linux-kernel - [PATCH 3/6] USB: gadget: f_hid: find f

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Message-Id: <20191024164538.3161474-4-john@metanate.com>
Date:   Thu, 24 Oct 2019 17:45:35 +0100
From:   John Keeping <john@...anate.com>
To:     linux-usb@...r.kernel.org
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, John Keeping <john@...anate.com>
Subject: [PATCH 3/6] USB: gadget: f_hid: find f_hidg by IDR lookup on open

As a step towards decoupling the cdev lifetime from f_hidg, lookup the
f_hidg structure by minor number from IDR when opening the device.

Signed-off-by: John Keeping <john@...anate.com>
---
 drivers/usb/gadget/function/f_hid.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index 838256086bd2..4d20347fe908 100644
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -441,8 +441,14 @@ static int f_hidg_release(struct inode *inode, struct file *fd)
 
 static int f_hidg_open(struct inode *inode, struct file *fd)
 {
-	struct f_hidg *hidg =
-		container_of(inode->i_cdev, struct f_hidg, cdev);
+	struct f_hidg *hidg;
+
+	mutex_lock(&hidg_idr_lock);
+	hidg = idr_find(&hidg_idr, iminor(inode));
+	mutex_unlock(&hidg_idr_lock);
+
+	if (!hidg)
+		return -ENODEV;
 
 	fd->private_data = hidg;
 
@@ -827,6 +833,10 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
 	if (status)
 		goto fail_free_descs;
 
+	mutex_lock(&hidg_idr_lock);
+	idr_replace(&hidg_idr, hidg, hidg->minor);
+	mutex_unlock(&hidg_idr_lock);
+
 	device = device_create(hidg_class, NULL, dev, NULL,
 			       "%s%d", "hidg", hidg->minor);
 	if (IS_ERR(device)) {
-- 
2.23.0