linux-kernel - [PATCH v6 3/7] usb: gadget: u_serial: make OBEX port not a console

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Message-Id: <15b3e89a888a24d90647dc5d93820bf5b80c9a06.1565426370.git.mirq-linux@rere.qmqm.pl>
Date:   Sat, 10 Aug 2019 10:42:50 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     linux-usb@...r.kernel.org
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 3/7] usb: gadget: u_serial: make OBEX port not a console

Prevent OBEX serial port from ever becoming a console. Console messages
will definitely break the protocol, and since you have to instantiate
the port making it explicitly for OBEX, there is no point in allowing
console to break it by mistake.

Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
  v6: rebased on balbi/testing/next
  v5: no changes
  v4: no changes
  v3: rename gserial_alloc_line_raw() -> gserial_alloc_line_no_console()
  v2: change of API
    + commit message massage

---
 drivers/usb/gadget/function/f_obex.c   |  2 +-
 drivers/usb/gadget/function/u_serial.c | 16 ++++++++++++----
 drivers/usb/gadget/function/u_serial.h |  1 +
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/function/f_obex.c b/drivers/usb/gadget/function/f_obex.c
index 55b7f57d2dc7..ab26d84ed95e 100644
--- a/drivers/usb/gadget/function/f_obex.c
+++ b/drivers/usb/gadget/function/f_obex.c
@@ -432,7 +432,7 @@ static struct usb_function_instance *obex_alloc_inst(void)
 		return ERR_PTR(-ENOMEM);
 
 	opts->func_inst.free_func_inst = obex_free_inst;
-	ret = gserial_alloc_line(&opts->port_num);
+	ret = gserial_alloc_line_no_console(&opts->port_num);
 	if (ret) {
 		kfree(opts);
 		return ERR_PTR(ret);
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 94f6999e8262..62280c23cde2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1180,7 +1180,7 @@ void gserial_free_line(unsigned char port_num)
 }
 EXPORT_SYMBOL_GPL(gserial_free_line);
 
-int gserial_alloc_line(unsigned char *line_num)
+int gserial_alloc_line_no_console(unsigned char *line_num)
 {
 	struct usb_cdc_line_coding	coding;
 	struct gs_port			*port;
@@ -1221,12 +1221,20 @@ int gserial_alloc_line(unsigned char *line_num)
 		goto err;
 	}
 	*line_num = port_num;
-
-	if (!port_num)
-		gs_console_init(port);
 err:
 	return ret;
 }
+EXPORT_SYMBOL_GPL(gserial_alloc_line_no_console);
+
+int gserial_alloc_line(unsigned char *line_num)
+{
+	int ret = gserial_alloc_line_no_console(line_num);
+
+	if (!ret && !*line_num)
+		gs_console_init(ports[*line_num].port);
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(gserial_alloc_line);
 
 /**
diff --git a/drivers/usb/gadget/function/u_serial.h b/drivers/usb/gadget/function/u_serial.h
index 9acaac1cbb75..8b472b0c8cb4 100644
--- a/drivers/usb/gadget/function/u_serial.h
+++ b/drivers/usb/gadget/function/u_serial.h
@@ -54,6 +54,7 @@ struct usb_request *gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t flags);
 void gs_free_req(struct usb_ep *, struct usb_request *req);
 
 /* management of individual TTY ports */
+int gserial_alloc_line_no_console(unsigned char *port_line);
 int gserial_alloc_line(unsigned char *port_line);
 void gserial_free_line(unsigned char port_line);
 
-- 
2.20.1