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Commit 219bb89b authored by Vamsi Krishna's avatar Vamsi Krishna
Browse files

ks_bridge: Use cdev interface instead of misc interface 



Using misc device interface may result in deadlock if two drivers
are trying to open/close/register/unregister misc devices
simultaneously. Deadlock is observed when one driver is blocked on
open and another dependent driver is trying to unregister misc
device. To avoid such issues use cdev interface to expose character
device

Change-Id: I5e4a20846027875b0d1556cc28d773968dd0819c
Signed-off-by: default avatarVamsi Krishna <vskrishn@codeaurora.org>
parent 8f583bb6

drivers/usb/misc/ks_bridge.c

+75 −39
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ 
#include <linux/usb.h>

#include <linux/debugfs.h>

#include <linux/seq_file.h>

#include <linux/miscdevice.h>

#include <linux/cdev.h>

#include <linux/list.h>

#include <linux/wait.h>
@@ -68,6 +68,10 @@ struct data_pkt { 
#define MAX_DATA_PKT_SIZE	16384

#define PENDING_URB_TIMEOUT	10



struct ksb_dev_info {

	const char *name;

};



struct ks_bridge {

	char			*name;

	spinlock_t		lock;
@@ -78,10 +82,17 @@ struct ks_bridge { 
	struct list_head	to_ks_list;

	wait_queue_head_t	ks_wait_q;

	wait_queue_head_t	pending_urb_wait;

	struct miscdevice	fs_dev;

	atomic_t		tx_pending_cnt;

	atomic_t		rx_pending_cnt;



	struct ksb_dev_info	id_info;



	/* cdev interface */

	dev_t			cdev_start_no;

	struct cdev		cdev;

	struct class		*class;

	struct device		*device;



	/* usb specific */

	struct usb_device	*udev;

	struct usb_interface	*ifc;
@@ -198,7 +209,7 @@ read_start: 


		ret = copy_to_user(buf + copied, pkt->buf + pkt->n_read, len);

		if (ret) {

			dev_err(ksb->fs_dev.this_device,

			dev_err(ksb->device,

					"copy_to_user failed err:%d\n", ret);

			ksb_free_data_pkt(pkt);

			return -EFAULT;
@@ -232,7 +243,7 @@ read_start: 


	dbg_log_event(ksb, "KS_READ", copied, 0);



	dev_dbg(ksb->fs_dev.this_device, "count:%d space:%d copied:%d", count,

	dev_dbg(ksb->device, "count:%d space:%d copied:%d", count,

			space, copied);



	return copied;
@@ -251,7 +262,7 @@ static void ksb_tx_cb(struct urb *urb) 


	if (urb->status < 0)

		pr_err_ratelimited("%s: urb failed with err:%d",

				ksb->fs_dev.name, urb->status);

				ksb->id_info.name, urb->status);



	ksb_free_data_pkt(pkt);
@@ -278,7 +289,7 @@ static void ksb_tomdm_work(struct work_struct *w) 
		urb = usb_alloc_urb(0, GFP_KERNEL);

		if (!urb) {

			pr_err_ratelimited("%s: unable to allocate urb",

					ksb->fs_dev.name);

					ksb->id_info.name);

			ksb_free_data_pkt(pkt);

			return;

		}
@@ -286,7 +297,7 @@ static void ksb_tomdm_work(struct work_struct *w) 
		ret = usb_autopm_get_interface(ksb->ifc);

		if (ret < 0 && ret != -EAGAIN && ret != -EACCES) {

			pr_err_ratelimited("%s: autopm_get failed:%d",

					ksb->fs_dev.name, ret);

					ksb->id_info.name, ret);

			usb_free_urb(urb);

			ksb_free_data_pkt(pkt);

			return;
@@ -333,14 +344,14 @@ static ssize_t ksb_fs_write(struct file *fp, const char __user *buf, 


	pkt = ksb_alloc_data_pkt(count, GFP_KERNEL, ksb);

	if (IS_ERR(pkt)) {

		dev_err(ksb->fs_dev.this_device,

		dev_err(ksb->device,

				"unable to allocate data packet");

		return PTR_ERR(pkt);

	}



	ret = copy_from_user(pkt->buf, buf, count);

	if (ret) {

		dev_err(ksb->fs_dev.this_device,

		dev_err(ksb->device,

				"copy_from_user failed: err:%d", ret);

		ksb_free_data_pkt(pkt);

		return ret;
@@ -357,15 +368,15 @@ static ssize_t ksb_fs_write(struct file *fp, const char __user *buf, 


static int ksb_fs_open(struct inode *ip, struct file *fp)

{

	struct miscdevice *mdev = fp->private_data;

	struct ks_bridge *ksb = container_of(mdev, struct ks_bridge, fs_dev);

	struct ks_bridge *ksb =

			container_of(ip->i_cdev, struct ks_bridge, cdev);



	if (IS_ERR(ksb)) {

		pr_err("ksb device not found");

		return -ENODEV;

	}



	dev_dbg(ksb->fs_dev.this_device, ":%s", ksb->fs_dev.name);

	dev_dbg(ksb->device, ":%s", ksb->id_info.name);

	dbg_log_event(ksb, "FS-OPEN", 0, 0);



	fp->private_data = ksb;
@@ -381,7 +392,7 @@ static int ksb_fs_release(struct inode *ip, struct file *fp) 
{

	struct ks_bridge	*ksb = fp->private_data;



	dev_dbg(ksb->fs_dev.this_device, ":%s", ksb->fs_dev.name);

	dev_dbg(ksb->device, ":%s", ksb->id_info.name);

	dbg_log_event(ksb, "FS-RELEASE", 0, 0);



	clear_bit(FILE_OPENED, &ksb->flags);
@@ -398,37 +409,21 @@ static const struct file_operations ksb_fops = { 
	.release = ksb_fs_release,

};



static struct miscdevice ksb_fboot_dev[] = {

static struct ksb_dev_info ksb_fboot_dev[] = {

	{

		.minor = MISC_DYNAMIC_MINOR,

		.name = "ks_hsic_bridge",

		.fops = &ksb_fops,

	},

	{

		.minor = MISC_DYNAMIC_MINOR,

		.name = "ks_usb_bridge",

		.fops = &ksb_fops,

	},

};



static const struct file_operations efs_fops = {

	.owner = THIS_MODULE,

	.read = ksb_fs_read,

	.write = ksb_fs_write,

	.open = ksb_fs_open,

	.release = ksb_fs_release,

};



static struct miscdevice ksb_efs_hsic_dev = {

	.minor = MISC_DYNAMIC_MINOR,

static struct ksb_dev_info ksb_efs_hsic_dev = {

	.name = "efs_hsic_bridge",

	.fops = &efs_fops,

};



static struct miscdevice ksb_efs_usb_dev = {

	.minor = MISC_DYNAMIC_MINOR,

static struct ksb_dev_info ksb_efs_usb_dev = {

	.name = "efs_usb_bridge",

	.fops = &efs_fops,

};

static const struct usb_device_id ksb_usb_ids[] = {

	{ USB_DEVICE_INTERFACE_NUMBER(0x5c6, 0x9008, 0),
@@ -518,7 +513,7 @@ static void ksb_rx_cb(struct urb *urb) 
		if (urb->status != -ESHUTDOWN && urb->status != -ENOENT

				&& urb->status != -EPROTO)

			pr_err_ratelimited("%s: urb failed with err:%d",

					ksb->fs_dev.name, urb->status);

					ksb->id_info.name, urb->status);

		ksb_free_data_pkt(pkt);

		goto done;

	}
@@ -555,7 +550,7 @@ static void ksb_start_rx_work(struct work_struct *w) 
	if (ret < 0) {

		if (ret != -EAGAIN && ret != -EACCES) {

			pr_err_ratelimited("%s: autopm_get failed:%d",

					ksb->fs_dev.name, ret);

					ksb->id_info.name, ret);

			return;

		}

		put = false;
@@ -613,14 +608,15 @@ ksb_usb_probe(struct usb_interface *ifc, const struct usb_device_id *id) 
	struct ks_bridge		*ksb;

	unsigned long			flags;

	struct data_pkt			*pkt;

	struct miscdevice		*mdev, *fbdev;

	struct ksb_dev_info		*mdev, *fbdev;

	struct usb_device		*udev;

	unsigned int			bus_id;

	int ret;



	ifc_num = ifc->cur_altsetting->desc.bInterfaceNumber;



	udev = interface_to_usbdev(ifc);

	fbdev = mdev = (struct miscdevice *)id->driver_info;

	fbdev = mdev = (struct ksb_dev_info *)id->driver_info;



	bus_id = str_to_busid(udev->bus->bus_name);

	if (bus_id == BUS_UNDEF) {
@@ -658,6 +654,7 @@ ksb_usb_probe(struct usb_interface *ifc, const struct usb_device_id *id) 
	ksb->udev = usb_get_dev(interface_to_usbdev(ifc));

	ksb->ifc = ifc;

	ifc_desc = ifc->cur_altsetting;

	ksb->id_info = *mdev;



	for (i = 0; i < ifc_desc->desc.bNumEndpoints; i++) {

		ep_desc = &ifc_desc->endpoint[i].desc;
@@ -703,8 +700,33 @@ ksb_usb_probe(struct usb_interface *ifc, const struct usb_device_id *id) 
	}

	spin_unlock_irqrestore(&ksb->lock, flags);



	ksb->fs_dev = *mdev;

	misc_register(&ksb->fs_dev);

	ret = alloc_chrdev_region(&ksb->cdev_start_no, 0, 1, mdev->name);

	if (ret < 0) {

		dbg_log_event(ksb, "chr reg failed", ret, 0);

		goto fail_chrdev_region;

	}



	ksb->class = class_create(THIS_MODULE, mdev->name);

	if (IS_ERR(ksb->class)) {

		dbg_log_event(ksb, "clscr failed", PTR_ERR(ksb->class), 0);

		goto fail_class_create;

	}



	cdev_init(&ksb->cdev, &ksb_fops);

	ksb->cdev.owner = THIS_MODULE;



	ret = cdev_add(&ksb->cdev, ksb->cdev_start_no, 1);

	if (ret < 0) {

		dbg_log_event(ksb, "cdev_add failed", ret, 0);

		goto fail_class_create;

	}



	ksb->device = device_create(ksb->class, NULL, ksb->cdev_start_no,

				NULL, mdev->name);

	if (IS_ERR(ksb->device)) {

		dbg_log_event(ksb, "devcrfailed", PTR_ERR(ksb->device), 0);

		goto fail_device_create;

	}



	if (device_can_wakeup(&ksb->udev->dev)) {

		ifc->needs_remote_wakeup = 1;
@@ -714,6 +736,17 @@ ksb_usb_probe(struct usb_interface *ifc, const struct usb_device_id *id) 
	dev_dbg(&udev->dev, "usb dev connected");



	return 0;



fail_device_create:

	cdev_del(&ksb->cdev);

fail_class_create:

	unregister_chrdev_region(ksb->cdev_start_no, 1);

fail_chrdev_region:

	usb_set_intfdata(ifc, NULL);

	clear_bit(USB_DEV_CONNECTED, &ksb->flags);



	return -ENODEV;



}



static int ksb_usb_suspend(struct usb_interface *ifc, pm_message_t message)
@@ -767,7 +800,10 @@ static void ksb_usb_disconnect(struct usb_interface *ifc) 
	cancel_work_sync(&ksb->to_mdm_work);

	cancel_work_sync(&ksb->start_rx_work);



	misc_deregister(&ksb->fs_dev);

	device_destroy(ksb->class, ksb->cdev_start_no);

	cdev_del(&ksb->cdev);

	class_destroy(ksb->class);

	unregister_chrdev_region(ksb->cdev_start_no, 1);



	usb_kill_anchored_urbs(&ksb->submitted);