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>

1 files changed, 26 insertions, 28 deletions

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index f0c91ba3178a..c58ee771baaa 100644
--- 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;
 }