xen-blkback: implement safe iterator for the list of persistent grants

Change foreach_grant iterator to a safe version, that allows freeing
the element while iterating. Also move the free code in
free_persistent_gnts to prevent freeing the element before the rb_next
call.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: xen-devel@lists.xen.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
llist/xen-blkfront: implement safe version of llist_for_each_entry

Implement a safe version of llist_for_each_entry, and use it in
blkif_free. Previously grants where freed while iterating the list,
which lead to dereferences when trying to fetch the next item.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by:  Andrew Morton <akpm@linux-foundation.org>
[v2: Move the llist_for_each_entry_safe in llist.h]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
xen-blkfront: handle bvecs with partial data

Currently blkfront fails to handle cases in blkif_completion like the
following:

1st loop in rq_for_each_segment
 * bv_offset: 3584
 * bv_len: 512
 * offset += bv_len
 * i: 0

2nd loop:
 * bv_offset: 0
 * bv_len: 512
 * i: 0

In the second loop i should be 1, since we assume we only wanted to
read a part of the previous page. This patches fixes this cases where
only a part of the shared page is read, and blkif_completion assumes
that if the bv_offset of a bvec is less than the previous bv_offset
plus the bv_size we have to switch to the next shared page.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: linux-kernel@vger.kernel.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
block: remove deadlock in disk_clear_events

In disk_clear_events, do not put work on system_nrt_freezable_wq.
Instead, put it on system_nrt_wq.

There is a race between probing a usb and suspending the device.  Since
probing a usb calls disk_clear_events, which puts work on a frozen
workqueue, probing cannot finish after the workqueue is frozen.  However,
suspending cannot finish until the usb probe is finished, so we get a
deadlock, causing the system to reboot.

The way to reproduce this bug is to wake up from suspend with a usb
storage device plugged in, or plugging in a usb storage device right
before suspend.  The window of time is on the order of time it takes to
probe the usb device.  As long as the workqueues are frozen before the
call to add_disk within sd_probe_async finishes, there will be a deadlock
(which calls blkdev_get, sd_open, check_disk_change, then
disk_clear_events).  This is not difficult to reproduce after figuring out
the timings.

[akpm@linux-foundation.org: fix up comment]
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: prevent race/cleanup

Remove a race condition which causes a warning in disk_clear_events.  This
is a race between disk_clear_events() and disk_flush_events().
ev->clearing will be altered by disk_flush_events() even though we are
blocking event checking through disk_flush_events().  If this happens
after ev->clearing was cleared for disk_clear_events(), this can cause the
WARN_ON_ONCE() in that function to be triggered.

This change also has disk_clear_events() not go through a workqueue.
Since we have to wait for the work to complete, we should just call the
function directly.  Also, since this work cannot be put on a freezable
workqueue, it will have to contend with increased demand, so calling the
function directly avoids this.

[akpm@linux-foundation.org: fix spello in comment]
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge branch 'stable/for-jens-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus

Konrad writes:

Please git pull the following branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/for-jens-3.8

which has a bug-fix to the xen-blkfront and xen-blkback driver
when using the persistent mode. An issue was discovered where LVM
disks could not be read correctly and this fixes it. There
is also a change in llist.h which has been blessed by akpm.
mtip32xx: fix for driver hang after a command timeout

If an I/O command times out when a PIO command is active,
MTIP_PF_EH_ACTIVE_BIT is not cleared. This results in I/O
hang in the driver. Fix is to clear this bit.

Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
mtip32xx: fix for crash when the device surprise removed during rebuild

When rebuild is in progress, disk->queue is yet to be created. Surprise
removing the device will call remove()-> del_gendisk(). del_gendisk()
expect disk->queue be not NULL. Fix is to call put_disk() when disk_queue
is NULL.

Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
drbd: fix potential protocol error and resulting disconnect/reconnect

When we notice a disk failure on the receiving side,
we stop sending it new incoming writes.

Depending on exact timing of various events, the same transfer log epoch
could end up containing both replicated (before we noticed the failure)
and local-only requests (after we noticed the failure).

The sanity checks in tl_release(), called when receiving a
P_BARRIER_ACK, check that the ack'ed transfer log epoch matches
the expected epoch, and the number of contained writes matches
the number of ack'ed writes.

In this case, they counted both replicated and local-only writes,
but the peer only acknowledges those it has seen.  We get a mismatch,
resulting in a protocol error and disconnect/reconnect cycle.

Messages logged are
  "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n"

A similar issue can also be triggered when starting a resync while
having a healthy replication link, by invalidating one side, forcing a
full sync, or attaching to a diskless node.

Fix this by closing the current epoch if the state changes in a way
that would cause the replication intent of the next write.

Epochs now contain either only non-replicated,
or only replicated writes.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Merge branch 'for-jens' of git://git.drbd.org/linux-drbd into for-linus
xhci: Fix isoc TD encoding.

An isochronous TD is comprised of one isochronous TRB chained to zero or
more normal TRBs.  Only the isoc TRB has the TBC and TLBPC fields.  The
normal TRBs must set those fields to zeroes.  The code was setting the
TBC and TLBPC fields for both isoc and normal TRBs.  Fix this.

This should be backported to stable kernels as old as 3.0, that contain
the commit b61d378f2da41c748aba6ca19d77e1e1c02bcea5 " xhci 1.0: Set
transfer burst last packet count field."

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
xhci: Fix TD size for isochronous URBs.

To calculate the TD size for a particular TRB in an isoc TD, we need
know the endpoint's max packet size.  Isochronous endpoints also encode
the number of additional service opportunities in their wMaxPacketSize
field.  The TD size calculation did not mask off those bits before using
the field.  This resulted in incorrect TD size information for
isochronous TRBs when an URB frame buffer crossed a 64KB boundary.

For example:
 - an isoc endpoint has 2 additional service opportunites and
   a max packet size of 1020 bytes
 - a frame transfer buffer contains 3060 bytes
 - one frame buffer crosses a 64KB boundary, and must be split into
   one 1276 byte TRB, and one 1784 byte TRB.

The TD size is is the number of packets that remain to be transferred
for a TD after processing all the max packet sized packets in the
current TRB and all previous TRBs.

For this TD, the number of packets to be transferred is (3060 / 1020),
or 3.  The first TRB contains 1276 bytes, which means it contains one
full packet, and a 256 byte remainder.  After processing all the max
packet-sized packets in the first TRB, the host will have 2 packets left
to transfer.

The old code would calculate the TD size for the first TRB as:

total packet count = DIV_ROUND_UP (TD length / endpoint wMaxPacketSize)
total packet count - (first TRB length / endpoint wMaxPacketSize)

The math should have been:

total packet count = DIV_ROUND_UP (3060 / 1020) = 3
3 - (1276 / 1020) = 2

Since the old code didn't mask off the additional service interval bits
from the wMaxPacketSize field, the math ended up as

total packet count = DIV_ROUND_UP (3060 / 5116) = 1
1 - (1276 / 5116) = 1

Fix this by masking off the number of additional service opportunities
in the wMaxPacketSize field.

This patch should be backported to stable kernels as old as 3.0, that
contain the commit 4da6e6f247a2601ab9f1e63424e4d944ed4124f3 "xhci 1.0:
Update TD size field format."  It may not apply well to kernels older
than 3.2 because of commit 29cc88979a8818cd8c5019426e945aed118b400e
"USB: use usb_endpoint_maxp() instead of le16_to_cpu()".

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
drivers: xhci: fix incorrect bit test

Fix incorrect bit test that originally showed up in
4ee823b83bc9851743fab756c76b27d6a1e2472b "USB/xHCI: Support
device-initiated USB 3.0 resume."

Use '&' instead of '&&'.

This should be backported to kernels as old as 3.4.

Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
USB: XHCI: fix memory leak of URB-private data

This patch (as1640) fixes a memory leak in xhci-hcd.  The urb_priv
data structure isn't always deallocated in the handle_tx_event()
routine for non-control transfers.  The patch adds a kfree() call so
that all paths end up freeing the memory properly.

This patch should be backported to kernels as old as 2.6.36, that
contain the commit 8e51adccd4c4b9ffcd509d7f2afce0a906139f75 "USB: xHCI:
Introduce urb_priv structure"

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Reported-and-tested-by: Martin Mokrejs <mmokrejs@fold.natur.cuni.cz>
CC: <stable@vger.kernel.org>
usb: Prevent dead ports when xhci is not enabled

When the xHCI driver is not available, actively switch the ports to EHCI
mode since some BIOSes leave them in xHCI mode where they would
otherwise appear dead.  This was discovered on a  Dell Optiplex 7010,
but it's possible other systems could be affected.

This should be backported to kernels as old as 3.0, that contain the
commit 69e848c2090aebba5698a1620604c7dccb448684 "Intel xhci: Support
EHCI/xHCI port switching."

Signed-off-by: David Moore <david.moore@gmail.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
usb: Using correct way to clear usb3.0 device's remote wakeup feature.

Usb3.0 device defines function remote wakeup which is only for interface
recipient rather than device recipient. This is different with usb2.0 device's
remote wakeup feature which is defined for device recipient. According usb3.0
spec 9.4.5, the function remote wakeup can be modified by the SetFeature()
requests using the FUNCTION_SUSPEND feature selector. This patch is to use
correct way to disable usb3.0 device's function remote wakeup after suspend
error and resuming.

This should be backported to kernels as old as 3.4, that contain the
commit 623bef9e03a60adc623b09673297ca7a1cdfb367 "USB/xhci: Enable remote
wakeup for USB3 devices."

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
[media] radio: set vfl_dir correctly to fix modulator regression

The vfl_dir field should be set to indicate whether a device can receive
data, output data or can do both. This is used to let the v4l core know
which ioctls should be accepted and which can be refused.
Unfortunately, when this field was added the radio modulator drivers were
not updated: radio modulators transmit and so vfl_dir should be set to
VFL_DIR_TX (or VFL_DIR_M2M in the special case of wl128x).
Because of this omission it is not possible to call g/s_modulator for these
drivers, which effectively renders them useless.
This patch sets the correct vfl_dir value for these drivers, correcting
this bug.
Thanks to Paul Grinberg for bringing this to my attention.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Merge tag 'for-usb-linus-2012-01-24' of git://git.kernel.org/pub/scm/linux/kernel/git/sarah/xhci into usb-linus

Sarah writes:
	USB/xhci: Misc fixes for 3.8.

	Hi Greg,

	Here's six patches for xHCI and the USB core.  There's a couple of
	patches to fix xHCI 1.0 field formats, some memory leaks, dead ports,
	and USB 3.0 remote wakeup disabling.

	All of these are marked for stable.

	I know I owe you some re-works of failed stable patches from my last
	patchset round, but I don't think I'm going to get to them before I head
	off to Linux Conf Australia tomorrow.

	Sarah Sharp
USB: EHCI: remove ASS/PSS polling timeout

This patch (as1647) attempts to work around a problem that seems to
affect some nVidia EHCI controllers.  They sometimes take a very long
time to turn off their async or periodic schedules.  I don't know if
this is a result of other problems, but in any case it seems wise not
to depend on schedule enables or disables taking effect in any
specific length of time.

The patch removes the existing 20-ms timeout for enabling and
disabling the schedules.  The driver will now continue to poll the
schedule state at 1-ms intervals until the controller finally decides
to obey the most recent command issued by the driver.  Just in case
this hides a problem, a debugging message will be logged if the
controller takes longer than 20 polls.

I don't know if this will actually fix anything, but it can't hurt.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
USB: EHCI: unlink one async QH at a time

This patch (as1648) fixes a regression affecting nVidia EHCI
controllers.  Evidently they don't like to have more than one async QH
unlinked at a time.  I can't imagine how they manage to mess it up,
but at least one of them does.

The patch changes the async unlink logic in two ways:

	Each time an IAA cycle is started, only the first QH on the
	async unlink list is handled (rather than all of them).

	Async QHs do not all get unlinked as soon as they have been
	empty for long enough.  Instead, only the last one (i.e., the
	one that has been on the schedule the longest) is unlinked,
	and then only if no other unlinks are in progress at the time.

This means that when multiple QHs are empty, they won't be unlinked as
quickly as before.  That's okay; it won't affect correct operation of
the driver or add an excessive load.  Multiple unlinks tend to be
relatively rare in any case.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>
Cc: stable <stable@vger.kernel.org> # 3.6
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>