kernel.git/drivers/usb/core/urb.c, branch linux-3.13.y

usb-anchor: Delay usb_wait_anchor_empty_timeout wake up till completion is done

2013-10-11T23:33:58Z

usb_wait_anchor_empty_timeout() should wait till the completion handler has run. Both the zd1211rw driver and the uas driver (in its task mgmt) depend on the completion handler having completed when usb_wait_anchor_empty_timeout() returns, as they read state set by the completion handler after an usb_wait_anchor_empty_timeout() call. But __usb_hcd_giveback_urb() calls usb_unanchor_urb before calling the completion handler. This is necessary as the completion handler may re-submit and re-anchor the urb. But this introduces a race where the state these drivers want to read has not been set yet by the completion handler (this race is easily triggered with the uas task mgmt code). I've considered adding an anchor_count to struct urb, which would be incremented on anchor and decremented on unanchor, and then only actually do the anchor / unanchor on 0 -> 1 and 1 -> 0 transtions, combined with moving the unanchor call in hcd_giveback_urb to after calling the completion handler. But this will only work if urb's are only re-anchored to the same anchor as they were anchored to before the completion handler ran. And at least one driver re-anchors to another anchor from the completion handler (rtlwifi). So I have come up with this patch instead, which adds the ability to suspend wakeups of usb_wait_anchor_empty_timeout() waiters to the usb_anchor functionality, and uses this in __usb_hcd_giveback_urb() to delay wake-ups until the completion handler has run. Signed-off-by: Hans de Goede Acked-by: Oliver Neukum Signed-off-by: Greg Kroah-Hartman

USB: introduce usb_device_no_sg_constraint() helper

2013-08-12T18:56:16Z

Some host controllers(such as xHCI) can support building packet from discontinuous buffers, so introduce one flag and helper for this kind of host controllers, then the feature can help some applications(such as usbnet) by supporting arbitrary length of sg buffers. Acked-by: Alan Stern Signed-off-by: Ming Lei Reviewed-by: Eric Dumazet Signed-off-by: Greg Kroah-Hartman

usb: fix some scripts/kernel-doc warnings

2013-08-03T03:30:14Z

When building the htmldocs (in verbose mode), scripts/kernel-doc reports the following type of warnings: Warning(drivers/usb/core/usb.c:76): No description found for return value of 'usb_find_alt_setting' Fix them by: - adding some missing descriptions of return values - using "Return" sections for those descriptions Signed-off-by: Yacine Belkadi Signed-off-by: Greg Kroah-Hartman

USB: check sg buffer size in usb_submit_urb

2013-07-24T22:52:43Z

USB spec stats that short packet can only appear at the end of transfer. Because lost of HC(EHCI/UHCI/OHCI/...) can't build a full packet from discontinuous buffers, we introduce the limit in usb_submit_urb() to avoid such kind of bad sg buffers coming from driver. The limit might be a bit strict: - platform has iommu to do sg list mapping - some host controllers may support to build full packet from discontinuous buffers. But considered that most of HCs don't support that, and driver need work well or keep consistent on different HCs and ARCHs, we have to introduce the limit. Currently, only usbtest is reported to pass such sg buffers to HC, and other users(mass storage, usbfs) don't have the problem. We don't check it on USB wireless device, because: - wireless devices can't be attached to common USB bus(EHCI/UHCI/OHCI/...) - the max packet size of endpoint may be odd, and often can't devide 4KB which is a typical usage in usb mass storage application Reported-by: Konstantin Filatov Reported-by: Denis V. Lunev Cc: Felipe Balbi Acked-by: Alan Stern Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman

USB: fix urb-poison imbalance

2013-03-25T20:48:27Z

The calls to usb_poison_urb and usb_unpoison_urb are expected to be balanced. However, if an urb that has not yet been submitted is poisoned, its reject counter will not be increased as its ep-field is NULL. A consecutive call to unpoison will thus in fact poison the urb as its reject counter will be decremented to a negative value, effectively preventing the urb from being submitted. Note that there are currently no in-kernel drivers affected by this. Cc: Alan Stern Acked-by: Alan Stern Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: report submission of active URBs

2012-11-12T02:10:46Z

This patch (as1633) changes slightly the way usbcore handled submissions of URBs that are already active. It will now return -EBUSY rather than -EINVAL, and it will call WARN_ONCE to draw people's attention to the bug. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman

USB: update documentation for URB_ISO_ASAP

2012-10-22T18:10:24Z

This patch (as1611) updates the USB documentation and kerneldoc to give a more precise meaning for the URB_ISO_ASAP flag and to explain more of the details of scheduling for isochronous URBs. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman

usbhid: prevent deadlock during timeout

2012-05-01T17:22:13Z

On some HCDs usb_unlink_urb() can directly call the completion handler. That limits the spinlocks that can be taken in the handler to locks not held while calling usb_unlink_urb() To prevent a race with resubmission, this patch exposes usbcore's infrastructure for blocking submission, uses it and so drops the lock without causing a race in usbhid. Signed-off-by: Oliver Neukum Acked-by: Jiri Kosina Cc: stable Signed-off-by: Greg Kroah-Hartman

USB documentation: explain lifetime rules for unlinking URBs

2012-04-06T20:54:00Z

This patch (as1534c) updates the documentation for usb_unlink_urb and related functions. It explains that the caller must prevent the URB being unlinked from getting deallocated while the unlink is taking place. Signed-off-by: Alan Stern CC: Ming Lei Signed-off-by: Greg Kroah-Hartman

usb/core: remove "always" from usb_unlink_urb() kernel doc entry

2012-03-03T00:22:11Z

The kernel doc entry for usb_unlink_urb() contains the phrase "This request is always asynchronous.". The "always" leads to the assumption that the ->complete() callback is not called from within usb_unlink_urb(). This is not true. The HCD is allowed to call the ->complete() from within ->urb_dequeue() if it is appropriate for the hardware. This patch updates the kernel doc so usb-device driver authors make sure to drop all locks (and make sure it is okay to drop them) which are acquired by the complete callback before calling usb_unlink_urb(). Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Greg Kroah-Hartman