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linux-uconsole/arch/ia64/include/asm
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Peter Zijlstra a03a2426ea arch: Introduce smp_load_acquire(), smp_store_release() 
A number of situations currently require the heavyweight smp_mb(),
even though there is no need to order prior stores against later
loads.  Many architectures have much cheaper ways to handle these
situations, but the Linux kernel currently has no portable way
to make use of them.

This commit therefore supplies smp_load_acquire() and
smp_store_release() to remedy this situation.  The new
smp_load_acquire() primitive orders the specified load against
any subsequent reads or writes, while the new smp_store_release()
primitive orders the specifed store against any prior reads or
writes.  These primitives allow array-based circular FIFOs to be
implemented without an smp_mb(), and also allow a theoretical
hole in rcu_assign_pointer() to be closed at no additional
expense on most architectures.

In addition, the RCU experience transitioning from explicit
smp_read_barrier_depends() and smp_wmb() to rcu_dereference()
and rcu_assign_pointer(), respectively resulted in substantial
improvements in readability.  It therefore seems likely that
replacing other explicit barriers with smp_load_acquire() and
smp_store_release() will provide similar benefits.  It appears
that roughly half of the explicit barriers in core kernel code
might be so replaced.

[Changelog by PaulMck]
(cherry picked from commit 47933ad41a)

Reviewed-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Victor Kaplansky <VICTORK@il.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20131213150640.908486364@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-07 16:42:29 -07:00
..
native ia64/pv_ops: paravirtualize gate.S. 2009-03-26 11:01:46 -07:00
sn Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
uv Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
xen cputime: Generic on-demand virtual cputime accounting 2013-01-27 19:23:27 +01:00
acpi-ext.h ACPI: remove private acpica headers from driver files 2008-12-31 01:15:22 -05:00
acpi.h ACPICA: Update compilation environment settings. 2013-01-10 12:36:17 +01:00
agp.h agp: kill phys_to_gart() and gart_to_phys() 2009-08-03 09:05:00 +01:00
asm-offsets.h kbuild: move asm-offsets.h to include/generated 2009-12-12 13:08:14 +01:00
asmmacro.h Rename .data..patch.XXX to .data..patch.XXX. 2010-03-03 11:25:59 +01:00
atomic.h [IA64] Redefine ATOMIC_INIT and ATOMIC64_INIT to drop the casts 2012-07-26 10:55:26 -07:00
barrier.h arch: Introduce smp_load_acquire(), smp_store_release() 2014-10-07 16:42:29 -07:00
bitops.h asm-generic: add another generic ext2 atomic bitops 2011-07-26 16:49:46 -07:00
bug.h
bugs.h
cache.h Rename .data.read_mostly to .data..read_mostly. 2010-03-03 11:26:00 +01:00
cacheflush.h block: add helpers to run flush_dcache_page() against a bio and a request's pages 2009-11-26 09:16:19 +01:00
checksum.h
clocksource.h clocksource: Change __ARCH_HAS_CLOCKSOURCE_DATA to a CONFIG option 2011-07-21 13:34:05 -07:00
cpu.h
cputime.h cputime: Generic on-demand virtual cputime accounting 2013-01-27 19:23:27 +01:00
current.h
cyclone.h
delay.h
device.h driver core / ACPI: Move ACPI support to core device and driver types 2012-11-15 00:28:00 +01:00
div64.h
dma-mapping.h ia64: dma_debug: add debug_dma_mapping_error support 2012-11-28 15:28:58 +01:00
dma.h
dmi.h include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
elf.h default SET_PERSONALITY() in linux/elf.h 2013-02-26 02:46:08 -05:00
emergency-restart.h
esi.h
fb.h
fpswa.h
ftrace.h [IA64] sanity in #include files. Move fnptr to types.h 2010-01-06 15:52:35 -08:00
futex.h Wrong asm register contraints in the futex implementation 2013-03-19 16:14:53 -07:00
gcc_intrin.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
gpio.h gpiolib/arches: Centralise bolierplate asm/gpio.h 2012-05-11 18:00:14 -06:00
hardirq.h [IA64] Move local_softirq_pending() definition 2010-10-19 13:31:11 +02:00
hpsim.h hpsim, initialize chip for assigned irqs 2012-03-08 12:26:30 -08:00
hugetlb.h mm/hugetlb: add more arch-defined huge_pte functions 2013-04-29 15:54:33 -07:00
hw_irq.h ia64: Remove redundant declaration of irq_desc[] 2011-03-29 14:48:05 +02:00
idle.h [IA64] xen_domu_defconfig: fix build issues/warnings 2009-05-05 11:43:13 -07:00
intrinsics.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
io.h /dev/mem: use phys_addr_t for physical addresses 2012-10-24 15:32:50 -07:00
iommu.h iommu: Remove group_mf 2012-06-25 13:48:30 +02:00
iommu_table.h ia64, iommu: Add a dummy iommu_table.h file in IA64. 2010-10-08 13:11:11 -07:00
iosapic.h IA64: drivers: remove __dev* attributes. 2013-01-03 15:57:13 -08:00
irq.h ia64: move nr-irqs.h to include/generated 2009-12-12 13:08:14 +01:00
irq_regs.h
irq_remapping.h iommu: rename intr_remapping.[ch] to irq_remapping.[ch] 2012-05-07 14:35:00 +02:00
irqflags.h [IA64] Fix include dependency in asm/irqflags.h 2013-06-17 13:39:52 -07:00
Kbuild tracing,x86: Add a TSC trace_clock 2012-11-13 15:48:27 -05:00
kdebug.h
kexec.h Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
kmap_types.h kmap_types: make most arches use generic header file 2009-06-16 19:47:51 -07:00
kprobes.h [IA64] sanity in #include files. Move fnptr to types.h 2010-01-06 15:52:35 -08:00
kregs.h
kvm_host.h KVM: IA64: Carry non-ia64 changes into ia64 2013-04-26 20:27:27 +02:00
libata-portmap.h
linkage.h consolidate cond_syscall and SYSCALL_ALIAS declarations 2013-03-03 22:55:19 -05:00
local.h
local64.h arch: Implement local64_t 2010-06-09 11:12:36 +02:00
machvec.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_dig.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_dig_vtd.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_hpsim.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_hpzx1.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_hpzx1_swiotlb.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_init.h [IA64] SN specific version of dma_get_required_mask() 2009-01-15 10:42:16 -08:00
machvec_sn2.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_uv.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
machvec_xen.h [IA64] Rename platform_name to ia64_platform_name 2012-07-25 11:47:16 -07:00
mc146818rtc.h
mca.h Fix initialization of CMCI/CMCP interrupts 2013-04-02 09:37:06 -07:00
mca_asm.h Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
meminit.h ia64: don't alias VMALLOC_END to vmalloc_end 2009-10-02 13:28:55 +09:00
mman.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
mmu.h
mmu_context.h cpumask: use mm_cpumask() wrapper: ia64 2009-03-16 14:12:48 +10:30
mmzone.h [IA64] removing redundant ifdef 2010-05-18 14:45:52 -07:00
module.h Make most arch asm/module.h files use asm-generic/module.h 2012-09-28 14:31:03 +09:30
msidef.h ia64: Move the macro definitions related to MSI to one header file. 2009-03-24 11:03:12 +02:00
mutex.h
nodedata.h
numa.h Fix build error for numa_clear_node() under IA64 2013-04-02 09:39:48 -07:00
page.h Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
pal.h Fix common misspellings 2011-03-31 11:26:23 -03:00
param.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
paravirt.h static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() 2012-02-24 10:05:59 +01:00
paravirt_patch.h ia64/pv_op/binarypatch: add helper functions to support binary patching for paravirt_ops. 2009-03-26 11:02:31 -07:00
paravirt_privop.h [IA64] fix allmodconfig compilation breakage. 2009-04-20 09:46:29 -07:00
parport.h IA64: drivers: remove __dev* attributes. 2013-01-03 15:57:13 -08:00
patch.h
pci.h Disintegrate and delete asm/system.h 2012-03-28 15:58:21 -07:00
percpu.h Merge branch 'for-35' of git://repo.or.cz/linux-kbuild 2010-06-01 08:55:52 -07:00
perfmon.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
pgalloc.h mm: Pass virtual address to [__]p{te,ud,md}_free_tlb() 2009-07-27 12:10:38 -07:00
pgtable.h Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
processor.h ia64: switch to generic kernel_thread()/kernel_execve() 2012-10-19 14:28:09 -04:00
ptrace.h new helper: current_user_stack_pointer() 2012-12-19 18:07:39 -05:00
pvclock-abi.h
rwsem.h rwsem: Move duplicate function prototypes to linux/rwsem.h 2011-01-27 12:30:39 +01:00
sal.h Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
scatterlist.h remove needless ISA_DMA_THRESHOLD 2010-08-07 18:15:50 +02:00
sections.h
segment.h
serial.h
shmparam.h
siginfo.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
signal.h consolidate kernel-side struct sigaction declarations 2013-02-03 15:09:22 -05:00
smp.h IA64: drivers: remove __dev* attributes. 2013-01-03 15:57:13 -08:00
sparsemem.h
spinlock.h Disintegrate asm/system.h for IA64 2012-03-28 18:30:02 +01:00
spinlock_types.h locking: Convert raw_rwlock to arch_rwlock 2009-12-14 23:55:32 +01:00
string.h
swiotlb.h swiotlb: Remove duplicate swiotlb_force extern declarations 2009-11-15 09:03:10 +01:00
switch_to.h cputime: Consolidate vtime handling on context switch 2012-08-20 13:05:28 +02:00
sync_bitops.h
syscall.h [IA64] Remove COMPAT_IA32 support 2010-02-08 10:42:17 -08:00
termios.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
thread_info.h arch: Consolidate tsk_is_polling() 2013-04-08 17:39:22 +02:00
timex.h ia64/pv_ops/pv_time_ops: add sched_clock hook. 2009-03-26 10:50:42 -07:00
tlb.h arch, mm: Remove tlb_fast_mode() 2013-06-06 10:07:26 +09:00
tlbflush.h
topology.h sched/numa: Rewrite the CONFIG_NUMA sched domain support 2012-05-09 15:00:55 +02:00
types.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
uaccess.h
unaligned.h
uncached.h
unistd.h consolidate cond_syscall and SYSCALL_ALIAS declarations 2013-03-03 22:55:19 -05:00
unwind.h
user.h
ustack.h UAPI: (Scripted) Disintegrate arch/ia64/include/asm 2012-10-09 09:47:00 +01:00
vga.h
xor.h