smb: client: rename server mid_lock to mid_queue_lock

This is step 1/4 of a patch series to fix mid_q_entry memory leaks
caused by race conditions in callback execution.

The current mid_lock name is somewhat ambiguous about what it protects.
To prepare for splitting this lock into separate, more granular locks,
this patch renames mid_lock to mid_queue_lock to clearly indicate its
specific responsibility for protecting the pending_mid_q list and
related queue operations.

No functional changes are made in this patch - it only prepares the
codebase for the lock splitting that follows.

- mid_queue_lock for queue operations
- mid_counter_lock for mid counter operations
- per-mid locks for individual mid state management

Signed-off-by: Wang Zhaolong <[email protected]>
Acked-by: Enzo Matsumiya <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: Wang Zhaolong

fs/smb/client/cifs_debug.c

@@ -60,7 +60,7 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
 		return;
 
 	cifs_dbg(VFS, "Dump pending requests:\n");
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
 		cifs_dbg(VFS, "State: %d Cmd: %d Pid: %d Cbdata: %p Mid %llu\n",
 			 mid_entry->mid_state,
@@ -83,7 +83,7 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
 				mid_entry->resp_buf, 62);
 		}
 	}
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 #endif /* CONFIG_CIFS_DEBUG2 */
 }
 
@@ -672,7 +672,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 
 				seq_printf(m, "\n\tServer ConnectionId: 0x%llx",
 					   chan_server->conn_id);
-				spin_lock(&chan_server->mid_lock);
+				spin_lock(&chan_server->mid_queue_lock);
 				list_for_each_entry(mid_entry, &chan_server->pending_mid_q, qhead) {
 					seq_printf(m, "\n\t\tState: %d com: %d pid: %d cbdata: %p mid %llu",
 						   mid_entry->mid_state,
@@ -681,7 +681,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 						   mid_entry->callback_data,
 						   mid_entry->mid);
 				}
-				spin_unlock(&chan_server->mid_lock);
+				spin_unlock(&chan_server->mid_queue_lock);
 			}
 			spin_unlock(&ses->chan_lock);
 			seq_puts(m, "\n--\n");

fs/smb/client/cifsglob.h

@@ -732,7 +732,7 @@ struct TCP_Server_Info {
 #endif
 	wait_queue_head_t response_q;
 	wait_queue_head_t request_q; /* if more than maxmpx to srvr must block*/
-	spinlock_t mid_lock;  /* protect mid queue and it's entries */
+	spinlock_t mid_queue_lock;  /* protect mid queue */
 	struct list_head pending_mid_q;
 	bool noblocksnd;		/* use blocking sendmsg */
 	bool noautotune;		/* do not autotune send buf sizes */
@@ -2007,7 +2007,7 @@ require use of the stronger protocol */
  *				GlobalCurrentXid
  *				GlobalTotalActiveXid
  * TCP_Server_Info->srv_lock	(anything in struct not protected by another lock and can change)
- * TCP_Server_Info->mid_lock	TCP_Server_Info->pending_mid_q	cifs_get_tcp_session
+ * TCP_Server_Info->mid_queue_lock	TCP_Server_Info->pending_mid_q	cifs_get_tcp_session
  *				->CurrentMid
  *				(any changes in mid_q_entry fields)
  * TCP_Server_Info->req_lock	TCP_Server_Info->in_flight	cifs_get_tcp_session

fs/smb/client/connect.c

@@ -321,15 +321,15 @@ cifs_abort_connection(struct TCP_Server_Info *server)
 	/* mark submitted MIDs for retry and issue callback */
 	INIT_LIST_HEAD(&retry_list);
 	cifs_dbg(FYI, "%s: moving mids to private list\n", __func__);
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	list_for_each_entry_safe(mid, nmid, &server->pending_mid_q, qhead) {
 		kref_get(&mid->refcount);
 		if (mid->mid_state == MID_REQUEST_SUBMITTED)
 			mid->mid_state = MID_RETRY_NEEDED;
 		list_move(&mid->qhead, &retry_list);
 		mid->mid_flags |= MID_DELETED;
 	}
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 	cifs_server_unlock(server);
 
 	cifs_dbg(FYI, "%s: issuing mid callbacks\n", __func__);
@@ -884,13 +884,13 @@ is_smb_response(struct TCP_Server_Info *server, unsigned char type)
 			 * server there should be exactly one pending mid
 			 * corresponding to SMB1/SMB2 Negotiate packet.
 			 */
-			spin_lock(&server->mid_lock);
+			spin_lock(&server->mid_queue_lock);
 			list_for_each_entry_safe(mid, nmid, &server->pending_mid_q, qhead) {
 				kref_get(&mid->refcount);
 				list_move(&mid->qhead, &dispose_list);
 				mid->mid_flags |= MID_DELETED;
 			}
-			spin_unlock(&server->mid_lock);
+			spin_unlock(&server->mid_queue_lock);
 
 			/* Now try to reconnect once with NetBIOS session. */
 			server->with_rfc1001 = true;
@@ -957,7 +957,7 @@ dequeue_mid(struct mid_q_entry *mid, bool malformed)
 #ifdef CONFIG_CIFS_STATS2
 	mid->when_received = jiffies;
 #endif
-	spin_lock(&mid->server->mid_lock);
+	spin_lock(&mid->server->mid_queue_lock);
 	if (!malformed)
 		mid->mid_state = MID_RESPONSE_RECEIVED;
 	else
@@ -967,12 +967,12 @@ dequeue_mid(struct mid_q_entry *mid, bool malformed)
 	 * function has finished processing it is a bug.
 	 */
 	if (mid->mid_flags & MID_DELETED) {
-		spin_unlock(&mid->server->mid_lock);
+		spin_unlock(&mid->server->mid_queue_lock);
 		pr_warn_once("trying to dequeue a deleted mid\n");
 	} else {
 		list_del_init(&mid->qhead);
 		mid->mid_flags |= MID_DELETED;
-		spin_unlock(&mid->server->mid_lock);
+		spin_unlock(&mid->server->mid_queue_lock);
 	}
 }
 
@@ -1101,7 +1101,7 @@ clean_demultiplex_info(struct TCP_Server_Info *server)
 		struct list_head *tmp, *tmp2;
 		LIST_HEAD(dispose_list);
 
-		spin_lock(&server->mid_lock);
+		spin_lock(&server->mid_queue_lock);
 		list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
 			mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
 			cifs_dbg(FYI, "Clearing mid %llu\n", mid_entry->mid);
@@ -1110,7 +1110,7 @@ clean_demultiplex_info(struct TCP_Server_Info *server)
 			list_move(&mid_entry->qhead, &dispose_list);
 			mid_entry->mid_flags |= MID_DELETED;
 		}
-		spin_unlock(&server->mid_lock);
+		spin_unlock(&server->mid_queue_lock);
 
 		/* now walk dispose list and issue callbacks */
 		list_for_each_safe(tmp, tmp2, &dispose_list) {
@@ -1822,7 +1822,7 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
 	tcp_ses->compression.requested = ctx->compress;
 	spin_lock_init(&tcp_ses->req_lock);
 	spin_lock_init(&tcp_ses->srv_lock);
-	spin_lock_init(&tcp_ses->mid_lock);
+	spin_lock_init(&tcp_ses->mid_queue_lock);
 	INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);
 	INIT_LIST_HEAD(&tcp_ses->smb_ses_list);
 	INIT_DELAYED_WORK(&tcp_ses->echo, cifs_echo_request);

fs/smb/client/smb1ops.c

@@ -95,17 +95,17 @@ cifs_find_mid(struct TCP_Server_Info *server, char *buffer)
 	struct smb_hdr *buf = (struct smb_hdr *)buffer;
 	struct mid_q_entry *mid;
 
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	list_for_each_entry(mid, &server->pending_mid_q, qhead) {
 		if (compare_mid(mid->mid, buf) &&
 		    mid->mid_state == MID_REQUEST_SUBMITTED &&
 		    le16_to_cpu(mid->command) == buf->Command) {
 			kref_get(&mid->refcount);
-			spin_unlock(&server->mid_lock);
+			spin_unlock(&server->mid_queue_lock);
 			return mid;
 		}
 	}
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 	return NULL;
 }
 
@@ -169,7 +169,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 	__u16 last_mid, cur_mid;
 	bool collision, reconnect = false;
 
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 
 	/* mid is 16 bit only for CIFS/SMB */
 	cur_mid = (__u16)((server->CurrentMid) & 0xffff);
@@ -228,7 +228,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		}
 		cur_mid++;
 	}
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 
 	if (reconnect) {
 		cifs_signal_cifsd_for_reconnect(server, false);

fs/smb/client/smb2ops.c

@@ -374,19 +374,19 @@ smb2_get_next_mid(struct TCP_Server_Info *server)
 {
 	__u64 mid;
 	/* for SMB2 we need the current value */
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	mid = server->CurrentMid++;
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 	return mid;
 }
 
 static void
 smb2_revert_current_mid(struct TCP_Server_Info *server, const unsigned int val)
 {
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	if (server->CurrentMid >= val)
 		server->CurrentMid -= val;
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 }
 
 static struct mid_q_entry *
@@ -401,7 +401,7 @@ __smb2_find_mid(struct TCP_Server_Info *server, char *buf, bool dequeue)
 		return NULL;
 	}
 
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	list_for_each_entry(mid, &server->pending_mid_q, qhead) {
 		if ((mid->mid == wire_mid) &&
 		    (mid->mid_state == MID_REQUEST_SUBMITTED) &&
@@ -411,11 +411,11 @@ __smb2_find_mid(struct TCP_Server_Info *server, char *buf, bool dequeue)
 				list_del_init(&mid->qhead);
 				mid->mid_flags |= MID_DELETED;
 			}
-			spin_unlock(&server->mid_lock);
+			spin_unlock(&server->mid_queue_lock);
 			return mid;
 		}
 	}
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 	return NULL;
 }
 
@@ -460,9 +460,9 @@ smb2_negotiate(const unsigned int xid,
 {
 	int rc;
 
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	server->CurrentMid = 0;
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 	rc = SMB2_negotiate(xid, ses, server);
 	return rc;
 }
@@ -4809,18 +4809,18 @@ static void smb2_decrypt_offload(struct work_struct *work)
 		} else {
 			spin_lock(&dw->server->srv_lock);
 			if (dw->server->tcpStatus == CifsNeedReconnect) {
-				spin_lock(&dw->server->mid_lock);
+				spin_lock(&dw->server->mid_queue_lock);
 				mid->mid_state = MID_RETRY_NEEDED;
-				spin_unlock(&dw->server->mid_lock);
+				spin_unlock(&dw->server->mid_queue_lock);
 				spin_unlock(&dw->server->srv_lock);
 				mid->callback(mid);
 			} else {
-				spin_lock(&dw->server->mid_lock);
+				spin_lock(&dw->server->mid_queue_lock);
 				mid->mid_state = MID_REQUEST_SUBMITTED;
 				mid->mid_flags &= ~(MID_DELETED);
 				list_add_tail(&mid->qhead,
 					&dw->server->pending_mid_q);
-				spin_unlock(&dw->server->mid_lock);
+				spin_unlock(&dw->server->mid_queue_lock);
 				spin_unlock(&dw->server->srv_lock);
 			}
 		}

fs/smb/client/smb2transport.c

@@ -840,9 +840,9 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server,
 	*mid = smb2_mid_entry_alloc(shdr, server);
 	if (*mid == NULL)
 		return -ENOMEM;
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	list_add_tail(&(*mid)->qhead, &server->pending_mid_q);
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 
 	return 0;
 }

fs/smb/client/transport.c

@@ -160,12 +160,12 @@ void __release_mid(struct kref *refcount)
 void
 delete_mid(struct mid_q_entry *mid)
 {
-	spin_lock(&mid->server->mid_lock);
+	spin_lock(&mid->server->mid_queue_lock);
 	if (!(mid->mid_flags & MID_DELETED)) {
 		list_del_init(&mid->qhead);
 		mid->mid_flags |= MID_DELETED;
 	}
-	spin_unlock(&mid->server->mid_lock);
+	spin_unlock(&mid->server->mid_queue_lock);
 
 	release_mid(mid);
 }
@@ -716,9 +716,9 @@ static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
 	*ppmidQ = alloc_mid(in_buf, ses->server);
 	if (*ppmidQ == NULL)
 		return -ENOMEM;
-	spin_lock(&ses->server->mid_lock);
+	spin_lock(&ses->server->mid_queue_lock);
 	list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
-	spin_unlock(&ses->server->mid_lock);
+	spin_unlock(&ses->server->mid_queue_lock);
 	return 0;
 }
 
@@ -819,9 +819,9 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
 	mid->mid_state = MID_REQUEST_SUBMITTED;
 
 	/* put it on the pending_mid_q */
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	list_add_tail(&mid->qhead, &server->pending_mid_q);
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 
 	/*
 	 * Need to store the time in mid before calling I/O. For call_async,
@@ -880,10 +880,10 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
 	cifs_dbg(FYI, "%s: cmd=%d mid=%llu state=%d\n",
 		 __func__, le16_to_cpu(mid->command), mid->mid, mid->mid_state);
 
-	spin_lock(&server->mid_lock);
+	spin_lock(&server->mid_queue_lock);
 	switch (mid->mid_state) {
 	case MID_RESPONSE_READY:
-		spin_unlock(&server->mid_lock);
+		spin_unlock(&server->mid_queue_lock);
 		return rc;
 	case MID_RETRY_NEEDED:
 		rc = -EAGAIN;
@@ -902,13 +902,13 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
 			list_del_init(&mid->qhead);
 			mid->mid_flags |= MID_DELETED;
 		}
-		spin_unlock(&server->mid_lock);
+		spin_unlock(&server->mid_queue_lock);
 		cifs_server_dbg(VFS, "%s: invalid mid state mid=%llu state=%d\n",
 			 __func__, mid->mid, mid->mid_state);
 		rc = -EIO;
 		goto sync_mid_done;
 	}
-	spin_unlock(&server->mid_lock);
+	spin_unlock(&server->mid_queue_lock);
 
 sync_mid_done:
 	release_mid(mid);
@@ -1213,15 +1213,15 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 			cifs_server_dbg(FYI, "Cancelling wait for mid %llu cmd: %d\n",
 				 midQ[i]->mid, le16_to_cpu(midQ[i]->command));
 			send_cancel(server, &rqst[i], midQ[i]);
-			spin_lock(&server->mid_lock);
+			spin_lock(&server->mid_queue_lock);
 			midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
 			if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED ||
 			    midQ[i]->mid_state == MID_RESPONSE_RECEIVED) {
 				midQ[i]->callback = cifs_cancelled_callback;
 				cancelled_mid[i] = true;
 				credits[i].value = 0;
 			}
-			spin_unlock(&server->mid_lock);
+			spin_unlock(&server->mid_queue_lock);
 		}
 	}
 
@@ -1423,16 +1423,16 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
 	rc = wait_for_response(server, midQ);
 	if (rc != 0) {
 		send_cancel(server, &rqst, midQ);
-		spin_lock(&server->mid_lock);
+		spin_lock(&server->mid_queue_lock);
 		if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
 		    midQ->mid_state == MID_RESPONSE_RECEIVED) {
 			/* no longer considered to be "in-flight" */
 			midQ->callback = release_mid;
-			spin_unlock(&server->mid_lock);
+			spin_unlock(&server->mid_queue_lock);
 			add_credits(server, &credits, 0);
 			return rc;
 		}
-		spin_unlock(&server->mid_lock);
+		spin_unlock(&server->mid_queue_lock);
 	}
 
 	rc = cifs_sync_mid_result(midQ, server);
@@ -1605,15 +1605,15 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		rc = wait_for_response(server, midQ);
 		if (rc) {
 			send_cancel(server, &rqst, midQ);
-			spin_lock(&server->mid_lock);
+			spin_lock(&server->mid_queue_lock);
 			if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
 			    midQ->mid_state == MID_RESPONSE_RECEIVED) {
 				/* no longer considered to be "in-flight" */
 				midQ->callback = release_mid;
-				spin_unlock(&server->mid_lock);
+				spin_unlock(&server->mid_queue_lock);
 				return rc;
 			}
-			spin_unlock(&server->mid_lock);
+			spin_unlock(&server->mid_queue_lock);
 		}
 
 		/* We got the response - restart system call. */