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Remap percpu allocator has subtle bug when combined with page
attribute changing. Remap percpu allocator aliases PMD pages for the
first chunk and as pageattr doesn't know about the alias it ends up
updating page attributes of the original mapping thus leaving the
alises in inconsistent state which might lead to subtle data
corruption. Please read the following threads for more information:
http://thread.gmane.org/gmane.linux.kernel/835783
The following is the proposed fix which teaches pageattr about percpu
aliases.
http://thread.gmane.org/gmane.linux.kernel/837157
However, the above changes are deemed too pervasive for upstream
inclusion for 2.6.30 release, so this patch essentially disables
the remap allocator for the time being.
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <4A1A0A27.4050301@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: clean up
those code pcpu_need_numa(), should be removed.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: David Miller <davem@davemloft.net>
LKML-Reference: <49D31770.9090502@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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setup_percpu_remap() is for NUMA machines yet it bailed out with
-EINVAL if pcpu_need_numa(). Fix the inverted condition.
This problem was reported by David Miller and verified by Yinhai Lu.
Reported-by: David Miller <davem@davemloft.net>
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <49D30469.8020006@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: code reorganization
Separate out embedding first chunk setup helper from x86 embedding
first chunk allocator and put it in mm/percpu.c. This will be used by
the default percpu first chunk allocator and possibly by other archs.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: cleanup, more flexibility for first chunk init
Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto.
This restriction stemmed from implementation detail and made things a
bit less intuitive. This patch allows @dyn_size to be specified
regardless of @unit_size and swaps the positions of @dyn_size and
@unit_size so that the parameter order makes more sense (static,
reserved and dyn sizes followed by enclosing unit_size).
While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: fix relocation overflow during module load
x86_64 uses 32bit relocations for symbol access and static percpu
symbols whether in core or modules must be inside 2GB of the percpu
segement base which the dynamic percpu allocator doesn't guarantee.
This patch makes x86_64 reserve PERCPU_MODULE_RESERVE bytes in the
first chunk so that module percpu areas are always allocated from the
first chunk which is always inside the relocatable range.
This problem exists for any percpu allocator but is easily triggered
when using the embedding allocator because the second chunk is located
beyond 2GB on it.
This patch also changes the meaning of PERCPU_DYNAMIC_RESERVE such
that it only indicates the size of the area to reserve for dynamic
allocation as static and dynamic areas can be separate. New
PERCPU_DYNAMIC_RESERVED is increased by 4k for both 32 and 64bits as
the reserved area separation eats away some allocatable space and
having slightly more headroom (currently between 4 and 8k after
minimal boot sans module area) makes sense for common case
performance.
x86_32 can address anywhere from anywhere and doesn't need reserving.
Mike Galbraith first reported the problem first and bisected it to the
embedding percpu allocator commit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Mike Galbraith <efault@gmx.de>
Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
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variables
Impact: add reserved allocation functionality and use it for module
percpu variables
This patch implements reserved allocation from the first chunk. When
setting up the first chunk, arch can ask to set aside certain number
of bytes right after the core static area which is available only
through a separate reserved allocator. This will be used primarily
for module static percpu variables on architectures with limited
relocation range to ensure that the module perpcu symbols are inside
the relocatable range.
If reserved area is requested, the first chunk becomes reserved and
isn't available for regular allocation. If the first chunk also
includes piggy-back dynamic allocation area, a separate chunk mapping
the same region is created to serve dynamic allocation. The first one
is called static first chunk and the second dynamic first chunk.
Although they share the page map, their different area map
initializations guarantee they serve disjoint areas according to their
purposes.
If arch doesn't setup reserved area, reserved allocation is handled
like any other allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: reduce unnecessary memory usage on certain configurations
Embedding percpu allocator allocates unit_size *
smp_num_possible_cpus() bytes consecutively and use it for the first
chunk. However, if the static area is small, this can result in
excessive prellocated free space in the first chunk due to
PCPU_MIN_UNIT_SIZE restriction.
This patch makes embedding percpu allocator preallocate only what's
necessary as described by PERPCU_DYNAMIC_RESERVE and return the
leftover to the bootmem allocator.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: argument semantic cleanup
In pcpu_setup_first_chunk(), zero @unit_size and @dyn_size meant
auto-sizing. It's okay for @unit_size as 0 doesn't make sense but 0
dynamic reserve size is valid. Alos, if arch @dyn_size is calculated
from other parameters, it might end up passing in 0 @dyn_size and
malfunction when the size is automatically adjusted.
This patch makes both @unit_size and @dyn_size ssize_t and use -1 for
auto sizing.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Recent changes in setup_percpu.c made a now meaningless DBG()
statement fail to compile and introduced a
comparison-of-different-types warning. Fix them.
Compile failure is reported by Ingo Molnar.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
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Impact: add better first percpu allocation for NUMA
On NUMA, embedding allocator can't be used as different units can't be
made to fall in the correct NUMA nodes. To use large page mapping,
each unit needs to be remapped. However, percpu areas are usually
much smaller than large page size and unused space hurts a lot as the
number of cpus grow. This allocator remaps large pages for each chunk
but gives back unused part to the bootmem allocator making the large
pages mapped twice.
This adds slightly to the TLB pressure but is much better than using
4k mappings while still being NUMA-friendly.
Ingo suggested that this would be the correct approach for NUMA.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
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Impact: add better first percpu allocation for !NUMA
On !NUMA, we can simply allocate contiguous memory and use it for the
first chunk without mapping it into vmalloc area. As the memory area
is covered by the large page physical memory mapping, it allows the
dynamic perpcu allocator to not add any TLB overhead for the static
percpu area and whatever falls into the first chunk and the
implementation is very simple too.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: modularize percpu first chunk allocation
x86 is gonna have a few different strategies for the first chunk
allocation. Modularize it by separating out the current allocation
mechanism into pcpu_alloc_bootmem() and setup_pcpu_4k().
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: more latitude for first percpu chunk allocation
The first percpu chunk serves the kernel static percpu area and may or
may not contain extra room for further dynamic allocation.
Initialization of the first chunk needs to be done before normal
memory allocation service is up, so it has its own init path -
pcpu_setup_static().
It seems archs need more latitude while initializing the first chunk
for example to take advantage of large page mapping. This patch makes
the following changes to allow this.
* Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space
to reserve in the first chunk for further dynamic allocation.
* Rename pcpu_setup_static() to pcpu_setup_first_chunk().
* Make pcpu_setup_first_chunk() much more flexible by fetching page
pointer by callback and adding optional @unit_size, @free_size and
@base_addr arguments which allow archs to selectively part of chunk
initialization to their likings.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: minor change to populate_extra_pte() and addition of pmd flavor
Update populate_extra_pte() to return pointer to the pte_t for the
specified address and add populate_extra_pmd() which only populates
till the pmd and returns pointer to the pmd entry for the address.
For 64bit, pud/pmd/pte fill functions are separated out from
set_pte_vaddr[_pud]() and used for set_pte_vaddr[_pud]() and
populate_extra_{pte|pmd}().
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: use new dynamic allocator, unified access to static/dynamic
percpu memory
Convert to the new dynamic percpu allocator.
* implement populate_extra_pte() for both 32 and 64
* update setup_per_cpu_areas() to use pcpu_setup_static()
* define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr()
* define config HAVE_DYNAMIC_PER_CPU_AREA
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: stack protector for x86_32
Implement stack protector for x86_32. GDT entry 28 is used for it.
It's set to point to stack_canary-20 and have the length of 24 bytes.
CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs
to the stack canary segment on entry. As %gs is otherwise unused by
the kernel, the canary can be anywhere. It's defined as a percpu
variable.
x86_32 exception handlers take register frame on stack directly as
struct pt_regs. With -fstack-protector turned on, gcc copies the
whole structure after the stack canary and (of course) doesn't copy
back on return thus losing all changed. For now, -fno-stack-protector
is added to all files which contain those functions. We definitely
need something better.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup, prepare for xen boot fix.
Xen needs to call this function very early to setup the GDT and
per-cpu segments. Remove the call to smp_processor_id() and just
pass in the cpu number.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: cosmetic cleanup
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: build fix
x86_cpu_to_apicid and x86_bios_cpu_apicid aren't defined for voyage.
Earlier patch forgot to conditionalize early percpu clearing. Fix it.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: sync 32 and 64-bit code
Merge load_gs_base() into switch_to_new_gdt(). Load the GDT and
per-cpu state for the boot cpu when its new area is set up.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: cleanup
Rename init_gdt() to setup_percpu_segment(), and move it to
setup_percpu.c.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: standardize all x86 platforms on same setup code
With the preceding changes, Voyager can use the same per-cpu setup
code as all the other x86 platforms.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: minor cleanup
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: Small cleanup
Define BOOT_PERCPU_OFFSET and use it for this_cpu_offset and
__per_cpu_offset initializers.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: Minor build optimization
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: Code movement
Move the variable definitions to apic.c. Ifdef the copying of
the two early per-cpu variables, since Voyager doesn't use them.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: cleanup
The way the code is written, align is always PAGE_SIZE. Simplify
the code by removing the align variable.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: Code movement, no functional change.
Move setup_cpu_local_masks() to kernel/cpu/common.c, where the
masks are defined.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: Code movement, no functional change.
Move the 64-bit NUMA code from setup_percpu.c to numa_64.c
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: minor optimization
Eliminates the need for two loops over possible cpus.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Impact: x86_64 percpu area layout change, irq_stack now at the beginning
Now that the PDA is empty except for the stack canary, it can be removed.
The irqstack is moved to the start of the per-cpu section. If the stack
protector is enabled, the canary overlaps the bottom 48 bytes of the irqstack.
tj: * updated subject
* dropped asm relocation of irq_stack_ptr
* updated comments a bit
* rebased on top of stack canary changes
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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tj: * s/nodenumber/node_number/
* removed now unused pda variable from pda_init()
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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tj: moved cpu_number definition out of CONFIG_HAVE_SETUP_PER_CPU_AREA
for voyager.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Move the irqstackptr variable from the PDA to per-cpu. Make the
stacks themselves per-cpu, removing some specific allocation code.
Add a seperate flag (is_boot_cpu) to simplify the per-cpu boot
adjustments.
tj: * sprinkle some underbars around.
* irq_stack_ptr is not used till traps_init(), no reason to
initialize it early. On SMP, just leaving it NULL till proper
initialization in setup_per_cpu_areas() works. Dropped
is_boot_cpu and early irq_stack_ptr initialization.
* do DECLARE/DEFINE_PER_CPU(char[IRQ_STACK_SIZE], irq_stack)
instead of (char, irq_stack[IRQ_STACK_SIZE]).
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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EXPORT_PER_CPU_SYMBOL() got misplaced during merge leading to build
failure. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
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[ Based on original patch from Christoph Lameter and Mike Travis. ]
As pda is now allocated in percpu area, it can easily be made a proper
percpu variable. Make it so by defining per cpu symbol from linker
script and declaring it in C code for SMP and simply defining it for
UP. This change cleans up code and brings SMP and UP closer a bit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Now that pda is allocated as part of percpu, percpu doesn't need to be
accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP
one. Other than the segment register, operand size and the base of
percpu symbols, they behave identical now.
This patch replaces now unnecessary pda->data_offset with a dummy
field which is necessary to keep stack_canary at its place. This
patch also moves per_cpu_offset initialization out of init_gdt() into
setup_per_cpu_areas(). Note that this change also necessitates
explicit per_cpu_offset initializations in voyager_smp.c.
With this change, x86_OP_percpu()'s are as efficient on x86_64 as on
x86_32 and also x86_64 can use assembly PER_CPU macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Based on original patch from Christoph Lameter and Mike Travis. ]
Currently pdas and percpu areas are allocated separately. %gs points
to local pda and percpu area can be reached using pda->data_offset.
This patch folds pda into percpu area.
Due to strange gcc requirement, pda needs to be at the beginning of
the percpu area so that pda->stack_canary is at %gs:40. To achieve
this, a new percpu output section macro - PERCPU_VADDR_PREALLOC() - is
added and used to reserve pda sized chunk at the start of the percpu
area.
After this change, for boot cpu, %gs first points to pda in the
data.init area and later during setup_per_cpu_areas() gets updated to
point to the actual pda. This means that setup_per_cpu_areas() need
to reload %gs for CPU0 while clearing pda area for other cpus as cpu0
already has modified it when control reaches setup_per_cpu_areas().
This patch also removes now unnecessary get_local_pda() and its call
sites.
A lot of this patch is taken from Mike Travis' "x86_64: Fold pda into
per cpu area" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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_cpu_pda array first uses statically allocated storage in data.init
and then switches to allocated bootmem to conserve space. However,
after folding pda area into percpu area, _cpu_pda array will be
removed completely. Drop the reallocation part to simplify the code
for soon-to-follow changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Based on original patch from Christoph Lameter and Mike Travis. ]
This patch makes percpu symbols zerobased on x86_64 SMP by adding
PERCPU_VADDR() to vmlinux.lds.h which helps setting explicit vaddr on
the percpu output section and using it in vmlinux_64.lds.S. A new
PHDR is added as existing ones cannot contain sections near address
zero. PERCPU_VADDR() also adds a new symbol __per_cpu_load which
always points to the vaddr of the loaded percpu data.init region.
The following adjustments have been made to accomodate the address
change.
* code to locate percpu gdt_page in head_64.S is updated to add the
load address to the gdt_page offset.
* __per_cpu_load is used in places where access to the init data area
is necessary.
* pda->data_offset is initialized soon after C code is entered as zero
value doesn't work anymore.
This patch is mostly taken from Mike Travis' "x86_64: Base percpu
variables at zero" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Based on original patch from Christoph Lameter and Mike Travis. ]
* Ruggedize some calls in setup_percpu.c to prevent mishaps
in early calls, particularly for non-critical functions.
* Cleanup DEBUG_PER_CPU_MAPS usages and some comments.
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (36 commits)
x86: fix section mismatch warnings in mcheck/mce_amd_64.c
x86: offer frame pointers in all build modes
x86: remove duplicated #include's
x86: k8 numa register active regions later
x86: update Alan Cox's email addresses
x86: rename all fields of mpc_table mpc_X to X
x86: rename all fields of mpc_oemtable oem_X to X
x86: rename all fields of mpc_bus mpc_X to X
x86: rename all fields of mpc_cpu mpc_X to X
x86: rename all fields of mpc_intsrc mpc_X to X
x86: rename all fields of mpc_lintsrc mpc_X to X
x86: rename all fields of mpc_iopic mpc_X to X
x86: irqinit_64.c init_ISA_irqs should be static
Documentation/x86/boot.txt: payload length was changed to payload_length
x86: setup_percpu.c fix style problems
x86: irqinit_64.c fix style problems
x86: irqinit_32.c fix style problems
x86: i8259.c fix style problems
x86: irq_32.c fix style problems
x86: ioport.c fix style problems
...
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x86/urgent
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Impact: cleanup
Fix:
WARNING: Use #include <linux/smp.h> instead of <asm/smp.h>
WARNING: Use #include <linux/percpu.h> instead of <asm/percpu.h>
WARNING: Use #include <linux/topology.h> instead of <asm/topology.h>
WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
ERROR: spaces required around that '?' (ctx:VxW)
ERROR: spaces required around that ':' (ctx:VxV)
total: 2 errors, 4 warnings
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: use new cpumask API to reduce memory and stack usage
Allocate the following local cpumasks based on the number of cpus that
are present. References will use new cpumask API. (Currently only
modified for x86_64, x86_32 continues to use the *_map variants.)
cpu_callin_mask
cpu_callout_mask
cpu_initialized_mask
cpu_sibling_setup_mask
Provide the following accessor functions:
struct cpumask *cpu_sibling_mask(int cpu)
struct cpumask *cpu_core_mask(int cpu)
Other changes are when setting or clearing the cpu online, possible
or present maps, use the accessor functions.
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
__alloc_bootmem and __alloc_bootmem_node do panic
for us in case of fail so no need for additional
checks here.
Also lets use pr_*() macros for printing.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-cpumask into merge-rr-cpumask
Conflicts:
arch/x86/kernel/io_apic.c
kernel/rcuclassic.c
kernel/sched.c
kernel/time/tick-sched.c
Signed-off-by: Mike Travis <travis@sgi.com>
[ mingo@elte.hu: backmerged typo fix for io_apic.c ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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{node,pcibus}_to_cpumask
Impact: New APIs
The old node_to_cpumask/node_to_pcibus returned a cpumask_t: these
return a pointer to a struct cpumask. Part of removing cpumasks from
the stack.
Also makes __pcibus_to_node take a const pointer.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
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