simultaneously detaching kernel drivers on the same USB device we can
get stuck in the "usb_wait_pending_ref_locked()" function because the
conditions needed for allowing detach are not met. The "destroy_dev()"
function waits for all system calls involving the given character
device to return. Character device system calls may lock the USB
enumeration lock, which is also held when "destroy_dev()" is
called. This can sometimes lead to a deadlock not noticed by
WITNESS. The current solution is to ensure the calling thread is the
only one holding the USB enumeration lock and prevent other threads
from getting refs while a USB device detach is ongoing. This turned
out not to be sufficient. To solve this deadlock we could use
"destroy_dev_sched()" to schedule the device destruction in the
background, but then we don't know when it is safe to free() the
private data of the character device. Instead a callback function is
executed by the USB explore process to kill off any leftover USB
character devices synchronously after the USB device explore code is
finished and the USB enumeration lock is no longer locked. This makes
porting easier and also ensures us that character devices must
eventually go away after a USB device detach.
While at it ensure that "flag_iserror" is only written when "priv_mtx"
is locked, which is protecting it.
MFC after: 5 days
- Implement support for interrupt filters in the DWC OTG driver, to
reduce the amount of CPU task switching when only feeding the FIFOs.
- Add common spinlock to the USB bus structure.
MFC after: 2 weeks
so that simultaneous access cannot happen. Protect scratch area using
the enumeration lock. Also reduce stack usage in usbd_transfer_setup()
by moving some big stack members to the scratch area. This saves around
200 bytes of stack.
- Fix a whitespace.
MFC after: 1 week
This patch should remove the need for kldunload of USB
controller drivers at suspend and kldload of USB controller
drivers at resume.
This patch also fixes some build issues in avr32dci.c
MFC after: 2 weeks
packets which go through each USB host controllers. Its implementations
are almost based on BPF code and very similar with it except it's
little bit customized for USB packet only. The userland program
usbdump(8) would be committed soon.
Discussed with: hps, thompsa, yongari
Change the roothub exec functions to take the usb request and data pointers
directly rather than placing them on the parent bus struct.
Submitted by: Hans Petter Selasky
Refactor how we interface with the root HUB. This is achieved by making a
direct call from usb2_do_request to the host controller for root hub requests,
this call will perform the controller specific register read/writes and return
the error code.
This cuts out a lot of code in the host controller files and saves one thread
per USB bus.
Submitted by: Hans Petter Selasky
Refactor how we interface with the root HUB. This cuts around 1200 lines of
code totally and saves one thread per USB bus.
Submitted by: Hans Petter Selasky
the devfs clone handler to open the (invisible) devices on the fly.
The /dev entries are layed out as follows,
/dev/usbctl = master device
/dev/usb/0.1.0.5 = usb device, (<bus>.<dev>.<iface>.<endpoint>)
/dev/ugen0.1 -> usb/0.1.0.0 = ugen link to ctrl endpoint
This also removes the custom permissions model from USB. Bump
__FreeBSD_version to 800066.
Submitted by: rink (earlier version)