Hi,

-----Original Message-----
From: Felipe Balbi <balbi@kernel.org>
Sent: Tuesday, August 24, 2021 4:29 PM
To: Linyu Yuan (QUIC) <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; linux-
usb@vger.kernel.org
Subject: Re: [PATCH V4 1/3] usb: gadget: configfs: add UDC trace entry


Hi again,

Felipe Balbi [off-list ref] writes:

quoted

Linyu Yuan [off-list ref] writes:

quoted

add trace in function gadget_dev_desc_UDC_store()
will show when user space enable/disable the gadget.

Signed-off-by: Linyu Yuan <redacted>
---
 drivers/usb/gadget/Makefile         |  1 +
 drivers/usb/gadget/configfs.c       |  3 +++
 drivers/usb/gadget/configfs_trace.c |  7 +++++++
 drivers/usb/gadget/configfs_trace.h | 39

+++++++++++++++++++++++++++++++++++++

quoted

quoted

 4 files changed, 50 insertions(+)
 create mode 100644 drivers/usb/gadget/configfs_trace.c
 create mode 100644 drivers/usb/gadget/configfs_trace.h

diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 130dad7..8e9c2b8 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile

@@ -9,5 +9,6 @@ ccflags-y				+= -

I$(srctree)/drivers/usb/gadget/udc

quoted

quoted

 obj-$(CONFIG_USB_LIBCOMPOSITE)	+= libcomposite.o
 libcomposite-y			:= usbstring.o config.o epautoconf.o
 libcomposite-y			+= composite.o functions.o configfs.o

u_f.o

quoted

quoted

+libcomposite-y			+= configfs_trace.o

 obj-$(CONFIG_USB_GADGET)	+= udc/ function/ legacy/

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 477e72a..f7f3af8 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c

@@ -9,6 +9,7 @@
 #include "configfs.h"
 #include "u_f.h"
 #include "u_os_desc.h"
+#include "configfs_trace.h"

 int check_user_usb_string(const char *name,
 		struct usb_gadget_strings *stringtab_dev)

@@ -270,6 +271,8 @@ static ssize_t gadget_dev_desc_UDC_store(struct

config_item *item,

quoted

quoted

 	if (name[len - 1] == '\n')
 		name[len - 1] = '\0';

+	trace_gadget_dev_desc_UDC_store(config_item_name(item),

name);

quoted

why tracing only the names? This gives us no insight into whatever bug

This patch only trace user space operation when enable a composition like below of android or similar thing in another way,

on property:sys.usb.config=mtp && property:sys.usb.configfs=1
    write /config/usb_gadget/g1/configs/b.1/strings/0x409/configuration "mtp"
    symlink /config/usb_gadget/g1/functions/mtp.gs0 /config/usb_gadget/g1/configs/b.1/f1
    write /config/usb_gadget/g1/UDC ${sys.usb.controller}

quoted

may happen and we may want to use trace events to debug. Rather, try to
think of trace events as tracking the lifetime of the UDC and
gadget. Trace values that may change over time.

UDC already have trace  https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/tree/drivers/usb/gadget/udc/trace.h?h=usb-linus
I can't confirm if I understand your comment correctly ?

quoted

I also think that all three patches could be combined into a single
commit, but that's up to discussion.

nevermind this last paragraph, just saw that Greg asked you to split ;-)

The first paragraph remains valid, though

--
balbi