diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-21 10:51:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-21 10:51:03 -0700 |
| commit | 8b108c609adefd98577c35f0a41497a610041a6c (patch) | |
| tree | f1552fdc5bf0ebcc484a88f01cd3864113adf25c /drivers/hid/usbhid/hiddev.c | |
| parent | 7ce1418f95e918cfc5ad36e3ec3431145c768cd0 (diff) | |
| parent | 73d5e8f77e88a4d3a154dfdbb4ed2cf461b7bf21 (diff) | |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid: (59 commits)
HID: fix up 'EMBEDDED' mess in Kconfig
HID: roccat: cleanup preprocessor macros
HID: roccat: refactor special event handling
HID: roccat: fix special button support
HID: roccat: Correctly mark init and exit functions
HID: hidraw: Use Interrupt Endpoint for OUT Transfers if Available
HID: hid-samsung: remove redundant key mappings
HID: add omitted hid-zydacron.c file
HID: hid-samsung: add support for Creative Desktop Wireless 6000
HID: picolcd: Eliminate use after free
HID: Zydacron Remote Control driver
HID: Use kmemdup
HID: magicmouse: fix input registration
HID: make Prodikeys driver standalone config option
HID: Prodikeys PC-MIDI HID Driver
HID: hidraw: fix indentation
HID: ntrig: add filtering module parameters
HID: ntrig: add sysfs access to filter parameters
HID: ntrig: add sensitivity and responsiveness support
HID: add multi-input quirk for eGalax Touchcontroller
...
Diffstat (limited to 'drivers/hid/usbhid/hiddev.c')
| -rw-r--r-- | drivers/hid/usbhid/hiddev.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index 433602aed468..c24d2fa3e3b6 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -267,6 +267,7 @@ static int hiddev_open(struct inode *inode, struct file *file) struct hiddev_list *list; int res, i; + /* See comment in hiddev_connect() for BKL explanation */ lock_kernel(); i = iminor(inode) - HIDDEV_MINOR_BASE; @@ -894,8 +895,22 @@ int hiddev_connect(struct hid_device *hid, unsigned int force) hiddev->hid = hid; hiddev->exist = 1; - /* when lock_kernel() usage is fixed in usb_open(), - * we could also fix it here */ + /* + * BKL here is used to avoid race after usb_register_dev(). + * Once the device node has been created, open() could happen on it. + * The code below will then fail, as hiddev_table hasn't been + * updated. + * + * The obvious fix -- introducing mutex to guard hiddev_table[] + * doesn't work, as usb_open() and usb_register_dev() both take + * minor_rwsem, thus we'll have ABBA deadlock. + * + * Before BKL pushdown, usb_open() had been acquiring it in right + * order, so _open() was safe to use it to protect from this race. + * Now the order is different, but AB-BA deadlock still doesn't occur + * as BKL is dropped on schedule() (i.e. while sleeping on + * minor_rwsem). Fugly. + */ lock_kernel(); retval = usb_register_dev(usbhid->intf, &hiddev_class); if (retval) { |