If we're looking for a metadata item in the tree and the
search fails with return value of 1, and the slot doesn't
point to the first item in the leaf, check if the previous
item in the leaf corresponds to an extent item for the same
object id - if it does, then don't do another tree search
to get it.

This optimization is already done by btrfs-progs.

V2: updated commit message.
Signed-off-by: NFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Device scanning waits on the uuid_mutex, which can result in a very long
wait if dev delete is shrinking the device.
Signed-off-by: NCarey Underwood <cwillu@cwillu.com>
Reviewed-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

We've been seeing spurious complaints out of lockdep because the lock class name
changes.  This is happening because when we drop a snapshot we will lock a block
before we've read it in, which sets the lockdep class to whatever the default
is.  Then once we read the thing in we reset the lockdep class to what it is
supposed to be, which blows lockdeps' mind.  This patch should fix the problem,
it appears to be the only place where we do this sort of thing.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

With this fix the lzo code behaves like the zlib code by returning an
error
code when compression does not help reduce the size of the file.
This is currently not a bug since the compressed size is checked again
in
the calling method compress_file_range.
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Previously we held the tree mod lock when adding stuff because we use it to
check and see if we truly do want to track tree modifications.  This is
admirable, but GFP_ATOMIC in a critical area that is going to get hit pretty
hard and often is not nice.  So instead do our basic checks to see if we don't
need to track modifications, and if those pass then do our allocation, and then
when we go to insert the new modification check if we still care, and if we
don't just free up our mod and return.  Otherwise we're good to go and we can
carry on.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Pull staging fixes from Greg KH:
 "Here are two tiny staging tree fixes (well, one is for an iio driver,
  but those updates come through the staging tree due to dependancies)

  One fixes a problem with an IIO driver, and the other fixes a bug in
  the comedi driver core"

* tag 'staging-3.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: comedi: bug-fix NULL pointer dereference on failed attach
  iio: adjd_s311: Fix non-scan mode data read

Pull USB fixes from Greg KH:
 "Here are two USB fixes for 3.11-rc7

  One fixes a reported regression in the OHCI driver, and the other
  fixes a reported build breakage in the USB phy drivers"

* tag 'usb-3.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: phy: fix build breakage
  USB: OHCI: add missing PCI PM callbacks to ohci-pci.c

Pull ARM fixes from Russell King:
 "This round of fixes is smaller than previous: a couple more updates
  for the security fixes, and a one-liner kexec fix"

* 'fixes' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: 7816/1: CONFIG_KUSER_HELPERS: fix help text
  ARM: 7815/1: kexec: offline non panic CPUs on Kdump panic
  ARM: 7819/1: fiq: Cast the first argument of flush_icache_range()

Pull vfs fixes from Al Viro:
 "Assorted fixes from the last week or so"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  VFS: collect_mounts() should return an ERR_PTR
  bfs: iget_locked() doesn't return an ERR_PTR
  efs: iget_locked() doesn't return an ERR_PTR()
  proc: kill the extra proc_readfd_common()->dir_emit_dots()
  cope with potentially long ->d_dname() output for shmem/hugetlb

Pull ACPI fix from Rafael Wysocki:
 "I really hoped that it wouldn't be necessary to change anything in
  ACPI at this point, but it turns out that we need to revert one more
  ACPI video commit causing trouble.

  This reverts a change in the ACPI video driver that caused the ACPI
  backlight initialization to be carried out even if acpi_backlight=vendor
  is passed in the kernel command line which turns out to break things
  at least on one system"

* tag 'acpi-3.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "ACPI / video: Always call acpi_video_init_brightness() on init"

Pull SCSI fixes from James Bottomley:
 "This is a set of small bug fixes for lpfc and zfcp and a fix for a
  fairly nasty bug in sg where a process which cancels I/O completes in
  a kernel thread which would then try to write back to the now gone
  userspace and end up writing to a random kernel address instead"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  [SCSI] zfcp: remove access control tables interface (keep sysfs files)
  [SCSI] zfcp: fix schedule-inside-lock in scsi_device list loops
  [SCSI] zfcp: fix lock imbalance by reworking request queue locking
  [SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
  [SCSI] lpfc: Don't force CONFIG_GENERIC_CSUM on

For a search buffer, 2 byte aligned, strchr() was returning pointer
outside of buffer (buf - 1)

------------->8----------------
    // Input buffer (default 4 byte aigned)
    char *buffer = "1AA_";

    // actual search start (to mimick 2 byte alignment)
    char *current_line = &(buffer[2]);

    // Character to search for
    char c = 'A';

    char *c_pos = strchr(current_line, c);

    printf("%s\n", c_pos) --> 'AA_' as oppose to 'A_'
------------->8----------------
Reported-by: NAnton Kolesov <Anton.Kolesov@synopsys.com>
Debugged-by: NAnton Kolesov <Anton.Kolesov@synopsys.com>
Cc: <stable@vger.kernel.org> # [3.9 and 3.10]
Cc: Noam Camus <noamc@ezchip.com>
Signed-off-by: NJoern Rennecke  <joern.rennecke@embecosm.com>
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This should actually be returning an ERR_PTR on error instead of NULL.
That was how it was designed and all the callers expect it.

[AV: actually, that's what "VFS: Make clone_mnt()/copy_tree()/collect_mounts()
return errors" missed - originally collect_mounts() was expected to return
NULL on failure]

Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

iget_locked() returns a NULL on error, it doesn't return an ERR_PTR.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The iget_locked() function returns NULL on error and never an ERR_PTR.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

proc_readfd_common() does dir_emit_dots() twice in a row,
we need to do this only once.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

dynamic_dname() is both too much and too little for those - the
output may be well in excess of 64 bytes dynamic_dname() assumes
to be enough (thanks to ashmem feeding really long names to
shmem_file_setup()) and vsnprintf() is an overkill for those
guys.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Pull libata fixes from Tejun Heo:
 "This contains three commits all of which are updates for specific
  devices which aren't too widespread.  Pretty limited scope and nothing
  too interesting or dangerous"

* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  sata_fsl: save irqs while coalescing
  libata: apply behavioral quirks to sil3826 PMP
  sata, highbank: fix ordering of SGPIO signals

Pull cgroup fix from Tejun Heo:
 "A late fix for cgroup.

  This fixes a behavior regression visible to userland which was created
  by a commit merged during -rc1.  While the behavior change isn't too
  likely to be noticeable, the fix is relatively low risk and we'll need
  to backport it through -stable anyway if the bug gets released"

* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: fix a regression in validating config change

Pull drm fixes from Dave Airlie:
 "Ben was on holidays for a week so a few nouveau regression fixes
  backed up, but they all seem necessary.

  Otherwise one i915 and one gma500 fix"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  gma500: Fix SDVO turning off randomly
  drm/nv04/disp: fix framebuffer pin refcounting
  drm/nouveau/mc: fix race condition between constructor and request_irq()
  drm/nouveau: fix reclocking on nv40
  drm/nouveau/ltcg: fix allocating memory as free
  drm/nouveau/ltcg: fix ltcg memory initialization after suspend
  drm/nouveau/fb: fix null derefs in nv49 and nv4e init
  drm/i915: Invalidate TLBs for the rings after a reset

Commit 94ae9843 (usb: phy: rename all phy drivers to phy-$name-usb.c)
renamed drivers/usb/phy/otg_fsm.h to drivers/usb/phy/phy-fsm-usb.h
but changed drivers/usb/phy/phy-fsm-usb.c to include not existing
"phy-otg-fsm.h" instead of new "phy-fsm-usb.h". This breaks building:
  ...
  drivers/usb/phy/phy-fsm-usb.c:32:25: fatal error: phy-otg-fsm.h: No such file or directory
  compilation terminated.
  make[3]: *** [drivers/usb/phy/phy-fsm-usb.o] Error 1

This commit also missed to modify drivers/usb/phy/phy-fsl-usb.h
to include new "phy-fsm-usb.h" instead of "otg_fsm.h" resulting
in another build breakage:
  ...
  In file included from drivers/usb/phy/phy-fsl-usb.c:46:0:
  drivers/usb/phy/phy-fsl-usb.h:18:21: fatal error: otg_fsm.h: No such file or directory
  compilation terminated.
  make[3]: *** [drivers/usb/phy/phy-fsl-usb.o] Error 1

Fix both issues.
Signed-off-by: NAnatolij Gustschin <agust@denx.de>
Cc: stable <stable@vger.kernel.org> # 3.10+
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit c1117afb (USB: OHCI: make ohci-pci a separate driver)
neglected to preserve the entries for the pci_suspend and pci_resume
driver callbacks.  As a result, OHCI controllers don't work properly
during suspend and after hibernation.

This patch adds the missing callbacks to the driver.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: NSteve Cotton <steve@s.cotton.clara.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit dcd7b8bd ("staging: comedi: put
module _after_ detach" by myself) reversed a couple of calls in
`comedi_device_attach()` when recovering from an error returned by the
low-level driver's 'attach' handler.  Unfortunately, that introduced a
NULL pointer dereference bug as `dev->driver` is NULL after the call to
`comedi_device_detach()`.   We still have a pointer to the low-level
comedi driver structure in the `driv` variable, so use that instead.
Signed-off-by: NIan Abbott <abbotti@mev.co.uk>
Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge networking fixes from David Miller:

 1) Revert Johannes Berg's genetlink locking fix, because it causes
    regressions.

    Johannes and Pravin Shelar are working on fixing things properly.

 2) Do not drop ipv6 ICMP messages without a redirected header option,
    they are legal.  From Duan Jiong.

 3) Missing error return propagation in probing of via-ircc driver.
    From Alexey Khoroshilov.

 4) Do not clear out broadcast/multicast/unicast/WOL bits in r8169 when
    initializing, from Peter Wu.

 5) realtek phy driver programs wrong interrupt status bit, from
    Giuseppe CAVALLARO.

 6) Fix statistics regression in AF_PACKET code, from Willem de Bruijn.

 7) Bridge code uses wrong bitmap length, from Toshiaki Makita.

 8) SFC driver uses wrong indexes to look up MAC filters, from Ben
    Hutchings.

 9) Don't pass stack buffers into usb control operations in hso driver,
    from Daniel Gimpelevich.

10) Multiple ipv6 fragmentation headers in one packet is illegal and
    such packets should be dropped, from Hannes Frederic Sowa.

11) When TCP sockets are "repaired" as part of checkpoint/restart, the
    timestamp field of SKBs need to be refreshed otherwise RTOs can be
    wildly off.  From Andrey Vagin.

12) Fix memcpy args (uses 'address of pointer' instead of 'pointer') in
    hostp driver.  From Dan Carpenter.

13) nl80211hdr_put() doesn't return an ERR_PTR, but some code believes
    it does.  From Dan Carpenter.

14) Fix regression in wireless SME disconnects, from Johannes Berg.

15) Don't use a stack buffer for DMA in zd1201 USB wireless driver, from
    Jussi Kivilinna.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (33 commits)
  ipv4: expose IPV4_DEVCONF
  ipv6: handle Redirect ICMP Message with no Redirected Header option
  be2net: fix disabling TX in be_close()
  Revert "genetlink: fix family dump race"
  hso: Fix stack corruption on some architectures
  hso: Earlier catch of error condition
  sfc: Fix lookup of default RX MAC filters when steered using ethtool
  bridge: Use the correct bit length for bitmap functions in the VLAN code
  packet: restore packet statistics tp_packets to include drops
  net: phy: rtl8211: fix interrupt on status link change
  r8169: remember WOL preferences on driver load
  via-ircc: don't return zero if via_ircc_open() failed
  macvtap: Ignore tap features when VNET_HDR is off
  macvtap: Correctly set tap features when IFF_VNET_HDR is disabled.
  macvtap: simplify usage of tap_features
  tcp: set timestamps for restored skb-s
  bnx2x: set VF DMAE when first function has 0 supported VFs
  bnx2x: Protect against VFs' ndos when SR-IOV is disabled
  bnx2x: prevent VF benign attentions
  bnx2x: Consider DCBX remote error
  ...

Merge fixes from Andrew Morton:
 "A few fixes.  One is a licensing change and I don't do licensing, so
  please eyeball that one"

Licensing eye-balled.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  lib/lz4: correct the LZ4 license
  memcg: get rid of swapaccount leftovers
  nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection
  nilfs2: remove double bio_put() in nilfs_end_bio_write() for BIO_EOPNOTSUPP error
  drivers/platform/olpc/olpc-ec.c: initialise earlier

The LZ4 code is listed as using the "BSD 2-Clause License".
Signed-off-by: NRichard Laager <rlaager@wiktel.com>
Acked-by: NKyungsik Lee <kyungsik.lee@lge.com>
Cc: Chanho Min <chanho.min@lge.com>
Cc: Richard Yao <ryao@gentoo.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[ The 2-clause BSD can be just converted into GPL, but that's rude and
  pointless, so don't do it   - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The swapaccount kernel parameter without any values has been removed by
commit a2c8990a ("memsw: remove noswapaccount kernel parameter") but
it seems that we didn't get rid of all the left overs.

Make sure that menuconfig help text and kernel-parameters.txt are clear
about value for the paramter and remove the stalled comment which is not
very much useful on its own.
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Reported-by: NGergely Risko <gergely@risko.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the issue with improper counting number of flying bio requests for
BIO_EOPNOTSUPP error detection case.

The sb_nbio must be incremented exactly the same number of times as
complete() function was called (or will be called) because
nilfs_segbuf_wait() will call wail_for_completion() for the number of
times set to sb_nbio:

  do {
      wait_for_completion(&segbuf->sb_bio_event);
  } while (--segbuf->sb_nbio > 0);

Two functions complete() and wait_for_completion() must be called the
same number of times for the same sb_bio_event.  Otherwise,
wait_for_completion() will hang or leak.
Signed-off-by: NVyacheslav Dubeyko <slava@dubeyko.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove double call of bio_put() in nilfs_end_bio_write() for the case of
BIO_EOPNOTSUPP error detection.  The issue was found by Dan Carpenter
and he suggests first version of the fix too.
Signed-off-by: NVyacheslav Dubeyko <slava@dubeyko.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Being a low-level component, various drivers (e.g.  olpc-battery) assume
that it is ok to communicate with the OLPC Embedded Controller during
probe.  Therefore the OLPC EC driver must be initialised before other
drivers try to use it.  This was the case until it was recently moved
out of arch/x86 and restructured around commits ac250415 ("Platform:
OLPC: turn EC driver into a platform_driver") and 85f90cf6 ("x86:
OLPC: switch over to using new EC driver on x86").

Use arch_initcall so that olpc-ec is readied earlier, matching the
previous behaviour.

Fixes a regression introduced in Linux-3.6 where various drivers such as
olpc-battery and olpc-xo1-sci failed to load due to an inability to
communicate with the EC.  The user-visible effect was a lack of battery
monitoring, missing ebook/lid switch input devices, etc.
Signed-off-by: NDaniel Drake <dsd@laptop.org>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Paul Fox <pgf@laptop.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Merge tag 'drm-intel-fixes-2013-08-23' of git://people.freedesktop.org/~danvet/drm-intel into drm-fixes

Just one patch that soaked for quite a bit to fix a resume issue,
resulting in gpu hangs (or worse) due to tlb containing garbage.

* tag 'drm-intel-fixes-2013-08-23' of git://people.freedesktop.org/~danvet/drm-intel:
  drm/i915: Invalidate TLBs for the rings after a reset

IP sends device configuration (see inet_fill_link_af) as an array
in the netlink information, but the indices in that array are not
exposed to userspace through any current santized header file.

It was available back in 2.6.32 (in /usr/include/linux/sysctl.h)
but was broken by:
  commit 02291680
  Author: Eric W. Biederman <ebiederm@xmission.com>
  Date:   Sun Feb 14 03:25:51 2010 +0000

    net ipv4: Decouple ipv4 interface parameters from binary sysctl numbers

Eric was solving the sysctl problem but then the indices were re-exposed
by a later addition of devconf support for IPV4

  commit 9f0f7272
  Author: Thomas Graf <tgraf@infradead.org>
  Date:   Tue Nov 16 04:32:48 2010 +0000

    ipv4: AF_INET link address family

Putting them in /usr/include/linux/ip.h seemed the logical match
for the DEVCONF_ definitions for IPV6 in /usr/include/linux/ip6.h
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

rfc 4861 says the Redirected Header option is optional, so
the kernel should not drop the Redirect Message that has no
Redirected Header option. In this patch, the function
ip6_redirect_no_header() is introduced to deal with that
condition.
Signed-off-by: NDuan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>

commit fba87559 ("disable TX in be_close()") disabled TX in be_close()
to protect be_xmit() from touching freed up queues in the AER recovery
flow.  But, TX must be disabled *before* cleaning up TX completions in
the close() path, not after. This allows be_tx_compl_clean() to free up
all TX-req skbs that were notified to the HW.
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Revert commit c04c697c (ACPI / video: Always call acpi_video_init_brightness()
on init), because it breaks eDP backlight at 1920x1080 on Acer Aspire S3
for Trevor Bortins.

References: https://bugs.freedesktop.org/show_bug.cgi?id=68355Reported-and-bisected-by: NTrevor Bortins <enabfluw@gmail.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Merge in a fix for RX MAC address filter programming bug in the sfc
driver.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 58ad436f.

It turns out that the change introduced a potential deadlock
by causing a locking dependency with netlink's cb_mutex. I
can't seem to find a way to resolve this without doing major
changes to the locking, so revert this.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Acked-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pull x86 platform driver fixes from Matthew Garrett:
 "Three trivial fixes - the first reverts a patch that's broken some
  other devices (again - I'm trying to figure out a clean way to
  implement this), the other two fix minor issues in the sony-laptop
  driver"

* 'linux-next' of git://cavan.codon.org.uk/platform-drivers-x86:
  Revert "hp-wmi: Enable hotkeys on some systems"
  sony-laptop: Fix reporting of gfx_switch_status
  sony-laptop: return a negative error code in sonypi_compat_init()

Pull ARM SoC fixes from Olof Johansson:
 "A handful of fixes for 3.11 are still trickling in.  These are:
   - A couple of fixes for older OMAP platforms
   - Another few fixes for at91 (lateish due to European summer
     vacations)
   - A late-found problem with USB on Tegra, fix is to keep VBUS
     regulator on at all times
   - One fix for Exynos 5440 dealing with CPU detection
   - One MAINTAINERS update"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: tegra: always enable USB VBUS regulators
  ARM: davinci: nand: specify ecc strength
  ARM: OMAP: rx51: change musb mode to OTG
  ARM: OMAP2: fix musb usage for n8x0
  MAINTAINERS: Update email address for Benoit Cousson
  ARM: at91/DT: fix at91sam9n12ek memory node
  ARM: at91: add missing uart clocks DT entries
  ARM: SAMSUNG: fix to support for missing cpu specific map_io
  ARM: at91/DT: at91sam9x5ek: fix USB host property to enable port C