char: diag: add write done sync function

In factory mode the tty_diag module needs a spinlock
eliminated from the diag_usb_write_done call.

Change-Id: Ic7196276e1d07fa9eb5c58b2f7c35d4e24ffa9b6
Reviewed-on: https://gerrit.mot.com/1128708
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Kenneth Kessler <kennykessler@motorola.com>
Submit-Approved: Jira Key
Reviewed-on: https://gerrit.mot.com/1180282
Reviewed-by: Ling Jin <lingjin@motorola.com>
Reviewed-on: https://gerrit.mot.com/1242985
Reviewed-by: Master Yoda
Reviewed-by: Shengqi Wang <wangsq2@motorola.com>
Reviewed-by: Yuecai Liu <liuyc20@motorola.com>
Reviewed-on: https://gerrit.mot.com/1448855
Reviewed-by: Ryan Lattrel <ryanl@motorola.com>
Reviewed-on: https://gerrit.mot.com/1510727

drivers/char/diag/diag_usb.c

@@ -352,7 +352,8 @@ static void usb_read_done_work_fn(struct work_struct *work)
 }
 
 static void diag_usb_write_done(struct diag_usb_info *ch,
-				struct diag_request *req)
+				struct diag_request *req,
+				int sync)
 {
 	int ctxt = 0;
 	int len = 0;
@@ -362,14 +363,15 @@ static void diag_usb_write_done(struct diag_usb_info *ch,
 
 	if (!ch || !req)
 		return;
-
-	spin_lock_irqsave(&ch->write_lock, flags);
+	if (!sync)
+		spin_lock_irqsave(&ch->write_lock, flags);
 	ch->write_cnt++;
 	entry = diag_usb_buf_tbl_get(ch, req->context);
 	if (!entry) {
 		pr_err_ratelimited("diag: In %s, unable to find entry %pK in the table\n",
 				   __func__, req->context);
-		spin_unlock_irqrestore(&ch->write_lock, flags);
+		if (!sync)
+			spin_unlock_irqrestore(&ch->write_lock, flags);
 		return;
 	}
 	if (atomic_read(&entry->ref_count) != 0) {
@@ -377,7 +379,8 @@ static void diag_usb_write_done(struct diag_usb_info *ch,
 			 atomic_read(&entry->ref_count));
 		diag_ws_on_copy_complete(DIAG_WS_MUX);
 		diagmem_free(driver, req, ch->mempool);
-		spin_unlock_irqrestore(&ch->write_lock, flags);
+		if (!sync)
+			spin_unlock_irqrestore(&ch->write_lock, flags);
 		return;
 	}
 	DIAG_LOG(DIAG_DEBUG_MUX, "full write_done\n");
@@ -394,7 +397,8 @@ static void diag_usb_write_done(struct diag_usb_info *ch,
 	len = 0;
 	ctxt = 0;
 	diagmem_free(driver, req, ch->mempool);
-	spin_unlock_irqrestore(&ch->write_lock, flags);
+	if(!sync)
+		spin_unlock_irqrestore(&ch->write_lock, flags);
 }
 
 static void diag_usb_notifier(void *priv, unsigned int event,
@@ -439,7 +443,10 @@ static void diag_usb_notifier(void *priv, unsigned int event,
 			   &usb_info->read_done_work);
 		break;
 	case USB_DIAG_WRITE_DONE:
-		diag_usb_write_done(usb_info, d_req);
+		diag_usb_write_done(usb_info, d_req, 0);
+		break;
+	case USB_DIAG_WRITE_DONE_SYNC:
+		diag_usb_write_done(usb_info, d_req, 1);
 		break;
 	default:
 		pr_err_ratelimited("diag: Unknown event from USB diag\n");

include/linux/usb/usbdiag.h

@@ -18,6 +18,7 @@
 #define USB_DIAG_DISCONNECT	1
 #define USB_DIAG_WRITE_DONE	2
 #define USB_DIAG_READ_DONE	3
+#define USB_DIAG_WRITE_DONE_SYNC 4
 
 struct diag_request {
 	char *buf;