Commits · 214ac7a0771d95d2f66d01bca5afeb2c9e8ac3c8 · nexedi / linux

25 Mar, 2013 17 commits

USB: EHCI: improve end_unlink_async() · 214ac7a0

Alan Stern authored Mar 22, 2013

This patch (as1665) changes the way ehci-hcd's end_unlink_async()
routine works in order to avoid recursive execution and to be more
efficient:

	Now when an IAA cycle ends, a new one gets started up right
	away (if it is needed) instead of waiting until the
	just-unlinked QH has been processed.

	The async_iaa list is renamed to async_idle, which better
	expresses its new purpose: It is now the list of QHs which are
	now completely idle and are waiting to be processed by
	end_unlink_async().

	A new flag is added to track whether an IAA cycle is in
	progress, because the list formerly known as async_iaa no
	longer stores the QHs waiting for the IAA to finish.

	The decision about how many QHs to process when an IAA cycle
	ends is now made at the end of the cycle, when we know the
	current state of the hardware, rather than at the beginning.
	This means a bunch of logic got moved from start_iaa_cycle()
	to end_unlink_async().
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

214ac7a0

USB: EHCI: convert singly-linked lists to list_heads · 6e018751

Alan Stern authored Mar 22, 2013

This patch (as1664) converts ehci-hcd's async_unlink, async_iaa, and
intr_unlink from singly-linked lists to standard doubly-linked
list_heads. Originally it didn't seem necessary to use list_heads,
because items are always added to and removed from these lists in FIFO
order. But now with more list processing going on, it's easier to use
the standard routines than continue with a roll-your-own approach.

I don't know if the code ends up being notably shorter, but the
patterns will be more familiar to any kernel hacker.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

6e018751

USB: EHCI: consolidate code in ehci_urb_dequeue() · 7655e316

Alan Stern authored Mar 22, 2013

This patch (as1668) consolidates two nearly identical code paths in
ehci_urb_dequeue().  The test for !qh can be removed because it will
never succeed; the fact that usb_hcd_check_unlink_urb() returned 0
means that urb must be queued and therefore urb->hcpriv must point to
a QH.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

7655e316

USB: EHCI: split needs_rescan into two flags · 7bc782d7

Alan Stern authored Mar 22, 2013

This patch (as1662) does some more QH-related cleanup in ehci-hcd.
The qh->needs_rescan flag is currently used for two different
purposes; the patch replaces it with two separate flags for greater
clarity: qh->dequeue_during_giveback indicates that a completion
handler dequeued an URB (implying that a rescan is needed), and
qh->exception indicates that the QH is in an exceptional state
requiring an unlink (either it encountered an I/O error or an unlink
was requested).

The new flags get set where the dequeue, exception, or unlink request
occurred, rather than where the unlink is started.  This is so that in
the future, if we need to, we will be able to tell apart unlinks that
truly were required from those that were carried out merely because
the QH wasn't being used.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

7bc782d7

USB: EHCI: change return value of qh_completions() · 79bcf7b0

Alan Stern authored Mar 22, 2013

This patch (as1658) cleans up the usage of qh_completions() in
ehci-hcd.  Currently the function's return value indicates whether any
URBs were given back; the idea was that the caller can scan the QH
over again to handle any URBs that were dequeued by a completion
handler.  This is not necessary; when qh_completions() is ready to
give back dequeued URBs, it does its own rescanning.

Therefore the new return value will be a flag indicating whether the
caller needs to unlink the QH.  This is more convenient than forcing
the caller to check qh->needs_rescan, and it makes a lot more sense --
why should "needs_rescan" imply that an unlink is needed?  The callers
are also changed to remove the unneeded rescans.

Lastly, the check for whether qh->qtd_list is non-empty is removed
from the start of qh_completions().  Two of the callers have to make
this test anyway, so the same test can simply be added to the other
two callers.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

79bcf7b0

USB: EHCI: changes related to qh_refresh() · c1fdb68e

Alan Stern authored Mar 22, 2013

This patch (as1638) makes several changes to the ehci-hcd driver, all
related to the qh_refresh() function.  This function must be called
whenever an idle QH gets linked back into either the async or the
periodic schedule.

	Change a BUG_ON() in the qh_update routine to a WARN_ON().
	Since this code runs in atomic context, a BUG_ON() would
	immediately freeze the whole system.

	Remove two unneeded calls to qh_refresh(), one when a QH is
	initialized and one when a QH becomes idle.  Adjust the
	adjacent comments accordingly.

	Move the qh_refresh() and qh_link_periodic() calls for new
	interrupt URBs to after the new TDs have been added.

	As a result of the previous two changes, qh_refresh() is never
	called when the qtd_list is empty.  The corresponding check in
	qh_refresh() can be removed, along with an indentation level.

These changes should not cause any alteration of behavior.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

c1fdb68e

USB: usb-skeleton.c: fix blocked forever in skel_read · c79041a4

Du Xing authored Mar 20, 2013

In skel_read,the reader blocked in wait_for_completion before submit
bulk in urb.
Using processed_urb is for retaining the completion in the case that
previous interruptible wait in skel_read was interrupted and complete
before next skel_read.  Replacing completion with waitqueue can avoid
working around the counting nature of completions
and fix the bug.

Signed-off-by: Du Xing duxing2007@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

c79041a4

USB: cdc-wdm: implement IOCTL_WDM_MAX_COMMAND · 3edce1cf

Bjørn Mork authored Mar 17, 2013

Userspace applications need to know the maximum supported message
size.

The cdc-wdm driver translates between a character device stream
and a message based protocol.  Each message is transported as a
usb control message with no further encapsulation or syncronization.
Each read or write on the character device should translate to
exactly one usb control message to ensure that message boundaries
are kept intact.  That means that the userspace application must
know the maximum message size supported by the device and driver,
making this size a vital part of the cdc-wdm character device API.

CDC WDM and CDC MBIM functions export the maximum supported
message size through CDC functional descriptors.  The cdc-wdm and
cdc_mbim drivers will parse these descriptors and use the value
chosen by the device.  The only current way for a userspace
application to retrive the value is by duplicating the descriptor
parsing. This is an unnecessary complex task, and application
writers are likely to postpone it, using a fixed value and adding
a "todo" item.

QMI functions have no way to tell the host what message size they
support.  The qmi_wwan driver use a fixed value based on protocol
recommendations and observed device behaviour.  Userspace
applications must know and hard code the same value.  This scheme
will break if we ever encounter a QMI device needing a device
specific message size quirk.  We are currently unable to support
such a device because using a non default size would break the
implicit userspace API.

The message size is currently a hidden attribute of the cdc-wdm
userspace API.  Retrieving it is unnecessarily complex, increasing
the possibility of drivers and applications using different limits.
The resulting errors are hard to debug, and can only be replicated
on identical hardware.

Exporting the maximum message size from the driver simplifies the
task for the userspace application, and creates a unified
information source independent of device and function class. It also
serves to document that the message size is part of the cdc-wdm
userspace API.

This proposed API extension has been presented for the authors of
userspace applications and libraries using the current API: libmbim,
libqmi, uqmi, oFono and ModemManager.  The replies were:

Aleksander Morgado:
 "We do really need max message size for MBIM; and as you say, it may be
  good to have the max message size info also for QMI, so the new ioctl
  seems a good addition. So +1 from my side, for what it's worth."

Dan Williams:
 "Yeah, +1 here.  I'd prefer the sysfs file, but the fact that that
  doesn't work for fd passing pretty much kills it."

No negative replies are so far received.

Cc: Aleksander Morgado <aleksander@lanedo.com>
Cc: Dan Williams <dcbw@redhat.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3edce1cf

USB: hub: Avoid NULL pointer dereference when hub doesn't have any ports · 769d7368

David Linares authored Mar 25, 2013

Return an error if hub->descriptor->bNbrPorts==0. Without this additional
check, we can end up doing a "hub->ports = kzalloc(0, GFP_KERNEL)".
This hub->ports pointer will therefore be non-NULL and will be used.
Example of dmesg:
   INIT: usb 1-1: New USB device found, idVendor=0424, idProduct=2512
   usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
   hub 1-1:1.0: USB hub found
   version 2.86 bootinghub 1-1:1.0: 0 ports detected
   Unable to handle kernel NULL pointer dereference at virtual address 00000010
Signed-off-by: David Linares <dlinares.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>