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usb: gadget: u_serial: diagnose missed console messages

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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 <mirq-linux@rere.qmqm.pl>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Michał Mirosław 2019-08-10 10:42:52 +02:00 committed by Felipe Balbi
parent bd25a14edb
commit ef9b457d0d
1 changed files with 14 additions and 1 deletions
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15
drivers/usb/gadget/function/u_serial.c
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@ -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);