linux-stable.git/include/asm-generic, branch v4.4.16

locking/qspinlock: Fix spin_unlock_wait() some more

2016-07-27T16:47:29+00:00

commit 2c610022711675ee908b903d242f0b90e1db661f upstream.

While this prior commit:

  54cf809b9512 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()")

... fixes spin_is_locked() and spin_unlock_wait() for the usage
in ipc/sem and netfilter, it does not in fact work right for the
usage in task_work and futex.

So while the 2 locks crossed problem:

	spin_lock(A)		spin_lock(B)
	if (!spin_is_locked(B)) spin_unlock_wait(A)
	  foo()			foo();

... works with the smp_mb() injected by both spin_is_locked() and
spin_unlock_wait(), this is not sufficient for:

	flag = 1;
	smp_mb();		spin_lock()
	spin_unlock_wait()	if (!flag)
				  // add to lockless list
	// iterate lockless list

... because in this scenario, the store from spin_lock() can be delayed
past the load of flag, uncrossing the variables and loosing the
guarantee.

This patch reworks spin_is_locked() and spin_unlock_wait() to work in
both cases by exploiting the observation that while the lock byte
store can be delayed, the contender must have registered itself
visibly in other state contained in the word.

It also allows for architectures to override both functions, as PPC
and ARM64 have an additional issue for which we currently have no
generic solution.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Boqun Feng 
Cc: Davidlohr Bueso 
Cc: Giovanni Gherdovich 
Cc: Linus Torvalds 
Cc: Pan Xinhui 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Waiman Long 
Cc: Will Deacon 
Fixes: 54cf809b9512 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()")
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

SIGNAL: Move generic copy_siginfo() to signal.h

2016-06-01T19:15:54+00:00

commit ca9eb49aa9562eaadf3cea071ec7018ad6800425 upstream.

The generic copy_siginfo() is currently defined in
asm-generic/siginfo.h, after including uapi/asm-generic/siginfo.h which
defines the generic struct siginfo. However this makes it awkward for an
architecture to use it if it has to define its own struct siginfo (e.g.
MIPS and potentially IA64), since it means that asm-generic/siginfo.h
can only be included after defining the arch-specific siginfo, which may
be problematic if the arch-specific definition needs definitions from
uapi/asm-generic/siginfo.h.

It is possible to work around this by first including
uapi/asm-generic/siginfo.h to get the constants before defining the
arch-specific siginfo, and include asm-generic/siginfo.h after. However
uapi headers can't be included by other uapi headers, so that first
include has to be in an ifdef __kernel__, with the non __kernel__ case
including the non-UAPI header instead.

Instead of that mess, move the generic copy_siginfo() definition into
linux/signal.h, which allows an arch-specific uapi/asm/siginfo.h to
include asm-generic/siginfo.h and define the arch-specific siginfo, and
for the generic copy_siginfo() to see that arch-specific definition.

Signed-off-by: James Hogan 
Cc: Arnd Bergmann 
Cc: Ralf Baechle 
Cc: Petr Malat 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Christopher Ferris 
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12478/
Signed-off-by: Ralf Baechle 
Signed-off-by: Greg Kroah-Hartman

locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()

2016-06-01T19:15:53+00:00

commit 54cf809b9512be95f53ed4a5e3b631d1ac42f0fa upstream.

Similar to commits:

  51d7d5205d33 ("powerpc: Add smp_mb() to arch_spin_is_locked()")
  d86b8da04dfa ("arm64: spinlock: serialise spin_unlock_wait against concurrent lockers")

qspinlock suffers from the fact that the _Q_LOCKED_VAL store is
unordered inside the ACQUIRE of the lock.

And while this is not a problem for the regular mutual exclusive
critical section usage of spinlocks, it breaks creative locking like:

	spin_lock(A)			spin_lock(B)
	spin_unlock_wait(B)		if (!spin_is_locked(A))
	do_something()			  do_something()

In that both CPUs can end up running do_something at the same time,
because our _Q_LOCKED_VAL store can drop past the spin_unlock_wait()
spin_is_locked() loads (even on x86!!).

To avoid making the normal case slower, add smp_mb()s to the less used
spin_unlock_wait() / spin_is_locked() side of things to avoid this
problem.

Reported-and-tested-by: Davidlohr Bueso 
Reported-by: Giovanni Gherdovich 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic()

2016-05-04T21:48:43+00:00

commit fba7cd681b6155e2d93e7862fcd6f970336b83c3 upstream.

The recent decoupling of pagefault disable and preempt disable added an
explicit preempt_disable/enable() pair to the futex_atomic_cmpxchg_inatomic()
implementation in asm-generic/futex.h. But it forgot to add preempt_enable()
calls to the error handling code pathes, which results in a preemption count
imbalance.

This is observable on boot when the test for atomic_cmpxchg() is calling
futex_atomic_cmpxchg_inatomic() on a NULL pointer.

Add the missing preempt_enable() calls to the error handling code pathes.

[ tglx: Massaged changelog ]

Fixes: d9b9ff8c1889 ("sched/preempt, futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly")
Signed-off-by: Romain Perier 
Cc: linux-arch@vger.kernel.org
Cc: Thomas Petazzoni 
Cc: Arnd Bergmann 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1460640963-690-1-git-send-email-romain.perier@free-electrons.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

bitops: Do not default to __clear_bit() for __clear_bit_unlock()

2016-04-12T16:09:00+00:00

commit f75d48644c56a31731d17fa693c8175328957e1d upstream.

__clear_bit_unlock() is a special little snowflake. While it carries the
non-atomic '__' prefix, it is specifically documented to pair with
test_and_set_bit() and therefore should be 'somewhat' atomic.

Therefore the generic implementation of __clear_bit_unlock() cannot use
the fully non-atomic __clear_bit() as a default.

If an arch is able to do better; is must provide an implementation of
__clear_bit_unlock() itself.

Specifically, this came up as a result of hackbench livelock'ing in
slab_lock() on ARC with SMP + SLUB + !LLSC.

The issue was incorrect pairing of atomic ops.

 slab_lock() -> bit_spin_lock() -> test_and_set_bit()
 slab_unlock() -> __bit_spin_unlock() -> __clear_bit()

The non serializing __clear_bit() was getting "lost"

 80543b8e:	ld_s       r2,[r13,0] <--- (A) Finds PG_locked is set
 80543b90:	or         r3,r2,1    <--- (B) other core unlocks right here
 80543b94:	st_s       r3,[r13,0] <--- (C) sets PG_locked (overwrites unlock)

Fixes ARC STAR 9000817404 (and probably more).

Reported-by: Vineet Gupta 
Tested-by: Vineet Gupta 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Christoph Lameter 
Cc: David Rientjes 
Cc: Helge Deller 
Cc: James E.J. Bottomley 
Cc: Joonsoo Kim 
Cc: Linus Torvalds 
Cc: Noam Camus 
Cc: Paul E. McKenney 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20160309114054.GJ6356@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

cputime: Prevent 32bit overflow in time[val|spec]_to_cputime()

2016-03-03T23:07:16+00:00

commit 0f26922fe5dc5724b1adbbd54b21bad03590b4f3 upstream.

The datatype __kernel_time_t is u32 on 32bit platform, so its subject to
overflows in the timeval/timespec to cputime conversion.

Currently the following functions are affected:
1. setitimer()
2. timer_create/timer_settime()
3. sys_clock_nanosleep

This can happen on MIPS32 and ARM32 with "Full dynticks CPU time accounting"
enabled, which is required for CONFIG_NO_HZ_FULL.

Enforce u64 conversion to prevent the overflow.

Fixes: 31c1fc818715 ("ARM: Kconfig: allow full nohz CPU accounting")
Signed-off-by: zengtao 
Reviewed-by: Arnd Bergmann 
Cc: 
Link: http://lkml.kernel.org/r/1454384314-154784-1-git-send-email-prime.zeng@huawei.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

treewide: Remove old email address

2015-11-23T08:44:58+00:00

There were still a number of references to my old Red Hat email
address in the kernel source. Remove these while keeping the
Red Hat copyright notices intact.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

Merge tag 'for-4.4' of git://git.osdn.jp/gitroot/uclinux-h8/linux

2015-11-12T23:26:39+00:00

Pull h8300 updates from Yoshinori Sato:
 "Some bug fixes"

* tag 'for-4.4' of git://git.osdn.jp/gitroot/uclinux-h8/linux:
  h8300: enable CLKSRC_OF
  h8300: Don't set CROSS_COMPILE unconditionally
  asm-generic: {get,put}_user ptr argument evaluate only 1 time
  h8300: bit io fix
  h8300: zImage fix
  h8300: register address fix
  h8300: Fix alignment for .data
  h8300: unaligned divcr register support.

pci: remove pci_dma_supported

2015-11-11T00:32:11+00:00

Signed-off-by: Christoph Hellwig 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

asm-generic: {get,put}_user ptr argument evaluate only 1 time

2015-11-08T13:44:42+00:00

Current implemantation ptr argument evaluate 2 times.
It'll be an unexpected result.

Changes v5:
Remove unnecessary const.
Changes v4:
Temporary pointer type change to const void*
Changes v3:
Some build error fix.
Changes v2:
Argument x protect.

Signed-off-by: Yoshinori Sato