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In usbfs's fs_remove_file() function, the aim is to remove a file or directory from usbfs. This is done by first taking the i_mutex of the parent directory of this file/dir via mutex_lock(&parent->d_inode->i_mutex); and then to call either usbfs_rmdir() for a directory or usbfs_unlink() for a file. Both these functions then take the i_mutex for the to-be-removed object themselves: mutex_lock(&inode->i_mutex); This is a classical parent->child locking order relationship that the VFS uses all over the place; the VFS locking rule is "you need to take the parent first". This patch annotates the usbfs code to make this explicit and thus informs the lockdep code that those two locks indeed have this relationship. The rules for unlink that we already use in the VFS for unlink are to use I_MUTEX_PARENT for the parent directory, and a normal mutex for the file itself; this patch follows that convention. Has no effect on non-lockdep kernels. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> |
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| usb-skeleton.c | ||
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("khubd").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.