iwpm: crash fix for large connections test

During large connection test, there is a crash at wake_up() in the callback as waitq is
not yet initialized. Callback can happen before iwpm_wait_complete_req() is called to
initialize waitq.
To resolve, using signaling semaphore instead of waitq.
Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Reviewed-by: Tatyana E Nikolova <tatyana.e.nikolova@intel.com>
Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/iwpm_msg.c

@@ -394,7 +394,7 @@ int iwpm_register_pid_cb(struct sk_buff *skb, struct netlink_callback *cb)
 	/* always for found nlmsg_request */
 	kref_put(&nlmsg_request->kref, iwpm_free_nlmsg_request);
 	barrier();
-	wake_up(&nlmsg_request->waitq);
+	up(&nlmsg_request->sem);
 	return 0;
 }
 EXPORT_SYMBOL(iwpm_register_pid_cb);
@@ -463,7 +463,7 @@ int iwpm_add_mapping_cb(struct sk_buff *skb, struct netlink_callback *cb)
 	/* always for found request */
 	kref_put(&nlmsg_request->kref, iwpm_free_nlmsg_request);
 	barrier();
-	wake_up(&nlmsg_request->waitq);
+	up(&nlmsg_request->sem);
 	return 0;
 }
 EXPORT_SYMBOL(iwpm_add_mapping_cb);
@@ -555,7 +555,7 @@ int iwpm_add_and_query_mapping_cb(struct sk_buff *skb,
 	/* always for found request */
 	kref_put(&nlmsg_request->kref, iwpm_free_nlmsg_request);
 	barrier();
-	wake_up(&nlmsg_request->waitq);
+	up(&nlmsg_request->sem);
 	return 0;
 }
 EXPORT_SYMBOL(iwpm_add_and_query_mapping_cb);
@@ -749,7 +749,7 @@ int iwpm_mapping_error_cb(struct sk_buff *skb, struct netlink_callback *cb)
 	/* always for found request */
 	kref_put(&nlmsg_request->kref, iwpm_free_nlmsg_request);
 	barrier();
-	wake_up(&nlmsg_request->waitq);
+	up(&nlmsg_request->sem);
 	return 0;
 }
 EXPORT_SYMBOL(iwpm_mapping_error_cb);

drivers/infiniband/core/iwpm_util.c

@@ -322,6 +322,8 @@ struct iwpm_nlmsg_request *iwpm_get_nlmsg_request(__u32 nlmsg_seq,
 	nlmsg_request->nl_client = nl_client;
 	nlmsg_request->request_done = 0;
 	nlmsg_request->err_code = 0;
+	sema_init(&nlmsg_request->sem, 1);
+	down(&nlmsg_request->sem);
 	return nlmsg_request;
 }
 
@@ -364,11 +366,9 @@ struct iwpm_nlmsg_request *iwpm_find_nlmsg_request(__u32 echo_seq)
 int iwpm_wait_complete_req(struct iwpm_nlmsg_request *nlmsg_request)
 {
 	int ret;
-	init_waitqueue_head(&nlmsg_request->waitq);
 
-	ret = wait_event_timeout(nlmsg_request->waitq,
-			(nlmsg_request->request_done != 0), IWPM_NL_TIMEOUT);
-	if (!ret) {
+	ret = down_timeout(&nlmsg_request->sem, IWPM_NL_TIMEOUT);
+	if (ret) {
 		ret = -EINVAL;
 		pr_info("%s: Timeout %d sec for netlink request (seq = %u)\n",
 			__func__, (IWPM_NL_TIMEOUT/HZ), nlmsg_request->nlmsg_seq);

drivers/infiniband/core/iwpm_util.h

@@ -69,7 +69,7 @@ struct iwpm_nlmsg_request {
 	u8	            nl_client;
 	u8                  request_done;
 	u16                 err_code;
-	wait_queue_head_t   waitq;
+	struct semaphore    sem;
 	struct kref         kref;
 };