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RDMA/cma: Fix locking for the RDMA_CM_CONNECT state

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It is currently a bit confusing, but the design is if the handler_mutex
is held, and the state is in RDMA_CM_CONNECT, then the state cannot leave
RDMA_CM_CONNECT without also serializing with the handler_mutex.

Make this clearer by adding a direct assertion, fixing the usage in
rdma_connect and generally using READ_ONCE to read the state value.

Link: https://lore.kernel.org/r/20200902081122.745412-2-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe 2020-09-02 11:11:15 +03:00
parent 3cc30e8dfc
commit 2a7cec5381
1 changed files with 30 additions and 14 deletions
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44
drivers/infiniband/core/cma.c
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@ -421,6 +421,15 @@ static int cma_comp_exch(struct rdma_id_private *id_priv,
unsigned long flags;
int ret;
/*
* The FSM uses a funny double locking where state is protected by both
* the handler_mutex and the spinlock. State is not allowed to change
* away from a handler_mutex protected value without also holding
* handler_mutex.
*/
if (comp == RDMA_CM_CONNECT)
lockdep_assert_held(&id_priv->handler_mutex);
spin_lock_irqsave(&id_priv->lock, flags);
if ((ret = (id_priv->state == comp)))
id_priv->state = exch;
@ -1949,13 +1958,15 @@ static int cma_ib_handler(struct ib_cm_id *cm_id,
{
struct rdma_id_private *id_priv = cm_id->context;
struct rdma_cm_event event = {};
enum rdma_cm_state state;
int ret;
mutex_lock(&id_priv->handler_mutex);
state = READ_ONCE(id_priv->state);
if ((ib_event->event != IB_CM_TIMEWAIT_EXIT &&
id_priv->state != RDMA_CM_CONNECT) ||
state != RDMA_CM_CONNECT) ||
(ib_event->event == IB_CM_TIMEWAIT_EXIT &&
id_priv->state != RDMA_CM_DISCONNECT))
state != RDMA_CM_DISCONNECT))
goto out;
switch (ib_event->event) {
@ -1965,7 +1976,7 @@ static int cma_ib_handler(struct ib_cm_id *cm_id,
event.status = -ETIMEDOUT;
break;
case IB_CM_REP_RECEIVED:
if (cma_comp(id_priv, RDMA_CM_CONNECT) &&
if (state == RDMA_CM_CONNECT &&
(id_priv->id.qp_type != IB_QPT_UD)) {
trace_cm_send_mra(id_priv);
ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0);
@ -2226,8 +2237,8 @@ static int cma_ib_req_handler(struct ib_cm_id *cm_id,
goto net_dev_put;
}
if (cma_comp(conn_id, RDMA_CM_CONNECT) &&
(conn_id->id.qp_type != IB_QPT_UD)) {
if (READ_ONCE(conn_id->state) == RDMA_CM_CONNECT &&
conn_id->id.qp_type != IB_QPT_UD) {
trace_cm_send_mra(cm_id->context);
ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0);
}
@ -2288,7 +2299,7 @@ static int cma_iw_handler(struct iw_cm_id *iw_id, struct iw_cm_event *iw_event)
struct sockaddr *raddr = (struct sockaddr *)&iw_event->remote_addr;
mutex_lock(&id_priv->handler_mutex);
if (id_priv->state != RDMA_CM_CONNECT)
if (READ_ONCE(id_priv->state) != RDMA_CM_CONNECT)
goto out;
switch (iw_event->event) {
@ -3778,7 +3789,7 @@ static int cma_sidr_rep_handler(struct ib_cm_id *cm_id,
int ret;
mutex_lock(&id_priv->handler_mutex);
if (id_priv->state != RDMA_CM_CONNECT)
if (READ_ONCE(id_priv->state) != RDMA_CM_CONNECT)
goto out;
switch (ib_event->event) {
@ -4014,12 +4025,15 @@ out:
int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param)
{
struct rdma_id_private *id_priv;
struct rdma_id_private *id_priv =
container_of(id, struct rdma_id_private, id);
int ret;
id_priv = container_of(id, struct rdma_id_private, id);
if (!cma_comp_exch(id_priv, RDMA_CM_ROUTE_RESOLVED, RDMA_CM_CONNECT))
return -EINVAL;
mutex_lock(&id_priv->handler_mutex);
if (!cma_comp_exch(id_priv, RDMA_CM_ROUTE_RESOLVED, RDMA_CM_CONNECT)) {
ret = -EINVAL;
goto err_unlock;
}
if (!id->qp) {
id_priv->qp_num = conn_param->qp_num;
@ -4036,11 +4050,13 @@ int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param)
else
ret = -ENOSYS;
if (ret)
goto err;
goto err_state;
mutex_unlock(&id_priv->handler_mutex);
return 0;
err:
err_state:
cma_comp_exch(id_priv, RDMA_CM_CONNECT, RDMA_CM_ROUTE_RESOLVED);
err_unlock:
mutex_unlock(&id_priv->handler_mutex);
return ret;
}
EXPORT_SYMBOL(rdma_connect);