Put empty or trivial inline stub functions on one line when they fit.  No
functional change.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Consistently use the:

    #ifdef CONFIG_PCI_FOO
    int pci_foo(...);
    #else
    static inline int pci_foo(...) { return -1; }
    #endif

pattern, instead of sometimes using "#ifndef CONFIG_PCI_FOO".

No functional change.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

This change adds two macros to extract the encoded bus and segment
numbers from the HEST Bus field.
Signed-off-by: NBetty Dall <betty.dall@hp.com>
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Using 'make namespacecheck' identify code which should be declared static.
Checked for users in other driver/archs as well.  Compile tested only.

This stops exporting the following interfaces to modules:

    pci_target_state()
    pci_load_saved_state()

[bhelgaas: retained pci_find_next_ext_capability() and pci_cfg_space_size()]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This removes this unused and deprecated interface:

    alloc_pci_dev()

[bhelgaas: split to separate patch]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts part of f46753c5 ("PCI: introduce pci_slot") and
d25b7c8d ("PCI: rename pci_update_slot_number to pci_renumber_slot"),
removing this interface:

    pci_renumber_slot()

[bhelgaas: split to separate patch, add historical link from Alex]
Link: http://lkml.kernel.org/r/20081009043140.8678.44164.stgit@bob.kioSigned-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NAlex Chiang <achiang@canonical.com>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts part of 3e1b1600 ("ACPI/PCI: PCIe ASPM _OSC support
capabilities called when root bridge added"), removing this interface:

    pcie_aspm_enabled()

[bhelgaas: split to separate patch]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Andrew Patterson <andrew.patterson@hp.com>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts db567943 ("PCI: add interface to set visible size of
VPD"), removing this interface:

    pci_vpd_truncate()

[bhelgaas: split to separate patch, also remove prototype from pci.h]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts b48d4425 ("PCI: add ID-based ordering enable/disable
support"), removing these interfaces:

    pci_enable_ido()
    pci_disable_ido()

[bhelgaas: split to separate patch, also remove prototypes from pci.h]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts 48a92a81 ("PCI: add OBFF enable/disable support"),
removing these interfaces:

    pci_enable_obff()
    pci_disable_obff()

[bhelgaas: split to separate patch, also remove prototypes from pci.h]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts 51c2e0a7 ("PCI: add latency tolerance reporting
enable/disable support"), removing these interfaces:

    pci_enable_ltr()
    pci_disable_ltr()
    pci_set_ltr()

[bhelgaas: split to separate patch, also remove prototypes from pci.h]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts parts of c320b976 ("PCI: Add implementation for PRI
capability"), removing these interfaces:

    pci_pri_enabled()
    pci_pri_stopped()
    pci_pri_status()

[bhelgaas: split to separate patch]
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Joerg Roedel <joro@8bytes.org>

When allocating space for 32-bit BARs, we previously limited RESOURCE
addresses so they would fit in 32 bits.  However, the BUS address need not
be the same as the resource address, and it's the bus address that must fit
in the 32-bit BAR.

This patch adds:

  - pci_clip_resource_to_region(), which clips a resource so it contains
    only the range that maps to the specified bus address region, e.g., to
    clip a resource to 32-bit bus addresses, and

  - pci_bus_alloc_from_region(), which allocates space for a resource from
    the specified bus address region,

and changes pci_bus_alloc_resource() to allocate space for 64-bit BARs from
the entire bus address region, and space for 32-bit BARs from only the bus
address region below 4GB.

If we had this window:

  pci_root HWP0002:0a: host bridge window [mem 0xf0180000000-0xf01fedfffff] (bus address [0x80000000-0xfedfffff])

we previously could not put a 32-bit BAR there, because the CPU addresses
don't fit in 32 bits.  This patch fixes this, so we can use this space for
32-bit BARs.

It's also possible (though unlikely) to have resources with 32-bit CPU
addresses but bus addresses above 4GB.  In this case the previous code
would allocate space that a 32-bit BAR could not map.

Remove PCIBIOS_MAX_MEM_32, which is no longer used.

[bhelgaas: reworked starting from http://lkml.kernel.org/r/1386658484-15774-3-git-send-email-yinghai@kernel.org]
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

This adds pci_enable_msi_range(), which supersedes the pci_enable_msi()
and pci_enable_msi_block() MSI interfaces.

It also adds pci_enable_msix_range(), which supersedes the
pci_enable_msix() MSI-X interface.

The old interfaces have three categories of return values:

    negative: failure; caller should not retry
    positive: failure; value indicates number of interrupts that *could*
	have been allocated, and caller may retry with a smaller request
    zero: success; at least as many interrupts allocated as requested

It is error-prone to handle these three cases correctly in drivers.

The new functions return either a negative error code or a number of
successfully allocated MSI/MSI-X interrupts, which is expected to lead to
clearer device driver code.

pci_enable_msi(), pci_enable_msi_block() and pci_enable_msix() still exist
unchanged, but are deprecated and may be removed after callers are updated.

[bhelgaas: tweak changelog]
Suggested-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTejun Heo <tj@kernel.org>

This creates an MSI-X counterpart for pci_msi_vec_count().  Device drivers
can use this function to obtain maximum number of MSI-X interrupts the
device supports and use that number in a subsequent call to
pci_enable_msix().

pci_msix_vec_count() supersedes pci_msix_table_size() and returns a
negative errno if device does not support MSI-X interrupts.  After this
update, callers must always check the returned value.

The only user of pci_msix_table_size() was the PCI-Express port driver,
which is also updated by this change.
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTejun Heo <tj@kernel.org>

The new pci_msi_vec_count() interface makes pci_enable_msi_block_auto()
superfluous.

Drivers can use pci_msi_vec_count() to learn the maximum number of MSIs
supported by the device, and then call pci_enable_msi_block().

pci_enable_msi_block_auto() was introduced recently, and its only user is
the AHCI driver, which is also updated by this change.
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NTejun Heo <tj@kernel.org>

Device drivers can use this interface to obtain the maximum number of MSI
interrupts the device supports and use that number, e.g., in a subsequent
call to pci_enable_msi_block().
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTejun Heo <tj@kernel.org>

We store BAR information as a struct resource, which contains the CPU
address, not the bus address.  Drivers often need the bus address, and
there's currently no convenient way to get it, so they often read the
BAR directly, or use the resource address (which doesn't work if there's
any translation between CPU and bus addresses).

Add pci_bus_address() to make this convenient.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

These interfaces:

  pcibios_resource_to_bus(struct pci_dev *dev, *bus_region, *resource)
  pcibios_bus_to_resource(struct pci_dev *dev, *resource, *bus_region)

took a pci_dev, but they really depend only on the pci_bus.  And we want to
use them in resource allocation paths where we have the bus but not a
device, so this patch converts them to take the pci_bus instead of the
pci_dev:

  pcibios_resource_to_bus(struct pci_bus *bus, *bus_region, *resource)
  pcibios_bus_to_resource(struct pci_bus *bus, *resource, *bus_region)

In fact, with standard PCI-PCI bridges, they only depend on the host
bridge, because that's the only place address translation occurs, but
we aren't going that far yet.

[bhelgaas: changelog]
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Struct pci_bus_region contains bus addresses, which are type dma_addr_t,
not resource_size_t.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Make pci_enable_msi_block(), pci_enable_msi_block_auto() and
pci_enable_msix() consistent with regard to the type of 'nvec' argument.
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTejun Heo <tj@kernel.org>

Suggested-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTejun Heo <tj@kernel.org>

The PCI MSI sysfs code is a mess with kobjects for things that don't really
need to be kobjects.  This patch creates attributes dynamically for the MSI
interrupts instead of using kobjects.

Note, this removes a directory from sysfs.  Old MSI kobjects:

  pci_device
     └── msi_irqs
         └── 40
             └── mode

New MSI attributes:

  pci_device
     └── msi_irqs
         └── 40

As there was only one file "mode" with the kobject model, the interrupt
number is now a file that returns the "mode" of the interrupt (msi vs.
msix).
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>

These are set of two capability registers, it's pretty much given that
they're registers, so reflect their purpose in the name.
Suggested-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

While we don't really have any infrastructure for making use of VC
support, the system BIOS can configure the topology to non-default
VC values prior to boot.  This may be due to silicon bugs, desire to
reserve traffic classes, or perhaps just BIOS bugs.  When we reset
devices, the VC configuration may return to default values, which can
be incompatible with devices upstream.  For instance, Nvidia GRID
cards provide a PCIe switch and some number of GPUs, all supporting
VC.  The power-on default for VC is to support TC0-7 across VC0,
however some platforms will only enable TC0/VC0 mapping across the
topology.  When we do a secondary bus reset on the downstream switch
port, the GPU is reset to a TC0-7/VC0 mapping while the opposite end
of the link only enables TC0/VC0.  If the GPU attempts to use TC1-7,
it fails.

This patch attempts to provide complete support for VC save/restore,
even beyond the minimally required use case above.  This includes
save/restore and reload of the arbitration table, save/restore and
reload of the port arbitration tables, and re-enabling of the
channels for VC, VC9, and MFVC capabilities.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Current save/restore is specific to standard capabilities.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

We currently have two instance of this loop which waits for a pending bit
to clear in a status dword.  Generalize the function for future users.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Add symbolic constants for the PCIe Slot Control indicator and power
control fields defined by spec and use them instead of open-coded hex
constants.

No functional change.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Prefer use of the direct definition of struct pci_device_id instead of
indirection via macro DEFINE_PCI_DEVICE_TABLE.

Update the PCI documentation to deprecate DEFINE_PCI_DEVICE_TABLE.  Update
checkpatch adding --fix option.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NJingoo Han <jg1.han@samsung.com>

Change x86_msi.restore_msi_irqs(struct pci_dev *dev, int irq) to
x86_msi.restore_msi_irqs(struct pci_dev *dev).

restore_msi_irqs() restores multiple MSI-X IRQs, so param 'int irq' is
unneeded.  This makes code more consistent between vm and bare metal.

Dom0 MSI-X restore code can also be optimized as XEN only has a hypercall
to restore all MSI-X vectors at one time.
Tested-by: NSucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: NZhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Add a flag to tell the PCI subsystem that kernel is shutting down in
preparation to kexec a kernel.  Add code in PCI subsystem to use this flag
to clear Bus Master bit on PCI devices only in case of kexec reboot.

This fixes a power-off problem on Acer Aspire V5-573G and likely other
machines and avoids any other issues caused by clearing Bus Master bit on
PCI devices in normal shutdown path.  The problem was introduced by
b566a22c ("PCI: disable Bus Master on PCI device shutdown").

This patch is based on discussion at
http://marc.info/?l=linux-pci&m=138425645204355&w=2

Link: https://bugzilla.kernel.org/show_bug.cgi?id=63861Reported-by: NChang Liu <cl91tp@gmail.com>
Signed-off-by: NKhalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Cc: stable@vger.kernel.org	# v3.5+

Pasting the verbatim PCI_(VENDOR|DEVICE)_* macros in the __pci_fixup_*
symbol names results in insanely long names such as

__pci_fixup_resumePCI_VENDOR_ID_SERVERWORKSPCI_DEVICE_ID_SERVERWORKS_HT1000SBquirk_disable_broadcom_boot_interrupt

When Link-Time Optimization adds its numeric suffix to such symbol, it
overflows the namebuf[KSYM_NAME_LEN] array in kernel/kallsyms.c.  Use the
line number instead to create (nearly) unique symbol names.
Reported-by: NJoe Mario <jmario@redhat.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Andi Kleen <ak@linux.intel.com>

I don't know what went wrong, mis-merge or something, but ->pmd_huge_pte
placed in wrong union within struct page.

In original patch[1] it's placed to union with ->lru and ->slab, but in
commit e009bb30 ("mm: implement split page table lock for PMD
level") it's in union with ->index and ->freelist.

That union seems also unused for pages with table tables and safe to
re-use, but it's not what I've tested.

Let's move it to original place.  It fixes indentation at least.  :)

[1] https://lkml.org/lkml/2013/10/7/288Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 7cb2ef56 ("mm: fix aio performance regression for database
caused by THP") can cause dereference of a dangling pointer if
split_huge_page runs during PageHuge() if there are updates to the
tail_page->private field.

Also it is repeating compound_head twice for hugetlbfs and it is running
compound_head+compound_trans_head for THP when a single one is needed in
both cases.

The new code within the PageSlab() check doesn't need to verify that the
THP page size is never bigger than the smallest hugetlbfs page size, to
avoid memory corruption.

A longstanding theoretical race condition was found while fixing the
above (see the change right after the skip_unlock label, that is
relevant for the compound_lock path too).

By re-establishing the _mapcount tail refcounting for all compound
pages, this also fixes the below problem:

  echo 0 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

  BUG: Bad page state in process bash  pfn:59a01
  page:ffffea000139b038 count:0 mapcount:10 mapping:          (null) index:0x0
  page flags: 0x1c00000000008000(tail)
  Modules linked in:
  CPU: 6 PID: 2018 Comm: bash Not tainted 3.12.0+ #25
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
    dump_stack+0x55/0x76
    bad_page+0xd5/0x130
    free_pages_prepare+0x213/0x280
    __free_pages+0x36/0x80
    update_and_free_page+0xc1/0xd0
    free_pool_huge_page+0xc2/0xe0
    set_max_huge_pages.part.58+0x14c/0x220
    nr_hugepages_store_common.isra.60+0xd0/0xf0
    nr_hugepages_store+0x13/0x20
    kobj_attr_store+0xf/0x20
    sysfs_write_file+0x189/0x1e0
    vfs_write+0xc5/0x1f0
    SyS_write+0x55/0xb0
    system_call_fastpath+0x16/0x1b
Signed-off-by: NKhalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Tested-by: NKhalid Aziz <khalid.aziz@oracle.com>
Cc: Pravin Shelar <pshelar@nicira.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Right now, the migration code in migrate_page_copy() uses copy_huge_page()
for hugetlbfs and thp pages:

       if (PageHuge(page) || PageTransHuge(page))
                copy_huge_page(newpage, page);

So, yay for code reuse.  But:

  void copy_huge_page(struct page *dst, struct page *src)
  {
        struct hstate *h = page_hstate(src);

and a non-hugetlbfs page has no page_hstate().  This works 99% of the
time because page_hstate() determines the hstate from the page order
alone.  Since the page order of a THP page matches the default hugetlbfs
page order, it works.

But, if you change the default huge page size on the boot command-line
(say default_hugepagesz=1G), then we might not even *have* a 2MB hstate
so page_hstate() returns null and copy_huge_page() oopses pretty fast
since copy_huge_page() dereferences the hstate:

  void copy_huge_page(struct page *dst, struct page *src)
  {
        struct hstate *h = page_hstate(src);
        if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
  ...

Mel noticed that the migration code is really the only user of these
functions.  This moves all the copy code over to migrate.c and makes
copy_huge_page() work for THP by checking for it explicitly.

I believe the bug was introduced in commit b32967ff ("mm: numa: Add
THP migration for the NUMA working set scanning fault case")

[akpm@linux-foundation.org: fix coding-style and comment text, per Naoya Horiguchi]
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Reviewed-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Tested-by: NDave Jiang <dave.jiang@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix another really stupid bug - I introduced genl_set_err()
precisely to be able to adjust the group and reject invalid
ones, but then forgot to do so.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Unfortunately, I introduced a tremendously stupid bug into
genlmsg_multicast() when doing all those multicast group
changes: it adjusts the group number, but then passes it
to genlmsg_multicast_netns() which does that again.

Somehow, my tests failed to catch this, so add a warning
into genlmsg_multicast_netns() and remove the offending
group ID adjustment.

Also add a warning to the similar code in other functions
so people who misuse them are more loudly warned.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add auto-MDI/MDI-X capability for forced (autonegotiation disabled)
10/100 Mbps speeds on Vitesse VSC82x4 PHYs. Exported previously static
function genphy_setup_forced() required by the new config_aneg handler
in the Vitesse PHY module.
Signed-off-by: NMadalin Bucur <madalin.bucur@freescale.com>
Signed-off-by: NShruti Kanetkar <Shruti@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch now always passes msg->msg_namelen as 0. recvmsg handlers must
set msg_namelen to the proper size <= sizeof(struct sockaddr_storage)
to return msg_name to the user.

This prevents numerous uninitialized memory leaks we had in the
recvmsg handlers and makes it harder for new code to accidentally leak
uninitialized memory.

Optimize for the case recvfrom is called with NULL as address. We don't
need to copy the address at all, so set it to NULL before invoking the
recvmsg handler. We can do so, because all the recvmsg handlers must
cope with the case a plain read() is called on them. read() also sets
msg_name to NULL.

Also document these changes in include/linux/net.h as suggested by David
Miller.

Changes since RFC:

Set msg->msg_name = NULL if user specified a NULL in msg_name but had a
non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't
affect sendto as it would bail out earlier while trying to copy-in the
address. It also more naturally reflects the logic by the callers of
verify_iovec.

With this change in place I could remove "
if (!uaddr || msg_sys->msg_namelen == 0)
	msg->msg_name = NULL
".

This change does not alter the user visible error logic as we ignore
msg_namelen as long as msg_name is NULL.

Also remove two unnecessary curly brackets in ___sys_recvmsg and change
comments to netdev style.

Cc: David Miller <davem@davemloft.net>
Suggested-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Doing an if statement to test some condition to know if we should
trigger a tracepoint is pointless when tracing is disabled. This just
adds overhead and wastes a branch prediction. This is why the
TRACE_EVENT_CONDITION() was created. It places the check inside the jump
label so that the branch does not happen unless tracing is enabled.

That is, instead of doing:

	if (em)
		trace_btrfs_get_extent(root, em);

Which is basically this:

	if (em)
		if (static_key(trace_btrfs_get_extent)) {

Using a TRACE_EVENT_CONDITION() we can just do:

	trace_btrfs_get_extent(root, em);

And the condition trace event will do:

	if (static_key(trace_btrfs_get_extent)) {
		if (em) {
			...

The static key is a non conditional jump (or nop) that is faster than
having to check if em is NULL or not.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>