From ffed60971f3d95923b99ea970862c6ab6a22c20f Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 25 Jun 2019 16:03:58 -0400 Subject: USB: core: Remove usbfs_mutex Commit 4a2a8a2cce86 ("usbfs: private mutex for open, release, and remove") is now obsolete. The commit was created back when we had to handle both usbfs device nodes and the old usbdevfs filesystem (/proc/bus/usb/), but usbdevfs no longer exists. This means there's no longer any need to hold a mutex during two separate removal operations (and thus during an entire notifier chain call). Furthermore, the one remaining remove/release pair doesn't race with open thanks to the synchronization provided by the device model core in bus_find_device(). Remove and release don't race with each other because they both run with the device lock held. The upshot is that usbfs_mutex isn't needed any more. This patch removes it entirely. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/devio.c | 9 --------- drivers/usb/core/notify.c | 3 --- drivers/usb/core/usb.h | 1 - 3 files changed, 13 deletions(-) (limited to 'drivers/usb/core') diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 186790b06b11..0100a54165cd 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -48,9 +48,6 @@ #define USB_DEVICE_MAX (USB_MAXBUS * 128) #define USB_SG_SIZE 16384 /* split-size for large txs */ -/* Mutual exclusion for removal, open, and release */ -DEFINE_MUTEX(usbfs_mutex); - struct usb_dev_state { struct list_head list; /* state list */ struct usb_device *dev; @@ -979,15 +976,9 @@ static int usbdev_open(struct inode *inode, struct file *file) ret = -ENODEV; - /* Protect against simultaneous removal or release */ - mutex_lock(&usbfs_mutex); - /* usbdev device-node */ if (imajor(inode) == USB_DEVICE_MAJOR) dev = usbdev_lookup_by_devt(inode->i_rdev); - - mutex_unlock(&usbfs_mutex); - if (!dev) goto out_free_ps; diff --git a/drivers/usb/core/notify.c b/drivers/usb/core/notify.c index ab474b11523e..e6143663778f 100644 --- a/drivers/usb/core/notify.c +++ b/drivers/usb/core/notify.c @@ -53,11 +53,8 @@ void usb_notify_add_device(struct usb_device *udev) void usb_notify_remove_device(struct usb_device *udev) { - /* Protect against simultaneous usbfs open */ - mutex_lock(&usbfs_mutex); blocking_notifier_call_chain(&usb_notifier_list, USB_DEVICE_REMOVE, udev); - mutex_unlock(&usbfs_mutex); } void usb_notify_add_bus(struct usb_bus *ubus) diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h index d95a5358f73d..bd8d01f85a13 100644 --- a/drivers/usb/core/usb.h +++ b/drivers/usb/core/usb.h @@ -169,7 +169,6 @@ extern const struct attribute_group *usb_device_groups[]; extern const struct attribute_group *usb_interface_groups[]; /* usbfs stuff */ -extern struct mutex usbfs_mutex; extern struct usb_driver usbfs_driver; extern const struct file_operations usbfs_devices_fops; extern const struct file_operations usbdev_file_operations; -- cgit v1.2.3-59-g8ed1b