Re: [PATCH v3 4/6] usb: gadget: f_fs: add a device reference of usb_gadget->dev

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On 3/29/2023 3:31 PM, Greg Kroah-Hartman wrote:
On Wed, Mar 29, 2023 at 03:00:54PM +0800, Linyu Yuan wrote:
On 3/29/2023 2:53 PM, Greg Kroah-Hartman wrote:
On Mon, Mar 27, 2023 at 06:12:18PM +0800, Linyu Yuan wrote:
It is known that dev_vdbg() macro can accept NULL or non-NULL dev pointer.

Add a struct device *dev member in struct ffs_data, set it to NULL before
binding or after unbinding to a usb_gadget, set it reference of usb_gadget
->dev when bind success.

Then it can help replace private pr_vdebug() to dev_vdbg() consistently.

Signed-off-by: Linyu Yuan <quic_linyyuan@xxxxxxxxxxx>
v3: new patch in this version

   drivers/usb/gadget/function/f_fs.c | 3 +++
   drivers/usb/gadget/function/u_fs.h | 1 +
   2 files changed, 4 insertions(+)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index a4051c8..25461f1 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -1722,6 +1722,7 @@ static struct ffs_data *ffs_data_new(const char *dev_name)
   		return NULL;
+	ffs->dev = NULL;
   	refcount_set(&ffs->ref, 1);
   	atomic_set(&ffs->opened, 0);
   	ffs->state = FFS_READ_DESCRIPTORS;
@@ -1831,6 +1832,7 @@ static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev)
   	ffs->gadget = cdev->gadget;
+	ffs->dev = &cdev->gadget->dev;
   	return 0;
@@ -1843,6 +1845,7 @@ static void functionfs_unbind(struct ffs_data *ffs)
   		usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req);
   		ffs->ep0req = NULL;
+		ffs->dev = NULL;
   		ffs->gadget = NULL;
   		clear_bit(FFS_FL_BOUND, &ffs->flags);
diff --git a/drivers/usb/gadget/function/u_fs.h b/drivers/usb/gadget/function/u_fs.h
index 4b3365f..c5f6167 100644
--- a/drivers/usb/gadget/function/u_fs.h
+++ b/drivers/usb/gadget/function/u_fs.h
@@ -146,6 +146,7 @@ enum ffs_setup_state {
   struct ffs_data {
   	struct usb_gadget		*gadget;
+	struct device			*dev;
No, sorry, this is not correct.

You already have a struct device right there in the struct usb_gadget.
Use that one instead, as you are just setting this pointer to the same
value (see above where you set it.)

just want to use consistent dev_(v)dbg() related macro, to avoid reference

when usb_gadget is NULL.
When will usb_gadget be NULL when you want to print out logging
messages?  You shouldn't be printing out anything during that time
anyway, right?

when usb_gadget is NULL, there could be debug message because user space application

can start configure the ffs instance (like adb ...) for USB interface/endpoint/string descriptor.

as dev_dbg related macro is safe to accept NULL, there is no need find out when will

usb_gadget is NULL and when will it a valid pointer.


greg k-h

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