This is the main workhorse that deals with semop user calls such that
the waitforzero or semval update operations, on the set, can complete on
not as the sma currently stands.  Currently, the set is iterated twice
(setting semval, then backwards for the sempid value).  Slowpaths, and
particularly SEM_UNDO calls, must undo any altered sem when it is
detected that the caller must block or has errored-out.

With larger sets, there can occur situations where this involves a lot
of cycles and can obviously be a suboptimal use of cached resources in
shared memory.  Ie, discarding CPU caches that are also calling semop
and have the sembuf cached (and can complete), while the current lock
holder doing the semop will block, error, or does a waitforzero
operation.

This patch proposes still iterating the set twice, but the first scan is
read-only, and we perform the actual updates afterward, once we know
that the call will succeed.  In order to not suffer from the overhead of
dealing with sops that act on the same sem_num, such (rare) cases use
perform_atomic_semop_slow(), which is exactly what we have now.
Duplicates are detected before grabbing sem_lock, and uses simple a
32/64-bit hash array variable to based on the sem_num we are working on.

In addition add some comments to when we expect to the caller to block.

[akpm@linux-foundation.org: coding-style fixes]
[colin.king@canonical.com: ensure we left shift a ULL rather than a 32 bit integer]
  Link: http://lkml.kernel.org/r/20161028181129.7311-1-colin.king@canonical.com
Link: http://lkml.kernel.org/r/20160921194603.GB21438@linux-80c1.suseSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Our sysv sems have been using the notion of lockless wakeups for a
while, ever since commit 0a2b9d4c ("ipc/sem.c: move wake_up_process
out of the spinlock section"), in order to reduce the sem_lock hold
times.  This in-house pending queue can be replaced by wake_q (just like
all the rest of ipc now), in that it provides the following advantages:

 o Simplifies and gets rid of unnecessary code.

 o We get rid of the IN_WAKEUP complexities. Given that wake_q_add()
   grabs reference to the task, if awoken due to an unrelated event,
   between the wake_q_add() and wake_up_q() window, we cannot race with
   sys_exit and the imminent call to wake_up_process().

 o By not spinning IN_WAKEUP, we no longer need to disable preemption.

In consequence, the wakeup paths (after schedule(), that is) must
acknowledge an external signal/event, as well spurious wakeup occurring
during the pending wakeup window.  Obviously no changes in semantics
that could be visible to the user.  The fastpath is _only_ for when we
know for sure that we were awoken due to a the waker's successful semop
call (queue.status is not -EINTR).

On a 48-core Haswell, running the ipcscale 'waitforzero' test, the
following is seen with increasing thread counts:

                               v4.8-rc5                v4.8-rc5
                                                        semopv2
Hmean    sembench-sem-2      574733.00 (  0.00%)   578322.00 (  0.62%)
Hmean    sembench-sem-8      811708.00 (  0.00%)   824689.00 (  1.59%)
Hmean    sembench-sem-12     842448.00 (  0.00%)   845409.00 (  0.35%)
Hmean    sembench-sem-21     933003.00 (  0.00%)   977748.00 (  4.80%)
Hmean    sembench-sem-48     935910.00 (  0.00%)  1004759.00 (  7.36%)
Hmean    sembench-sem-79     937186.00 (  0.00%)   983976.00 (  4.99%)
Hmean    sembench-sem-234    974256.00 (  0.00%)  1060294.00 (  8.83%)
Hmean    sembench-sem-265    975468.00 (  0.00%)  1016243.00 (  4.18%)
Hmean    sembench-sem-296    991280.00 (  0.00%)  1042659.00 (  5.18%)
Hmean    sembench-sem-327    975415.00 (  0.00%)  1029977.00 (  5.59%)
Hmean    sembench-sem-358   1014286.00 (  0.00%)  1049624.00 (  3.48%)
Hmean    sembench-sem-389    972939.00 (  0.00%)  1043127.00 (  7.21%)
Hmean    sembench-sem-420    981909.00 (  0.00%)  1056747.00 (  7.62%)
Hmean    sembench-sem-451    990139.00 (  0.00%)  1051609.00 (  6.21%)
Hmean    sembench-sem-482    965735.00 (  0.00%)  1040313.00 (  7.72%)

[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: merge fix for WAKE_Q to DEFINE_WAKE_Q rename]
  Link: http://lkml.kernel.org/r/20161122210410.5eca9fc2@canb.auug.org.au
Link: http://lkml.kernel.org/r/1474225896-10066-3-git-send-email-dave@stgolabs.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Acked-by: NManfred Spraul <manfred@colorfullife.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ipc/sem: do not call wake_sem_queue_do() prematurely ... as this call should obviously be paired with its _prepare()

counterpart.  At least whenever possible, as there is no harm in calling
it bogusly as we do now in a few places.  Immediate error semop(2) paths
that are far from ever having the task block can be simplified and avoid
a few unnecessary loads on their way out of the call as it is not deeply
nested.

Link: http://lkml.kernel.org/r/1474225896-10066-2-git-send-email-dave@stgolabs.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Implement functions watchdog_nmi_enable and watchdog_nmi_disable to
enable/disable nmi watchdog.  Sparc uses arch specific nmi watchdog
handler.  Currently, we do not have a way to enable/disable nmi watchdog
dynamically.  With these patches we can enable or disable arch specific
nmi watchdogs using proc or sysctl interface.

Example commands.
To enable: echo 1 >  /proc/sys/kernel/nmi_watchdog
To disable: echo 0 >  /proc/sys/kernel/nmi_watchdog

It can also achieved using the sysctl parameter kernel.nmi_watchdog

Link: http://lkml.kernel.org/r/1478034826-43888-4-git-send-email-babu.moger@oracle.comSigned-off-by: NBabu Moger <babu.moger@oracle.com>
Acked-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Josh Hunt <johunt@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Separate hardlockup code from watchdog.c and move it to watchdog_hld.c.
It is mostly straight forward.  Remove everything inside
CONFIG_HARDLOCKUP_DETECTORS.  This code will go to file watchdog_hld.c.
Also update the makefile accordigly.

Link: http://lkml.kernel.org/r/1478034826-43888-3-git-send-email-babu.moger@oracle.comSigned-off-by: NBabu Moger <babu.moger@oracle.com>
Acked-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Josh Hunt <johunt@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "Clean up watchdog handlers", v2.

This is an attempt to cleanup watchdog handlers.  Right now,
kernel/watchdog.c implements both softlockup and hardlockup detectors.
Softlockup code is generic.  Hardlockup code is arch specific.  Some
architectures don't use hardlockup detectors.  They use their own
watchdog detectors.  To make both these combination work, we have
numerous #ifdefs in kernel/watchdog.c.

We are trying here to make these handlers independent of each other.
Also provide an interface for architectures to implement their own
handlers.  watchdog_nmi_enable and watchdog_nmi_disable will be defined
as weak such that architectures can override its definitions.

Thanks to Don Zickus for his suggestions.
Here are our previous discussions
http://www.spinics.net/lists/sparclinux/msg16543.html
http://www.spinics.net/lists/sparclinux/msg16441.html

This patch (of 3):

Move shared macros and definitions to nmi.h so that watchdog.c, new file
watchdog_hld.c or any other architecture specific handler can use those
definitions.

Link: http://lkml.kernel.org/r/1478034826-43888-2-git-send-email-babu.moger@oracle.comSigned-off-by: NBabu Moger <babu.moger@oracle.com>
Acked-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Josh Hunt <johunt@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Ajdust spelling to more common "mandatory".  Variant "mandidory" is
certainly wrong.

Link: http://lkml.kernel.org/r/20161011073003.GA19476@amdSigned-off-by: NPavel Machek <pavel@ucw.cz>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This cast is no longer needed.

Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Intel Linux Wireless <linuxwifi@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The OpenRISC compiler (so far) fails to optimize away a large portion of
code containing a reference to posix_timer_event in alarmtimer.c when
CONFIG_POSIX_TIMERS is unset.  Let's give it a direct clue to let the
build succeed.

This fixes
[linux-next:master 6682/7183] alarmtimer.c:undefined reference to `posix_timer_event'
reported by kbuild test robot.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch fixes below warnings:

  WARNING: Missing a blank line after declarations
  WARNING: Block comments use a trailing */ on a separate line
  ERROR: spaces required around that '=' (ctx:WxV)

Above warnings were reported by checkpatch.pl

Link: http://lkml.kernel.org/r/1478604980-18062-1-git-send-email-p.shailesh@samsung.comSigned-off-by: NShailesh Pandey <p.shailesh@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When LONG_MIN is passed to msgrcv, one would expect to recieve any
message.  But convert_mode does *msgtyp = -*msgtyp and -LONG_MIN is
undefined.  In particular, with my gcc -LONG_MIN produces -LONG_MIN
again.

So handle this case properly by assigning LONG_MAX to *msgtyp if
LONG_MIN was specified as msgtyp to msgrcv.

This code:
  long msg[] = { 100, 200 };
  int m = msgget(IPC_PRIVATE, IPC_CREAT | 0644);
  msgsnd(m, &msg, sizeof(msg), 0);
  msgrcv(m, &msg, sizeof(msg), LONG_MIN, 0);

produces currently nothing:

  msgget(IPC_PRIVATE, IPC_CREAT|0644)     = 65538
  msgsnd(65538, {100, "\310\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16, 0) = 0
  msgrcv(65538, ...

Except a UBSAN warning:

  UBSAN: Undefined behaviour in ipc/msg.c:745:13
  negation of -9223372036854775808 cannot be represented in type 'long int':

With the patch, I see what I expect:

  msgget(IPC_PRIVATE, IPC_CREAT|0644)     = 0
  msgsnd(0, {100, "\310\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16, 0) = 0
  msgrcv(0, {100, "\310\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16, -9223372036854775808, 0) = 16

Link: http://lkml.kernel.org/r/20161024082633.10148-1-jslaby@suse.czSigned-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Choosing the appropriate compression option when using an embedded
initramfs can result in significant size differences in the resulting
data.

This is caused by avoiding double compression of the initramfs contents.
For example on my tests, choosing CONFIG_INITRAMFS_COMPRESSION_NONE when
compressing the kernel using XZ) results in up to 500KiB differences
(9MiB to 8.5MiB) in the kernel size as the dictionary will not get
polluted with uncomprensible data and may reuse kernel data too.

Despite embedding an uncompressed initramfs, a user may want to allow
for a compressed extra initramfs to be passed using the rd system, for
example to boot a recovery system.  9ba4bcb6 ("initramfs: read
CONFIG_RD_ variables for initramfs compression") broke that behavior by
making the choice based on CONFIG_RD_* instead of adding
CONFIG_INITRAMFS_COMPRESSION_LZ4.  Saddly, CONFIG_RD_* is also used to
choose the supported RD compression algorithms by the kernel and a user
may want to support more than one.

This patch also reverts commit 3e4e0f0a ("initramfs: remove
"compression mode" choice") restoring back the "compression mode" choice
and includes the CONFIG_INITRAMFS_COMPRESSION_LZ4 option which was never
added.

As a result the following options are added or readed affecting the embedded
initramfs compression:
  INITRAMFS_COMPRESSION_NONE Do no compression
  INITRAMFS_COMPRESSION_GZIP Compress using gzip
  INITRAMFS_COMPRESSION_BZIP2 Compress using bzip2
  INITRAMFS_COMPRESSION_LZMA Compress using lzma
  INITRAMFS_COMPRESSION_XZ Compress using xz
  INITRAMFS_COMPRESSION_LZO Compress using lzo
  INITRAMFS_COMPRESSION_LZ4 Compress using lz4

These depend on the corresponding CONFIG_RD_* option being set (except
NONE which has no dependencies).

This patch depends on the previous one (the previous version didn't) to
simplify the way in which the algorithm is chosen and keep backwards
compatibility with the behaviour introduced by 9ba4bcb6
("initramfs: read CONFIG_RD_ variables for initramfs compression").

Link: http://lkml.kernel.org/r/57EAD77B.7090607@klondike.esSigned-off-by: NFrancisco Blas Izquierdo Riera (klondike) <klondike@klondike.es>
Cc: P J P <ppandit@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move the current builtin initram compression algorithm selection from
the Makefile into the INITRAMFS_COMPRESSION variable.  This makes
deciding algorithm precedence easier and would allow for overrides if
new algorithms want to be tested.

Link: http://lkml.kernel.org/r/57EAD769.1090401@klondike.esSigned-off-by: NFrancisco Blas Izquierdo Riera (klondike) <klondike@klondike.es>
Cc: P J P <ppandit@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kdb_trap_printk allows to pass normal printk() messages to kdb via
vkdb_printk().  For example, it is used to get backtrace using the
classic show_stack(), see kdb_show_stack().

vkdb_printf() tries to avoid a potential infinite loop by disabling the
trap.  But this approach is racy, for example:

CPU1					CPU2

vkdb_printf()
  // assume that kdb_trap_printk == 0
  saved_trap_printk = kdb_trap_printk;
  kdb_trap_printk = 0;

					kdb_show_stack()
					  kdb_trap_printk++;

Problem1: Now, a nested printk() on CPU0 calls vkdb_printf()
	  even when it should have been disabled. It will not
	  cause a deadlock but...

   // using the outdated saved value: 0
   kdb_trap_printk = saved_trap_printk;

					  kdb_trap_printk--;

Problem2: Now, kdb_trap_printk == -1 and will stay like this.
   It means that all messages will get passed to kdb from
   now on.

This patch removes the racy saved_trap_printk handling.  Instead, the
recursion is prevented by a check for the locked CPU.

The solution is still kind of racy.  A non-related printk(), from
another process, might get trapped by vkdb_printf().  And the wanted
printk() might not get trapped because kdb_printf_cpu is assigned.  But
this problem existed even with the original code.

A proper solution would be to get_cpu() before setting kdb_trap_printk
and trap messages only from this CPU.  I am not sure if it is worth the
effort, though.

In fact, the race is very theoretical.  When kdb is running any of the
commands that use kdb_trap_printk there is a single active CPU and the
other CPUs should be in a holding pen inside kgdb_cpu_enter().

The only time this is violated is when there is a timeout waiting for
the other CPUs to report to the holding pen.

Finally, note that the situation is a bit schizophrenic.  vkdb_printf()
explicitly allows recursion but only from KDB code that calls
kdb_printf() directly.  On the other hand, the generic printk()
recursion is not allowed because it might cause an infinite loop.  This
is why we could not hide the decision inside vkdb_printf() easily.

Link: http://lkml.kernel.org/r/1480412276-16690-4-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kdb_printf_lock does not prevent other CPUs from entering the critical
section because it is ignored when KDB_STATE_PRINTF_LOCK is set.

The problematic situation might look like:

CPU0					CPU1

vkdb_printf()
  if (!KDB_STATE(PRINTF_LOCK))
    KDB_STATE_SET(PRINTF_LOCK);
    spin_lock_irqsave(&kdb_printf_lock, flags);

					vkdb_printf()
					  if (!KDB_STATE(PRINTF_LOCK))

BANG: The PRINTF_LOCK state is set and CPU1 is entering the critical
section without spinning on the lock.

The problem is that the code tries to implement locking using two state
variables that are not handled atomically.  Well, we need a custom
locking because we want to allow reentering the critical section on the
very same CPU.

Let's use solution from Petr Zijlstra that was proposed for a similar
scenario, see
https://lkml.kernel.org/r/20161018171513.734367391@infradead.org

This patch uses the same trick with cmpxchg().  The only difference is
that we want to handle only recursion from the same context and
therefore we disable interrupts.

In addition, KDB_STATE_PRINTF_LOCK is removed.  In fact, we are not able
to set it a non-racy way.

Link: http://lkml.kernel.org/r/1480412276-16690-3-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
Reviewed-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kdb_event state variable is only set but never checked in the kernel
code.

http://www.spinics.net/lists/kdb/msg01733.html suggests that this
variable affected WARN_CONSOLE_UNLOCKED() in the original
implementation.  But this check never went upstream.

The semantic is unclear and racy.  The value is updated after the
kdb_printf_lock is acquired and after it is released.  It should be
symmetric at minimum.  The value should be manipulated either inside or
outside the locked area.

Fortunately, it seems that the original function is gone and we could
simply remove the state variable.

Link: http://lkml.kernel.org/r/1480412276-16690-2-git-send-email-pmladek@suse.comSigned-off-by: NPetr Mladek <pmladek@suse.com>
Suggested-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We've got a delay loop waiting for secondary CPUs.  That loop uses
loops_per_jiffy.  However, loops_per_jiffy doesn't actually mean how
many tight loops make up a jiffy on all architectures.  It is quite
common to see things like this in the boot log:

  Calibrating delay loop (skipped), value calculated using timer
  frequency.. 48.00 BogoMIPS (lpj=24000)

In my case I was seeing lots of cases where other CPUs timed out
entering the debugger only to print their stack crawls shortly after the
kdb> prompt was written.

Elsewhere in kgdb we already use udelay(), so that should be safe enough
to use to implement our timeout.  We'll delay 1 ms for 1000 times, which
should give us a full second of delay (just like the old code wanted)
but allow us to notice that we're done every 1 ms.

[akpm@linux-foundation.org: simplifications, per Daniel]
Link: http://lkml.kernel.org/r/1477091361-2039-1-git-send-email-dianders@chromium.orgSigned-off-by: NDouglas Anderson <dianders@chromium.org>
Reviewed-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Brian Norris <briannorris@chromium.org>
Cc: <stable@vger.kernel.org>	[4.0+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is fragile that some definitions acquired via transitive
dependencies, as shown in below:

atomic_*        (<linux/atomic.h>)
ENOMEM/EN*      (<linux/errno.h>)
EXPORT_SYMBOL   (<linux/export.h>)
device_initcall (<linux/init.h>)
preempt_*       (<linux/preempt.h>)

Include them to prevent possible issues.

Link: http://lkml.kernel.org/r/1481163221-40170-1-git-send-email-wangkefeng.wang@huawei.comSigned-off-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Suggested-by: NMark Rutland <mark.rutland@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documenation/ubsan.txt was moved to Documentation/dev-tools/ubsan.rst,
this fixes the reference.

Link: http://lkml.kernel.org/r/1476698152-29340-3-git-send-email-andreas.platschek@opentech.atSigned-off-by: NAndreas Platschek <andreas.platschek@opentech.at>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation on development tools was moved to Documentation/devl-tools
and sphinxified (renamed from .txt to .rst).

References in lib/Kconfig.debug need to be updated to the new location.

Link: http://lkml.kernel.org/r/1476698152-29340-2-git-send-email-andreas.platschek@opentech.atSigned-off-by: NAndreas Platschek <andreas.platschek@opentech.at>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Smatch complains that we started using the array offset before we
checked that it was valid.

Fixes: 017c59c0 ('relay: Use per CPU constructs for the relay channel buffer pointers')
Link: http://lkml.kernel.org/r/20161013084947.GC16198@mwandaSigned-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the driver code so that we do bulk updates of the page reference
count instead of just incrementing it by one reference at a time.  The
advantage to doing this is that we cut down on atomic operations and
this in turn should give us a slight improvement in cycles per packet.
In addition if we eventually move this over to using build_skb the gains
will be more noticeable.

Link: http://lkml.kernel.org/r/20161110113616.76501.17072.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Helge Deller <deller@gmx.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The ARM architecture provides a mechanism for deferring cache line
invalidation in the case of map/unmap.  This patch makes use of this
mechanism to avoid unnecessary synchronization.

A secondary effect of this change is that the portion of the page that
has been synchronized for use by the CPU should be writable and could be
passed up the stack (at least on ARM).

The last bit that occurred to me is that on architectures where the
sync_for_cpu call invalidates cache lines we were prefetching and then
invalidating the first 128 bytes of the packet.  To avoid that I have
moved the sync up to before we perform the prefetch and allocate the
skbuff so that we can actually make use of it.

Link: http://lkml.kernel.org/r/20161110113611.76501.98897.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Helge Deller <deller@gmx.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a function that allows us to batch free a page that has multiple
references outstanding.  Specifically this function can be used to drop
a page being used in the page frag alloc cache.  With this drivers can
make use of functionality similar to the page frag alloc cache without
having to do any workarounds for the fact that there is no function that
frees multiple references.

Link: http://lkml.kernel.org/r/20161110113606.76501.70752.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Helge Deller <deller@gmx.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add support for mapping and unmapping a page with attributes.

The primary use for this is currently to allow for us to pass the
DMA_ATTR_SKIP_CPU_SYNC attribute when mapping and unmapping a page.  On
some architectures such as ARM the synchronization has significant
overhead and if we are already taking care of the sync_for_cpu and
sync_for_device from the driver there isn't much need to handle this in
the map/unmap calls as well.

Link: http://lkml.kernel.org/r/20161110113601.76501.46095.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113555.76501.52536.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113550.76501.73060.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113544.76501.40008.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113539.76501.6539.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113534.76501.86492.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113529.76501.44762.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113524.76501.87966.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113518.76501.52225.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Reviewed-by: NTobias Klauser <tklauser@distanz.ch>
Cc: Ley Foon Tan <lftan@altera.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113513.76501.32321.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113508.76501.77583.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113503.76501.80809.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: James Hogan <james.hogan@imgtec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
later via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113457.76501.77603.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
later via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113452.76501.45864.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The use of DMA_ATTR_SKIP_CPU_SYNC was not consistent across all of the
DMA APIs in the arch/arm folder.  This change is meant to correct that
so that we get consistent behavior.

Link: http://lkml.kernel.org/r/20161110113447.76501.93160.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
later via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113442.76501.7673.stgit@ahduyck-blue-test.jf.intel.comSigned-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: NMark Salter <msalter@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>