IB/cma: Make the code easier to verify

Static source code analysis tools like smatch cannot handle functions
that lock or not lock a mutex depending on the value of the arguments.
Hence inline the function cma_disable_callback(). Additionally, this
patch realizes a small performance optimization by reducing the number of
mutex_lock() and mutex_unlock() calls in the modified functions. With
this patch applied smatch no longer complains about source file cma.c.
Without this patch smatch reports the following for this source file:

drivers/infiniband/core/cma.c:1959: cma_req_handler() warn: inconsistent returns 'mutex:&listen_id->handler_mutex'.
  Locked on:   line 1880
               line 1959
  Unlocked on: line 1941
drivers/infiniband/core/cma.c:2112: iw_conn_req_handler() warn: inconsistent returns 'mutex:&listen_id->handler_mutex'.
  Locked on:   line 2048
  Unlocked on: line 2112

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Steve Wise <swise@opengridcomputing.com>
Cc: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Sean Hefty <sean.hefty@intel.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index f0c91ba..c58ee77 100644 (file)
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -708,17 +708,6 @@ static void cma_deref_id(struct rdma_id_private *id_priv)
                complete(&id_priv->comp);
 }
 
-static int cma_disable_callback(struct rdma_id_private *id_priv,
-                               enum rdma_cm_state state)
-{
-       mutex_lock(&id_priv->handler_mutex);
-       if (id_priv->state != state) {
-               mutex_unlock(&id_priv->handler_mutex);
-               return -EINVAL;
-       }
-       return 0;
-}
-
 struct rdma_cm_id *rdma_create_id(struct net *net,
                                  rdma_cm_event_handler event_handler,
                                  void *context, enum rdma_port_space ps,
@@ -1671,11 +1660,12 @@ static int cma_ib_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event)
        struct rdma_cm_event event;
        int ret = 0;
 
+       mutex_lock(&id_priv->handler_mutex);
        if ((ib_event->event != IB_CM_TIMEWAIT_EXIT &&
-               cma_disable_callback(id_priv, RDMA_CM_CONNECT)) ||
+            id_priv->state != RDMA_CM_CONNECT) ||
            (ib_event->event == IB_CM_TIMEWAIT_EXIT &&
-               cma_disable_callback(id_priv, RDMA_CM_DISCONNECT)))
-               return 0;
+            id_priv->state != RDMA_CM_DISCONNECT))
+               goto out;
 
        memset(&event, 0, sizeof event);
        switch (ib_event->event) {
@@ -1870,7 +1860,7 @@ static int cma_check_req_qp_type(struct rdma_cm_id *id, struct ib_cm_event *ib_e
 
 static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event)
 {
-       struct rdma_id_private *listen_id, *conn_id;
+       struct rdma_id_private *listen_id, *conn_id = NULL;
        struct rdma_cm_event event;
        struct net_device *net_dev;
        int offset, ret;
@@ -1884,9 +1874,10 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event)
                goto net_dev_put;
        }
 
-       if (cma_disable_callback(listen_id, RDMA_CM_LISTEN)) {
+       mutex_lock(&listen_id->handler_mutex);
+       if (listen_id->state != RDMA_CM_LISTEN) {
                ret = -ECONNABORTED;
-               goto net_dev_put;
+               goto err1;
        }
 
        memset(&event, 0, sizeof event);
@@ -1976,8 +1967,9 @@ static int cma_iw_handler(struct iw_cm_id *iw_id, struct iw_cm_event *iw_event)
        struct sockaddr *laddr = (struct sockaddr *)&iw_event->local_addr;
        struct sockaddr *raddr = (struct sockaddr *)&iw_event->remote_addr;
 
-       if (cma_disable_callback(id_priv, RDMA_CM_CONNECT))
-               return 0;
+       mutex_lock(&id_priv->handler_mutex);
+       if (id_priv->state != RDMA_CM_CONNECT)
+               goto out;
 
        memset(&event, 0, sizeof event);
        switch (iw_event->event) {
@@ -2029,6 +2021,7 @@ static int cma_iw_handler(struct iw_cm_id *iw_id, struct iw_cm_event *iw_event)
                return ret;
        }
 
+out:
        mutex_unlock(&id_priv->handler_mutex);
        return ret;
 }
@@ -2039,13 +2032,15 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id,
        struct rdma_cm_id *new_cm_id;
        struct rdma_id_private *listen_id, *conn_id;
        struct rdma_cm_event event;
-       int ret;
+       int ret = -ECONNABORTED;
        struct sockaddr *laddr = (struct sockaddr *)&iw_event->local_addr;
        struct sockaddr *raddr = (struct sockaddr *)&iw_event->remote_addr;
 
        listen_id = cm_id->context;
-       if (cma_disable_callback(listen_id, RDMA_CM_LISTEN))
-               return -ECONNABORTED;
+
+       mutex_lock(&listen_id->handler_mutex);
+       if (listen_id->state != RDMA_CM_LISTEN)
+               goto out;
 
        /* Create a new RDMA id for the new IW CM ID */
        new_cm_id = rdma_create_id(listen_id->id.route.addr.dev_addr.net,
@@ -3216,8 +3211,9 @@ static int cma_sidr_rep_handler(struct ib_cm_id *cm_id,
        struct ib_cm_sidr_rep_event_param *rep = &ib_event->param.sidr_rep_rcvd;
        int ret = 0;
 
-       if (cma_disable_callback(id_priv, RDMA_CM_CONNECT))
-               return 0;
+       mutex_lock(&id_priv->handler_mutex);
+       if (id_priv->state != RDMA_CM_CONNECT)
+               goto out;
 
        memset(&event, 0, sizeof event);
        switch (ib_event->event) {
@@ -3673,12 +3669,13 @@ static int cma_ib_mc_handler(int status, struct ib_sa_multicast *multicast)
        struct rdma_id_private *id_priv;
        struct cma_multicast *mc = multicast->context;
        struct rdma_cm_event event;
-       int ret;
+       int ret = 0;
 
        id_priv = mc->id_priv;
-       if (cma_disable_callback(id_priv, RDMA_CM_ADDR_BOUND) &&
-           cma_disable_callback(id_priv, RDMA_CM_ADDR_RESOLVED))
-               return 0;
+       mutex_lock(&id_priv->handler_mutex);
+       if (id_priv->state != RDMA_CM_ADDR_BOUND &&
+           id_priv->state != RDMA_CM_ADDR_RESOLVED)
+               goto out;
 
        if (!status)
                status = cma_set_qkey(id_priv, be32_to_cpu(multicast->rec.qkey));
@@ -3720,6 +3717,7 @@ static int cma_ib_mc_handler(int status, struct ib_sa_multicast *multicast)
                return 0;
        }
 
+out:
        mutex_unlock(&id_priv->handler_mutex);
        return 0;
 }