just what it sounds like; do that only to procfs subtrees you've
created - doing that to something shared with another driver is
not only antisocial, but might cause interesting races with
proc_create() and its ilk.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Pull vfs fixes from Al Viro:
 "stable fodder; assorted deadlock fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  vt: synchronize_rcu() under spinlock is not nice...
  Nest rename_lock inside vfsmount_lock
  Don't bother with redoing rw_verify_area() from default_file_splice_from()

vcs_poll_data_free() calls unregister_vt_notifier(), which calls
atomic_notifier_chain_unregister(), which calls synchronize_rcu().
Do it *after* we'd dropped ->f_lock.

Cc: stable@vger.kernel.org (all kernels since 2.6.37)
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... lest we get livelocks between path_is_under() and d_path() and friends.

The thing is, wrt fairness lglocks are more similar to rwsems than to rwlocks;
it is possible to have thread B spin on attempt to take lock shared while thread
A is already holding it shared, if B is on lower-numbered CPU than A and there's
a thread C spinning on attempt to take the same lock exclusive.

As the result, we need consistent ordering between vfsmount_lock (lglock) and
rename_lock (seq_lock), even though everything that takes both is going to take
vfsmount_lock only shared.
Spotted-by: NBrad Spengler <spender@grsecurity.net>
Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Pull networking fixes from David Miller:

 1) Always increment IPV4 ID field in encapsulated GSO packets, even
    when DF is set.  Regression fix from Pravin B Shelar.

 2) Fix per-net subsystem initialization in netfilter conntrack,
    otherwise we may access dynamically allocated memory before it is
    actually allocated.  From Gao Feng.

 3) Fix DMA buffer lengths in iwl3945 driver, from Stanislaw Gruszka.

 4) Fix race between submission of sync vs async commands in mwifiex
    driver, from Amitkumar Karwar.

 5) Add missing cancel of command timer in mwifiex driver, from Bing
    Zhao.

 6) Missing SKB free in rtlwifi USB driver, from Jussi Kivilinna.

 7) Thermal layer tries to use a genetlink multicast string that is
    longer than the 16 character limit.  Fix it and add a BUG check to
    prevent this kind of thing from happening in the future.

 From Masatake YAMATO.

 8) Fix many bugs in the handling of the teardown of L2TP connections,
    UDP encapsulation instances, and sockets.  From Tom Parkin.

 9) Missing socket release in IRDA, from Kees Cook.

10) Fix fec driver modular build, from Fabio Estevam.

11) Erroneous use of kfree() instead of free_netdev() in lantiq_etop,
    from Wei Yongjun.

12) Fix bugs in handling of queue numbers and steering rules in mlx4
    driver, from Moshe Lazer, Hadar Hen Zion, and Or Gerlitz.

13) Some FOO_DIAG_MAX constants were defined off by one, fix from Andrey
    Vagin.

14) TCP segmentation deferral is unintentionally done too strongly,
    breaking ACK clocking.  Fix from Eric Dumazet.

15) net_enable_timestamp() can legitimately be invoked from software
    interrupts, and in a way that is safe, so remove the WARN_ON().
    Also from Eric Dumazet.

16) Fix use after free in VLANs, from Cong Wang.

17) Fix TCP slow start retransmit storms after SACK reneging, from
    Yuchung Cheng.

18) Unix socket release should mark a socket dead before NULL'ing out
    sock->sk, otherwise we can race.  Fix from Paul Moore.

19) IPV6 addrconf code can try to free static memory, from Hong Zhiguo.

20) Fix register mis-programming, NULL pointer derefs, and wrong PHC
    clock frequency in IGB driver.  From Lior LevyAlex Williamson, Jiri
    Benc, and Jeff Kirsher.

21) skb->ip_summed logic in pch_gbe driver is reversed, breaking packet
    forwarding.  Fix from Veaceslav Falico.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (65 commits)
  ipv4: Fix ip-header identification for gso packets.
  bonding: remove already created master sysfs link on failure
  af_unix: dont send SCM_CREDENTIAL when dest socket is NULL
  pch_gbe: fix ip_summed checksum reporting on rx
  igb: fix PHC stopping on max freq
  igb: make sensor info static
  igb: SR-IOV init reordering
  igb: Fix null pointer dereference
  igb: fix i350 anti spoofing config
  ixgbevf: don't release the soft entries
  ipv6: fix bad free of addrconf_init_net
  unix: fix a race condition in unix_release()
  tcp: undo spurious timeout after SACK reneging
  bnx2x: fix assignment of signed expression to unsigned variable
  bridge: fix crash when set mac address of br interface
  8021q: fix a potential use-after-free
  net: remove a WARN_ON() in net_enable_timestamp()
  tcp: preserve ACK clocking in TSO
  net: fix *_DIAG_MAX constants
  net/mlx4_core: Disallow releasing VF QPs which have steering rules
  ...

Pull NFS client bugfixes from Trond Myklebust:
 - Fix an NFSv4 idmapper regression
 - Fix an Oops in the pNFS blocks client
 - Fix up various issues with pNFS layoutcommit
 - Ensure correct read ordering of variables in
   rpc_wake_up_task_queue_locked

* tag 'nfs-for-3.9-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  SUNRPC: Add barriers to ensure read ordering in rpc_wake_up_task_queue_locked
  NFSv4.1: Add a helper pnfs_commit_and_return_layout
  NFSv4.1: Always clear the NFS_INO_LAYOUTCOMMIT in layoutreturn
  NFSv4.1: Fix a race in pNFS layoutcommit
  pnfs-block: removing DM device maybe cause oops when call dev_remove
  NFSv4: Fix the string length returned by the idmapper

ip-header id needs to be incremented even if IP_DF flag is set.
This behaviour was changed in commit 490ab081
(IP_GRE: Fix IP-Identification).

Following patch fixes it so that identification is always
incremented.
Reported-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If slave sysfs symlink failes to be created - we end up without removing
the master sysfs symlink. Remove it in case of failure.
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SCM_SCREDENTIALS should apply to write() syscalls only either source or destination
socket asserted SOCK_PASSCRED. The original implememtation in maybe_add_creds is wrong,
and breaks several LSB testcases ( i.e. /tset/LSB.os/netowkr/recvfrom/T.recvfrom).
Origionally-authored-by: NKarel Srot <ksrot@redhat.com>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jeff Kirsher says:

====================
This series contains updates to ixgbevf and igb.

The ixgbevf calls to pci_disable_msix() and to free the msix_entries
memory should not occur if device open fails.  Instead they should be
called during device driver removal to balance with the call to
pci_enable_msix() and the call to allocate msix_entries memory
during the device probe and driver load.

The remaining 4 of 5 igb patches are simple 1-3 line patches to fix
several issues such as possible null pointer dereference, PHC stopping
on max frequency, make sensor info static and SR-IOV initialization
reordering.

The remaining igb patch to fix anti-spoofing config fixes a problem
in i350 where anti spoofing configuration was written into a wrong
register.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

skb->ip_summed should be CHECKSUM_UNNECESSARY when the driver reports that
checksums were correct and CHECKSUM_NONE in any other case. They're
currently placed vice versa, which breaks the forwarding scenario. Fix it
by placing them as described above.
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For 82576 MAC type, max_adj is reported as 1000000000 ppb. However, if
this value is passed to igb_ptp_adjfreq_82576, incvalue overflows out of
INCVALUE_82576_MASK, resulting in setting of zero TIMINCA.incvalue, stopping
the PHC (instead of going at twice the nominal speed).

Fix the advertised max_adj value to the largest value hardware can handle.
As there is no min_adj value available (-max_adj is used instead), this will
also prevent stopping the clock intentionally. It's probably not a big deal,
other igb MAC types don't support stopping the clock, either.
Signed-off-by: NJiri Benc <jbenc@redhat.com>
Acked-by: NMatthew Vick <matthew.vick@intel.com>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Trivial sparse warning.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

igb is ineffective at setting a lower total VFs because:

int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
{
        ...
        /* Shouldn't change if VFs already enabled */
        if (dev->sriov->ctrl & PCI_SRIOV_CTRL_VFE)
                return -EBUSY;

Swap init ordering.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NGreg Rose <gregory.v.rose@intel.com>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

The max_vfs= option has always been self limiting to the number of VFs
supported by the device.  fa44f2f1 added SR-IOV configuration via
sysfs, but in the process broke this self correction factor.  The
failing path is:

igb_probe
  igb_sw_init
    if (max_vfs > 7) {
        adapter->vfs_allocated_count = 7;
    ...
    igb_probe_vfs
    igb_enable_sriov(, max_vfs)
      if (num_vfs > 7) {
        err = -EPERM;
        ...

This leaves vfs_allocated_count = 7 and vf_data = NULL, so we bomb out
when igb_probe finally calls igb_reset.  It seems like a really bad
idea, and somewhat pointless, to set vfs_allocated_count separate from
vf_data, but limiting max_vfs is enough to avoid the null pointer.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NGreg Rose <gregory.v.rose@intel.com>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Fix a problem in i350 where anti spoofing configuration was written into a
wrong register.
Signed-off-by: NLior Levy <lior.levy@intel.com>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

When the ixgbevf driver is opened the request to allocate MSIX irq
vectors may fail.  In that case the driver will call ixgbevf_down()
which will call ixgbevf_irq_disable() to clear the HW interrupt
registers and calls synchronize_irq() using the msix_entries pointer in
the adapter structure.  However, when the function to request the MSIX
irq vectors failed it had already freed the msix_entries which causes
an OOPs from using the NULL pointer in synchronize_irq().

The calls to pci_disable_msix() and to free the msix_entries memory
should not occur if device open fails.  Instead they should be called
during device driver removal to balance with the call to
pci_enable_msix() and the call to allocate msix_entries memory
during the device probe and driver load.
Signed-off-by: NLi Xun <xunleer.li@huawei.com>
Signed-off-by: NGreg Rose <gregory.v.rose@intel.com>
Tested-by: NSibai Li <sibai.li@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Pull timer fix from Thomas Gleixner:
 "A single bugfix which prevents that a non functional timer device is
  selected to provide the fallback device, which is supposed to serve
  timer interrupts on behalf of non functional devices ..."

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clockevents: Don't allow dummy broadcast timers

Signed-off-by: NHong Zhiguo <honkiko@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As reported by Jan, and others over the past few years, there is a
race condition caused by unix_release setting the sock->sk pointer
to NULL before properly marking the socket as dead/orphaned.  This
can cause a problem with the LSM hook security_unix_may_send() if
there is another socket attempting to write to this partially
released socket in between when sock->sk is set to NULL and it is
marked as dead/orphaned.  This patch fixes this by only setting
sock->sk to NULL after the socket has been marked as dead; I also
take the opportunity to make unix_release_sock() a void function
as it only ever returned 0/success.

Dave, I think this one should go on the -stable pile.

Special thanks to Jan for coming up with a reproducer for this
problem.
Reported-by: NJan Stancek <jan.stancek@gmail.com>
Signed-off-by: NPaul Moore <pmoore@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pull infiniband/rdma fixes from Roland Dreier:
 "Small batch of InfiniBand/RDMA fixes for 3.9:

   - Fix for TX lockup in IPoIB
   - QLogic -> Intel update for qib driver
   - Small static checker fix for qib
   - Fix error path return value in cxgb4"

* tag 'rdma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  IB/qib: change QLogic to Intel
  IB/ipath: Silence a static checker warning
  IPoIB: Fix send lockup due to missed TX completion
  RDMA/cxgb4: Fix error return code in create_qp()

Pull ARM SoC bug fixes from Arnd Bergmann:
 "Four patches for arm-soc this week:

   - Kevin Hilman is no longer reachable under his previous email
     address.  He submitted the patch earlier, but nobody felt
     responsible to pick it up.

   - One Tegra fix for an incorect register address in device tree.

   - IMX multiplatform support exposes a configuration option that leads
     to unbootable kernels on all other machines and that needs to
     depend on that platform.

   - A nontrivial bug fix for the setup of the mxs video output."

* tag 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  MAINTAINERS: update email address for Kevin Hilman
  ARM: tegra: fix register address of slink controller
  ARM: imx: add dependency check for DEBUG_IMX_UART_PORT
  ARM: video: mxs: Fix mxsfb misconfiguring VDCTRL0

Pull nfsd bugfixes from J Bruce Fields:
 "Fixes for a couple mistakes in the new DRC code.  And thanks to Kent
  Overstreet for noticing we've been sync'ing the wrong range on stable
  writes since 3.8."

* 'for-3.9' of git://linux-nfs.org/~bfields/linux:
  nfsd: fix bad offset use
  nfsd: fix startup order in nfsd_reply_cache_init
  nfsd: only unhash DRC entries that are in the hashtable

We need to be careful when testing task->tk_waitqueue in
rpc_wake_up_task_queue_locked, because it can be changed while we
are holding the queue->lock.
By adding appropriate memory barriers, we can ensure that it is safe to
test task->tk_waitqueue for equality if the RPC_TASK_QUEUED bit is set.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

Pull drm fixes from Dave Airlie:
 "Exynos and Intel fixes.

  The intel fixes are fairly straightforward, mostly reverts due to bugs
  found.  The exynos one is a big larger since they found some issues
  with the G2D engine and iommu interaction, and needed to verify the
  operations a lot better than they were previously, otherwise a user
  app can just crash the kernel with an iommu fault."

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  Revert "drm/i915: write backlight harder"
  drm/i915: don't disable the power well yet
  Revert "drm/i915: set TRANSCODER_EDP even earlier"
  drm/exynos: Check g2d cmd list for g2d restrictions
  drm/exynos: Add a new function to get gem buffer size
  drm/exynos: Deal with g2d buffer info more efficiently
  drm/exynos: Clean up some G2D codes for readability
  drm/exynos: Fix G2D core malfunctioning issue
  drm/exynos: clear node object type at gem unmap
  drm/exynos: Fix error routine to getting dma addr.
  drm/exynos: Replaced kzalloc & memcpy with kmemdup
  drm/exynos: fimd: calculate the correct address offset
  drm/exynos: Make mixer_check_timing static
  drm/exynos: modify the compatible string for exynos fimd

Daniel writes:
"Just three revert/disable by default patches, one of them cc: stable
(since the offending commit was cc: stable, too)."

* 'drm-intel-fixes' of git://people.freedesktop.org/~danvet/drm-intel:
  Revert "drm/i915: write backlight harder"
  drm/i915: don't disable the power well yet
  Revert "drm/i915: set TRANSCODER_EDP even earlier"

Merge branch 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos into HEAD

Inki writes:
Includes bug fixes and code cleanups.
And it considers some restrictions to G2D hardware.
With this, the malfunction and page fault issues to g2d driver
would be fixed.

* 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos:
  drm/exynos: Check g2d cmd list for g2d restrictions
  drm/exynos: Add a new function to get gem buffer size
  drm/exynos: Deal with g2d buffer info more efficiently
  drm/exynos: Clean up some G2D codes for readability
  drm/exynos: Fix G2D core malfunctioning issue
  drm/exynos: clear node object type at gem unmap
  drm/exynos: Fix error routine to getting dma addr.
  drm/exynos: Replaced kzalloc & memcpy with kmemdup
  drm/exynos: fimd: calculate the correct address offset
  drm/exynos: Make mixer_check_timing static
  drm/exynos: modify the compatible string for exynos fimd

On SACK reneging the sender immediately retransmits and forces a
timeout but disables Eifel (undo). If the (buggy) receiver does not
drop any packet this can trigger a false slow-start retransmit storm
driven by the ACKs of the original packets. This can be detected with
undo and TCP timestamps.
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

fix for incorrect assignment of signed expression to unsigned variable.
Signed-off-by: NKumar Amit Mehta <gmate.amit@gmail.com>
Acked-by: NDmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When I tried to set mac address of a bridge interface to a mac
address which already learned on this bridge, I got system hang.

The cause is straight forward: function br_fdb_change_mac_address
calls fdb_insert with NULL source nbp. Then an fdb lookup is
performed. If an fdb entry is found and it's local, it's OK. But
if it's not local, source is dereferenced for printk without NULL
check.
Signed-off-by: NHong Zhiguo <honkiko@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

vlan_vid_del() could possibly free ->vlan_info after a RCU grace
period, however, we may still refer to the freed memory area
by 'grp' pointer. Found by code inspection.

This patch moves vlan_vid_del() as behind as possible.

Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NCong Wang <amwang@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The WARN_ON(in_interrupt()) in net_enable_timestamp() can get false
positive, in socket clone path, run from softirq context :

[ 3641.624425] WARNING: at net/core/dev.c:1532 net_enable_timestamp+0x7b/0x80()
[ 3641.668811] Call Trace:
[ 3641.671254]  <IRQ>  [<ffffffff80286817>] warn_slowpath_common+0x87/0xc0
[ 3641.677871]  [<ffffffff8028686a>] warn_slowpath_null+0x1a/0x20
[ 3641.683683]  [<ffffffff80742f8b>] net_enable_timestamp+0x7b/0x80
[ 3641.689668]  [<ffffffff80732ce5>] sk_clone_lock+0x425/0x450
[ 3641.695222]  [<ffffffff8078db36>] inet_csk_clone_lock+0x16/0x170
[ 3641.701213]  [<ffffffff807ae449>] tcp_create_openreq_child+0x29/0x820
[ 3641.707663]  [<ffffffff807d62e2>] ? ipt_do_table+0x222/0x670
[ 3641.713354]  [<ffffffff807aaf5b>] tcp_v4_syn_recv_sock+0xab/0x3d0
[ 3641.719425]  [<ffffffff807af63a>] tcp_check_req+0x3da/0x530
[ 3641.724979]  [<ffffffff8078b400>] ? inet_hashinfo_init+0x60/0x80
[ 3641.730964]  [<ffffffff807ade6f>] ? tcp_v4_rcv+0x79f/0xbe0
[ 3641.736430]  [<ffffffff807ab9bd>] tcp_v4_do_rcv+0x38d/0x4f0
[ 3641.741985]  [<ffffffff807ae14a>] tcp_v4_rcv+0xa7a/0xbe0

Its safe at this point because the parent socket owns a reference
on the netstamp_needed, so we cant have a 0 -> 1 transition, which
requires to lock a mutex.

Instead of refining the check, lets remove it, as all known callers
are safe. If it ever changes in the future, static_key_slow_inc()
will complain anyway.
Reported-by: NLaurent Chavey <chavey@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Merge tag 'pinctrl-fixes-for-v3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl

Pull pinctrl fixes from Linus Walleij:
 "Here are a few pinctrl fixes for the v3.9 rc series:
   - Usecount bounds checking so we do not go below zero on mux
     usecounts.
   - Loop range checking in GPIO ranges in the DT range parser.
   - Proper print in debugfs for pinconf state.
   - Fix compilation bug in generic pinconf code.
   - Minor bugfixes to abx500 and mvebu drivers."

* tag 'pinctrl-fixes-for-v3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinmux: forbid mux_usecount to be set at UINT_MAX
  pinctrl: mvebu: fix checking for SoC specific controls
  pinctrl: generic: Fix compilation error
  pinctrl: Print the correct information in debugfs pinconf-state file
  pinctrl: abx500: Fix checking if pin use AlternateFunction register
  gpio: fix wrong checking condition for gpio range

Pull x86 fixes from Peter Anvin:
 "A collection of minor fixes, more EFI variables paranoia
  (anti-bricking) plus the ability to disable the pstore either as a
  runtime default or completely, due to bricking concerns."

* 'x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efivars: Fix check for CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE
  x86, microcode_intel_early: Mark apply_microcode_early() as cpuinit
  efivars: Handle duplicate names from get_next_variable()
  efivars: explicitly calculate length of VariableName
  efivars: Add module parameter to disable use as a pstore backend
  efivars: Allow disabling use as a pstore backend
  x86-32, microcode_intel_early: Fix crash with CONFIG_DEBUG_VIRTUAL
  x86-64: Fix the failure case in copy_user_handle_tail()

This reverts commit cf0a6584.

Turns out that cargo-culting breaks systems. Note that we can't revert
further, since

commit 770c1231
Author: Takashi Iwai <tiwai@suse.de>
Date:   Sat Aug 11 08:56:42 2012 +0200

    drm/i915: Fix blank panel at reopening lid

fixed a regression in 3.6-rc kernels for which we've never figured out
the exact root cause. But some further inspection of the backlight
code reveals that it's seriously lacking locking. And especially the
asle backlight update is know to get fired (through some smm magic)
when writing specific backlight control registers. So the possibility
of suffering from races is rather real.

Until those races are fixed I don't think it makes sense to try
further hacks. Which sucks a bit, but sometimes that's how it is :(

References: http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg18788.html
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47941Tested-by: NTakashi Iwai <tiwai@suse.de>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: stable@vger.kernel.org (the reverted commit was cc: stable, too)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We're still not 100% ready to disable the power well, so don't disable
it for now. When we disable it we break the audio driver (because some
of the audio registers are on the power well) and machines with eDP on
port D (because it doesn't use TRANSCODER_EDP).

Also, instead of just reverting the code, add a Kernel option to let
us disable it if we want. This will allow us to keep developing and
testing the feature while it's not enabled.

This fixes problems caused by the following commit:
  commit d6dd9eb1
  Author: Daniel Vetter <daniel.vetter@ffwll.ch>
  Date:   Tue Jan 29 16:35:20 2013 -0200
       drm/i915: dynamic Haswell display power well support

References: http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg18788.html
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This reverts commit cc464b2a.

The reason is that Takashi Iwai reported a regression bisected to this
commit:

http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg18788.html

His machine has eDP on port D (usual desktop all-in-on setup), which
intel_dp.c identifies as an eDP panel, but the hsw ddi code
mishandles.

Closer inspection of the code reveals that haswell_crtc_mode_set also
checks intel_encoder_is_pch_edp when setting is_cpu_edp. On haswell
that doesn't make much sense (since there's no edp on the pch), but
what this function _really_ checks is whether that edp connector is on
port A or port D. It's just that on ilk-ivb port D was on the pch ...

So that explains why this seemingly innocent change killed eDP on port
D. Furthermore it looks like everything else accidentally works, since
we've never enabled eDP on port D support for hsw intentionally (e.g.
we still register the HDMI output for port D in that case).

But in retrospective I also don't like that this leaks highly platform
specific details into common code, and the reason is that the drm
vblank layer sucks. So instead I think we should:
- move the cpu_transcoder into the dynamic pipe_config tracking (once
  that's merged).
- fix up the drm vblank layer to finally deal with kms crtc objects
  instead of int pipes.

v2: Pimp commit message with the better diagnosis as discussed with
Paulo on irc.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>