diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2019-06-25 16:03:58 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-26 10:28:09 +0800 |
| commit | ffed60971f3d95923b99ea970862c6ab6a22c20f (patch) | |
| tree | 295db5fee660d10d63a36be83f17f434bc0bc58c | |
| parent | 58ee01007c9e00531c1280b2d99b49d29a5e9844 (diff) | |
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 <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/core/devio.c | 9 | ||||
| -rw-r--r-- | drivers/usb/core/notify.c | 3 | ||||
| -rw-r--r-- | drivers/usb/core/usb.h | 1 |
3 files changed, 0 insertions, 13 deletions
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; |