From ef9b457d0dd2438b492d773c9e98c3d1bd9ec037 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Micha=C5=82=20Miros=C5=82aw?= Date: Sat, 10 Aug 2019 10:42:52 +0200 Subject: [PATCH] usb: gadget: u_serial: diagnose missed console messages MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. Example output as seen from USB host side: [ 0.064078] pinctrl core: registered pin 16 (UART3_RTS_N PC0) on 70000868.pinmux [ 0.064130] pinctrl [missed 114987 bytes] [ 4.302299] udevd[134]: starting version 3.2.5 [ 4.306845] random: udevd: uninitialized urandom read (16 bytes read) Signed-off-by: Michał Mirosław Reviewed-by: Greg Kroah-Hartman Signed-off-by: Felipe Balbi --- 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 0da00546006fb..a248ed0fd5d2a 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; }; /* @@ -931,6 +932,15 @@ 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; @@ -952,10 +962,13 @@ 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); -- 2.30.2