Some bit-rot needs to be cleaned out.
Signed-off-by: NNeilBrown <neilb@suse.de>

Linus asks 'why "raid6" twice?'. No reason.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

More code can be pushed from rwsem_down_read_failed and
rwsem_down_write_failed into rwsem_down_failed_common.

Following change adding down_read_critical infrastructure support also
enjoys having flags available in a register rather than having to fish it
out in the struct rwsem_waiter...
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change addresses the following situation:

- Thread A acquires the rwsem for read
- Thread B tries to acquire the rwsem for write, notices there is already
  an active owner for the rwsem.
- Thread C tries to acquire the rwsem for read, notices that thread B already
  tried to acquire it.
- Thread C grabs the spinlock and queues itself on the wait queue.
- Thread B grabs the spinlock and queues itself behind C. At this point A is
  the only remaining active owner on the rwsem.

In this situation thread B could notice that it was the last active writer
on the rwsem, and decide to wake C to let it proceed in parallel with A
since they both only want the rwsem for read.
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Previously each waiting thread added a bias of RWSEM_WAITING_BIAS.  With
this change, the bias is added only once to indicate that the wait list is
non-empty.

This has a few nice properties which will be used in following changes:
- when the spinlock is held and the waiter list is known to be non-empty,
  count < RWSEM_WAITING_BIAS  <=>  there is an active writer on that sem
- count == RWSEM_WAITING_BIAS  <=>  there are waiting threads and no
                                     active readers/writers on that sem
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In __rwsem_do_wake(), we can skip the active count check unless we come
there from up_xxxx().  Also when checking the active count, it is not
actually necessary to increment it; this allows us to get rid of the read
side undo code and simplify the calculation of the final rwsem count
adjustment once we've counted the reader threads to wake.

The basic observation is the following.  When there are waiter threads on
a rwsem and the spinlock is held, other threads can only increment the
active count by trying to grab the rwsem in down_xxxx().  However
down_xxxx() will notice there are waiter threads and take the down_failed
path, blocking to acquire the spinlock on the way there.  Therefore, a
thread observing an active count of zero with waiters queued and the
spinlock held, is protected against other threads acquiring the rwsem
until it wakes the last waiter or releases the spinlock.
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is in preparation for later changes in the series.

In __rwsem_do_wake(), the first queued waiter is checked first in order to
determine whether it's a writer or a reader.  The code paths diverge at
this point.  The code that checks and increments the rwsem active count is
duplicated on both sides - the point is that later changes in the series
will be able to independently modify both sides.
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Getting and putting arrays of pointers with flex arrays is a PITA.  You
have to remember to pass &ptr to the _put and you have to do weird and
wacky casting to get the ptr back from the _get.  Add two functions
flex_array_get_ptr() and flex_array_put_ptr() to handle all of the magic.

[akpm@linux-foundation.org: simplification suggested by Joe]
Signed-off-by: NEric Paris <eparis@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: James Morris <jmorris@namei.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The strict_strtoul() and strict_strtoull() functions used strlen() to
check argument's length in a situation where it wasn't strictly necessary
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Cc: "Yi Yang" <yi.y.yang@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the magic LIST_POISON* values to detect an incorrect use of list_del
on a deleted entry.  This DEBUG_LIST specific warning is easier to
understand than the generic Oops message caused by LIST_POISON
dereference.
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A profile of a network benchmark showed iommu_num_pages rather high up:

     0.52%  iommu_num_pages

Looking at the profile, an integer divide is taking almost all of the time:

      %
         :      c000000000376ea4 <.iommu_num_pages>:
    1.93 :      c000000000376ea4:       fb e1 ff f8     std     r31,-8(r1)
    0.00 :      c000000000376ea8:       f8 21 ff c1     stdu    r1,-64(r1)
    0.00 :      c000000000376eac:       7c 3f 0b 78     mr      r31,r1
    3.86 :      c000000000376eb0:       38 84 ff ff     addi    r4,r4,-1
    0.00 :      c000000000376eb4:       38 05 ff ff     addi    r0,r5,-1
    0.00 :      c000000000376eb8:       7c 84 2a 14     add     r4,r4,r5
   46.95 :      c000000000376ebc:       7c 00 18 38     and     r0,r0,r3
   45.66 :      c000000000376ec0:       7c 84 02 14     add     r4,r4,r0
    0.00 :      c000000000376ec4:       7c 64 2b 92     divdu   r3,r4,r5
    0.00 :      c000000000376ec8:       38 3f 00 40     addi    r1,r31,64
    0.00 :      c000000000376ecc:       eb e1 ff f8     ld      r31,-8(r1)
    1.61 :      c000000000376ed0:       4e 80 00 20     blr

Since every caller of iommu_num_pages passes in a constant power of two
we can inline this such that the divide is replaced by a shift. The
entire function is only a few instructions once optimised, so it is
a good candidate for inlining overall.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Implement function for setting one tag if another tag is set for each item
in given range.
Signed-off-by: NJan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add percpu_counter_compare that allows for a quick but accurate comparison
of percpu_counter with a given value.

A rough count is provided by the count field in percpu_counter structure,
without accounting for the other values stored in individual cpu counters.

The actual count is a sum of count and the cpu counters.  However, count
field is never different from the actual value by a factor of
batch*num_online_cpu.  We do not need to get actual count for comparison
if count is different from the given value by this factor and allows for
quick comparison without summing up all the per cpu counters.
Signed-off-by: NTim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

debugfs no longer uses 'kernel_subsys' (which is gone), and other
kernel/ksysfs.c code is always built, so DEBUG_FS does not need
to depend on SYSFS.

Fixes this kconfig warning:

warning: (TREE_RCU_TRACE || AMD_IOMMU_STATS && AMD_IOMMU || MTD_UBI_DEBUG && MTD && SYSFS && MTD_UBI || UBIFS_FS_DEBUG && MISC_FILESYSTEMS && UBIFS_FS || DEBUG_KMEMLEAK && DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE) && SYSFS || TRACING || X86_PTDUMP && DEBUG_KERNEL || BLK_DEV_IO_TRACE && TRACING_SUPPORT && FTRACE && SYSFS && BLOCK) selects DEBUG_FS which has unmet direct dependencies (SYSFS)
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Microblaze doesn't support frame pointers. Ftrace code
uses CALLER_ADDR1 which is defined in linux/ftrace.h. For Microblaze
is 0.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

kmemleak ignores page_alloc() and so believes the final sub-page
allocation using the plain kmalloc is decoupled and lost. This leads to
lots of false-positives with code that uses scatterlists.

The options seem to be either to tell kmemleak that the kmalloc is not
leaked or to notify kmemleak of the page allocations. The danger of the
first approach is that we may hide a real leak, so choose the latter
approach (of which I am not sure of the downsides).

v2: Added comments on the suggestion of Catalin.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

ARM has support for the atomic64_dec_if_positive operation
so ensure that it is tested by the atomic64_test routine.
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The last 't' of 'fault' is missing in the description of FAIL_IO_TIMEOUT.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Introduce a new DEBUG_KMEMLEAK_DEFAULT_OFF config parameter that allows
kmemleak to be disabled by default, but enabled on the command line
via: kmemleak=on. Although a reboot is required to turn it on, its still
useful to not require a re-compile.
Signed-off-by: NJason Baron <jbaron@redhat.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>

Newer gcc has a -femit-struct-debug-baseonly option that dramatically
reduces the size of object files with debug info. What it does
is to only emit type information for structures when the structures
are defined in the same file or in a header file.

This means the type information for most headers are not included.
This is not good when the type information is actually
needed (e.g. with kgdb or systemtap)

But often kernel hackers only care about line numbers and don't
need all the type information anyways. In this case setting
the option can be a big win:

A build dir for a specific x86-64 configuration with gcc 4.5
shrunk from 2.3G to 1.2G. The compilation was also nearly a minute
faster.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
[mmarek: reformatted help text]
Signed-off-by: NMichal Marek <mmarek@suse.cz>

via following scripts

      FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

      sed -i \
        -e 's/lmb/memblock/g' \
        -e 's/LMB/MEMBLOCK/g' \
        $FILES

      for N in $(find . -name lmb.[ch]); do
        M=$(echo $N | sed 's/lmb/memblock/g')
        mv $N $M
      done

and remove some wrong change like lmbench and dlmb etc.

also move memblock.c from lib/ to mm/
Suggested-by: NIngo Molnar <mingo@elte.hu>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

'Unamp' should be 'Unmap'.
Signed-off-by: NKulikov Vasiliy <segooon@gmail.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Current x86 ioremap() doesn't handle physical address higher than
32-bit properly in X86_32 PAE mode. When physical address higher than
32-bit is passed to ioremap(), higher 32-bits in physical address is
cleared wrongly. Due to this bug, ioremap() can map wrong address to
linear address space.

In my case, 64-bit MMIO region was assigned to a PCI device (ioat
device) on my system. Because of the ioremap()'s bug, wrong physical
address (instead of MMIO region) was mapped to linear address space.
Because of this, loading ioatdma driver caused unexpected behavior
(kernel panic, kernel hangup, ...).
Signed-off-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
LKML-Reference: <4C1AE680.7090408@jp.fujitsu.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Reimplement augmented RB-trees without sprinkling extra branches
all over the RB-tree code (which lives in the scheduler hot path).

This approach is 'borrowed' from Fabio's BFQ implementation and
relies on traversing the rebalance path after the RB-tree-op to
correct the heap property for insertion/removal and make up for
the damage done by the tree rotations.

For insertion the rebalance path is trivially that from the new
node upwards to the root, for removal it is that from the deepest
node in the path from the to be removed node that will still
be around after the removal.

[ This patch also fixes a video driver regression reported by
  Ali Gholami Rudi - the memtype->subtree_max_end was updated
  incorrectly. ]
Acked-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Acked-by: NVenkatesh Pallipadi <venki@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: NAli Gholami Rudi <ali@rudi.ir>
Cc: Fabio Checconi <fabio@gandalf.sssup.it>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1275414172.27810.27961.camel@twins>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed a #ifdef)
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add the ability to print a format and va_list from a structure pointer

Allows __dev_printk to be implemented as a single printk while
minimizing string space duplication.

%pV should not be used without some mechanism to verify the
format and argument use ala __attribute__(format (printf(...))).
Signed-off-by: NJoe Perches <joe@perches.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

bitmap_find_next_zero_area requires the size of the bitmap, we instead
passed the last suitable position.  This made it impossible to allocate
from the end of the pool.

Fixes a regression introduced by 243797f5
("genalloc: use bitmap_find_next_zero_area").
Signed-off-by: NImre Deak <imre.deak@nokia.com>
Cc: Zygo Blaxell <zygo.blaxell@xandros.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert to rcu_dereference_raw() given that many callers may have many
different locking models.
Located-by: NMiles Lane <miles.lane@gmail.com>
Tested-by: NMiles Lane <miles.lane@gmail.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Helps finding racy users of call_rcu(), which results in hangs because list
entries are overwritten and/or skipped.

Changelog since v4:
- Bissectability is now OK
- Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to
  call_rcu(). Statically initialized objects are detected with
  object_is_static().
- Rename rcu_head_init_on_stack to init_rcu_head_on_stack.
- Remove init_rcu_head() completely.

Changelog since v3:
- Include comments from Lai Jiangshan

This new patch version is based on the debugobjects with the newly introduced
"active state" tracker.

Non-initialized entries are all considered as "statically initialized". An
activation fixup (triggered by call_rcu()) takes care of performing the debug
object initialization without issuing any warning. Since we cannot increase the
size of struct rcu_head, I don't see much room to put an identifier for
statically initialized rcu_head structures. So for now, we have to live without
"activation without explicit init" detection. But the main purpose of this debug
option is to detect double-activations (double call_rcu() use of a rcu_head
before the callback is executed), which is correctly addressed here.

This also detects potential internal RCU callback corruption, which would cause
the callbacks to be executed twice.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: David S. Miller <davem@davemloft.net>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NLai Jiangshan <laijs@cn.fujitsu.com>

We put the functions dealing with the operations on
the SWIOTLB buffer in the header and make those functions non-static.
And also make the functions exported via EXPORT_SYMBOL_GPL.

See "swiotlb: swiotlb: add swiotlb_tbl_map_single library function" for
full description of patchset.

[v2: swiotlb_sync_single_range_for_* no more. Remove usage.]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Tested-by: NAlbert Herranz <albert_herranz@yahoo.es>

.. to catch anybody doing something funky.

See "swiotlb: swiotlb: add swiotlb_tbl_map_single library function" for
full description of patchset.

[v2: swiotlb_sync_single_range_* no more - removed usage]
[v3: enum dma_data_direction direction -> enum dma_data_direction dir]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Tested-by: NAlbert Herranz <albert_herranz@yahoo.es>

The functions that operate on io_tlb_list/io_tlb_start/io_tlb_orig_addr
have the prefix 'swiotlb_tbl' now.

See "swiotlb: swiotlb: add swiotlb_tbl_map_single library function" for
full description of patchset.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Tested-by: NAlbert Herranz <albert_herranz@yahoo.es>

This enables the caller to initialize swiotlb with its own iotlb
memory.

See "swiotlb: swiotlb: add swiotlb_tbl_map_single library function" for
full description of patchset.

[v2: changed ..with_tlb to ..with_tbl]
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: NAlbert Herranz <albert_herranz@yahoo.es>

swiotlb_tbl_map_single() takes the dma address of iotlb instead of
using swiotlb_virt_to_bus().

[v2: changed swiotlb_tlb to swiotlb_tbl]
[v3: changed u64 to dma_addr_t]

This patch:

This is a set of patches that separate the address translation
(virt_to_phys, virt_to_bus, etc) and allocation of the SWIOTLB buffer
from the SWIOTLB library.

The idea behind this set of patches is to make it possible to have separate
mechanisms for translating virtual to physical or virtual to DMA addresses
on platforms which need an SWIOTLB, and where physical != PCI bus address
and also to allocate the core IOTLB memory outside SWIOTLB.

One customers of this is the pv-ops project, which can switch between
different modes of operation depending on the environment it is running in:
bare-metal or virtualized (Xen for now). Another is the Wii DMA - used to
implement the MEM2 DMA facility needed by its EHCI controller (for details:
http://lkml.org/lkml/2010/5/18/303)

On bare-metal SWIOTLB is used when there are no hardware IOMMU. In virtualized
environment it used when PCI pass-through is enabled for the guest. The problems
with PCI pass-through is that the guest's idea of PFN's is not the real thing.
To fix that, there is translation layer for PFN->machine frame number and vice-versa.
To bubble that up to the SWIOTLB layer there are two possible solutions.

One solution has been to wholesale copy the SWIOTLB, stick it in
arch/x86/xen/swiotlb.c and modify the virt_to_phys, phys_to_virt and others
to use the Xen address translation functions. Unfortunately, since the kernel can
run on bare-metal, there would be big code overlap with the real SWIOTLB.
(git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git xen/dom0/swiotlb-new)

Another approach, which this set of patches explores, is to abstract the
address translation and address determination functions away from the
SWIOTLB book-keeping functions. This way the core SWIOTLB library functions
are present in one place, while the address related functions are in
a separate library that can be loaded when running under non-bare-metal platform.

Changelog:
Since the last posting [v8.2] Konrad has done:
 - Added this changelog in the patch and referenced in the other patches
   this description.
 - 'enum dma_data_direction direction' to 'enum dma.. dir' so to be
   unified.
[v8-v8.2 changes:]
 - Rolled-up the last two patches in one.
 - Rebased against linus latest. That meant dealing with swiotlb_sync_single_range_* changes.
 - added Acked-by: Fujita Tomonori and Tested-by: Albert Herranz
[v7-v8 changes:]
 - Minimized the list of exported functions.
 - Integrated Fujita's patches and changed "swiotlb_tlb" to "swiotlb_tbl" in them.
[v6-v7 changes:]
 - Minimized the amount of exported functions/variable with a prefix of: "swiotbl_tbl".
 - Made the usage of 'int dir' to be 'enum dma_data_direction'.
[v5-v6 changes:]
 - Made the exported functions/variables have the 'swiotlb_bk' prefix.
 - dropped the checkpatches/other reworks
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: NAlbert Herranz <albert_herranz@yahoo.es>

Add s390 to list of architectures that have atomic64_dec_if_positive
implemented so we get rid of this warning:

lib/atomic64_test.c:129:2: warning: #warning Please implement
atomic64_dec_if_positive for your architecture, and add it to the IF above
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Luca Barbieri <luca@luca-barbieri.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is a kfree(ue_sk) missing on the error path if
netlink_kernel_create() fails.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Reviewed-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

lib/kobject_uevent.c:87: warning: 'kobj_bcast_filter' defined but not used

Repairs "hotplug: netns aware uevent_helper"

Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This reverts commit 0ac0c0d0, which
caused cross-architecture build problems for all the wrong reasons.
IA64 already added its own version of __node_random(), but the fact is,
there is nothing architectural about the function, and the original
commit was just badly done. Revert it, since no fix is forthcoming.
Requested-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

radix_tree_prev_hole() used LONG_MAX to detect underflow; however,
ULONG_MAX is clearly what was intended, both here and by its only user
(count_history_pages at mm/readahead.c).
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NCesar Eduardo Barros <cesarb@cesarb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>