[v2,5/5] usb: gadget: u_serial: diagnose missed console messages

[v2,5/5] usb: gadget: u_serial: diagnose missed console messages

[Greg Kroah-Hartman]

On Wed, Feb 27, 2019 at 10:29:39AM +0100, Michał Mirosław wrote:
> Insert markers in console stream marking places where data
> is missing. This makes the hole in the data stand out clearly
> instead of glueing together unrelated messages.
> 
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> ---
>   v2: commit message massage

Provide an example of that what "marker" looks like in the commit log
text?  That would be nice to see...

thanks,

greg k-h

[v2,5/5] usb: gadget: u_serial: diagnose missed console messages

[Michał Mirosław]

Insert markers in console stream marking places where data
is missing. This makes the hole in the data stand out clearly
instead of glueing together unrelated messages.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
---
  v2: commit message massage
---
 drivers/usb/gadget/function/u_serial.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 604e187fadb7..66518aba58c2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -88,6 +88,7 @@ struct gs_console {
 	spinlock_t		lock;
 	struct usb_request	*req;
 	struct kfifo		buf;
+	size_t			missed;
 };
 
 /*
@@ -930,6 +931,15 @@ static void __gs_console_push(struct gs_console *cons)
 	if (!size)
 		return;
 
+	if (cons->missed && ep->maxpacket >= 64) {
+		char buf[64];
+		size_t len;
+
+		len = sprintf(buf, "\n[MISSED %zu bytes]\n", cons->missed);
+		kfifo_in(&cons->buf, buf, len);
+		cons->missed = 0;
+	}
+
 	req->length = size;
 	if (usb_ep_queue(ep, req, GFP_ATOMIC))
 		req->length = 0;
@@ -951,10 +961,13 @@ static void gs_console_write(struct console *co,
 {
 	struct gs_console *cons = container_of(co, struct gs_console, console);
 	unsigned long flags;
+	size_t n;
 
 	spin_lock_irqsave(&cons->lock, flags);
 
-	kfifo_in(&cons->buf, buf, count);
+	n = kfifo_in(&cons->buf, buf, count);
+	if (n < count)
+		cons->missed += count - n;
 
 	if (cons->req && !cons->req->length)
 		schedule_work(&cons->work);