smb: client: remove separate empty_packet_queue

There's no need to maintain two lists, we can just
have a single list of receive buffers, which are free to use.

It just added unneeded complexity and resulted in
ib_dma_unmap_single() not being called from recv_done()
for empty keepalive packets.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Fixes: f198186 ("CIFS: SMBD: Establish SMB Direct connection")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: metze-samba

fs/smb/client/cifs_debug.c

@@ -481,10 +481,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 			server->smbd_conn->receive_credit_target);
 		seq_printf(m, "\nPending send_pending: %x ",
 			atomic_read(&server->smbd_conn->send_pending));
-		seq_printf(m, "\nReceive buffers count_receive_queue: %x "
-			"count_empty_packet_queue: %x",
-			server->smbd_conn->count_receive_queue,
-			server->smbd_conn->count_empty_packet_queue);
+		seq_printf(m, "\nReceive buffers count_receive_queue: %x ",
+			server->smbd_conn->count_receive_queue);
 		seq_printf(m, "\nMR responder_resources: %x "
 			"max_frmr_depth: %x mr_type: %x",
 			server->smbd_conn->responder_resources,

fs/smb/client/smbdirect.c

@@ -13,8 +13,6 @@
 #include "cifsproto.h"
 #include "smb2proto.h"
 
-static struct smbd_response *get_empty_queue_buffer(
-		struct smbd_connection *info);
 static struct smbd_response *get_receive_buffer(
 		struct smbd_connection *info);
 static void put_receive_buffer(
@@ -23,8 +21,6 @@ static void put_receive_buffer(
 static int allocate_receive_buffers(struct smbd_connection *info, int num_buf);
 static void destroy_receive_buffers(struct smbd_connection *info);
 
-static void put_empty_packet(
-		struct smbd_connection *info, struct smbd_response *response);
 static void enqueue_reassembly(
 		struct smbd_connection *info,
 		struct smbd_response *response, int data_length);
@@ -393,7 +389,6 @@ static bool process_negotiation_response(
 static void smbd_post_send_credits(struct work_struct *work)
 {
 	int ret = 0;
-	int use_receive_queue = 1;
 	int rc;
 	struct smbd_response *response;
 	struct smbd_connection *info =
@@ -409,18 +404,9 @@ static void smbd_post_send_credits(struct work_struct *work)
 	if (info->receive_credit_target >
 		atomic_read(&info->receive_credits)) {
 		while (true) {
-			if (use_receive_queue)
-				response = get_receive_buffer(info);
-			else
-				response = get_empty_queue_buffer(info);
-			if (!response) {
-				/* now switch to empty packet queue */
-				if (use_receive_queue) {
-					use_receive_queue = 0;
-					continue;
-				} else
-					break;
-			}
+			response = get_receive_buffer(info);
+			if (!response)
+				break;
 
 			response->type = SMBD_TRANSFER_DATA;
 			response->first_segment = false;
@@ -511,7 +497,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 				response,
 				data_length);
 		} else
-			put_empty_packet(info, response);
+			put_receive_buffer(info, response);
 
 		if (data_length)
 			wake_up_interruptible(&info->wait_reassembly_queue);
@@ -1115,17 +1101,6 @@ static int smbd_negotiate(struct smbd_connection *info)
 	return rc;
 }
 
-static void put_empty_packet(
-		struct smbd_connection *info, struct smbd_response *response)
-{
-	spin_lock(&info->empty_packet_queue_lock);
-	list_add_tail(&response->list, &info->empty_packet_queue);
-	info->count_empty_packet_queue++;
-	spin_unlock(&info->empty_packet_queue_lock);
-
-	queue_work(info->workqueue, &info->post_send_credits_work);
-}
-
 /*
  * Implement Connection.FragmentReassemblyBuffer defined in [MS-SMBD] 3.1.1.1
  * This is a queue for reassembling upper layer payload and present to upper
@@ -1174,25 +1149,6 @@ static struct smbd_response *_get_first_reassembly(struct smbd_connection *info)
 	return ret;
 }
 
-static struct smbd_response *get_empty_queue_buffer(
-		struct smbd_connection *info)
-{
-	struct smbd_response *ret = NULL;
-	unsigned long flags;
-
-	spin_lock_irqsave(&info->empty_packet_queue_lock, flags);
-	if (!list_empty(&info->empty_packet_queue)) {
-		ret = list_first_entry(
-			&info->empty_packet_queue,
-			struct smbd_response, list);
-		list_del(&ret->list);
-		info->count_empty_packet_queue--;
-	}
-	spin_unlock_irqrestore(&info->empty_packet_queue_lock, flags);
-
-	return ret;
-}
-
 /*
  * Get a receive buffer
  * For each remote send, we need to post a receive. The receive buffers are
@@ -1257,10 +1213,6 @@ static int allocate_receive_buffers(struct smbd_connection *info, int num_buf)
 	spin_lock_init(&info->receive_queue_lock);
 	info->count_receive_queue = 0;
 
-	INIT_LIST_HEAD(&info->empty_packet_queue);
-	spin_lock_init(&info->empty_packet_queue_lock);
-	info->count_empty_packet_queue = 0;
-
 	init_waitqueue_head(&info->wait_receive_queues);
 
 	for (i = 0; i < num_buf; i++) {
@@ -1294,9 +1246,6 @@ static void destroy_receive_buffers(struct smbd_connection *info)
 
 	while ((response = get_receive_buffer(info)))
 		mempool_free(response, info->response_mempool);
-
-	while ((response = get_empty_queue_buffer(info)))
-		mempool_free(response, info->response_mempool);
 }
 
 /* Implement idle connection timer [MS-SMBD] 3.1.6.2 */
@@ -1383,8 +1332,7 @@ void smbd_destroy(struct TCP_Server_Info *server)
 
 	log_rdma_event(INFO, "free receive buffers\n");
 	wait_event(info->wait_receive_queues,
-		info->count_receive_queue + info->count_empty_packet_queue
-			== sp->recv_credit_max);
+		info->count_receive_queue == sp->recv_credit_max);
 	destroy_receive_buffers(info);
 
 	/*

fs/smb/client/smbdirect.h

@@ -110,10 +110,6 @@ struct smbd_connection {
 	int count_receive_queue;
 	spinlock_t receive_queue_lock;
 
-	struct list_head empty_packet_queue;
-	int count_empty_packet_queue;
-	spinlock_t empty_packet_queue_lock;
-
 	wait_queue_head_t wait_receive_queues;
 
 	/* Reassembly queue */