id);
break;
default:
iser_err("Unexpected RDMA CM event (%d)\n", event->event);
break;
}
return ret;
return 0;
}
void iser_conn_init(struct iser_conn *ib_conn)
@ -809,7 +800,7 @@ void iser_conn_init(struct iser_conn *ib_conn)
init_waitqueue_head(&ib_conn->wait);
ib_conn->post_recv_buf_count = 0;
atomic_set(&ib_conn->post_send_buf_count, 0);
atomic_set(&ib_conn->refcount, 1); /* ref ib conn allocation */
init_completion(&ib_conn->stop_completion);
INIT_LIST_HEAD(&ib_conn->conn_list);
spin_lock_init(&ib_conn->lock);
}
@ -837,7 +828,6 @@ int iser_connect(struct iser_conn *ib_conn,
ib_conn->state = ISER_CONN_PENDING;
iser_conn_get(ib_conn); /* ref ib conn's cma id */
ib_conn->cma_id = rdma_create_id(iser_cma_handler,
(void *)ib_conn,
RDMA_PS_TCP, IB_QPT_RC);
@ -874,9 +864,8 @@ int iser_connect(struct iser_conn *ib_conn,
ib_conn->cma_id = NULL;
addr_failure:
ib_conn->state = ISER_CONN_DOWN;
iser_conn_put(ib_conn, 1); /* deref ib conn's cma id */
connect_failure:
iser_conn_put(ib_conn, 1); /* deref ib conn deallocate */
iser_conn_release(ib_conn);
return err;
}