Impact: Reduce memory usage, use new API.
This is part of an effort to reduce structure sizes for machines
configured with large NR_CPUS. cpumask_t gets replaced by
cpumask_var_t, which is either struct cpumask[1] (small NR_CPUS) or
struct cpumask * (large NR_CPUS).
(Changes to powernow-k* by <travis>.)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Reduce future system panics due to cpumask operations using NR_CPUS
Insure that code does not look at bits >= nr_cpu_ids as when cpumasks are
allocated based on nr_cpu_ids, these extra bits will not be defined.
Also some other minor updates:
* change in to use cpu accessor function set_cpu_present() instead of
directly accessing cpu_present_map w/cpu_clear() [arch/x86/kernel/reboot.c]
* use cpumask_of() instead of &cpumask_of_cpu() [arch/x86/kernel/reboot.c]
* optimize some cpu_mask_to_apicid_and 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>
Impact: fix section mismatch warning
Commit b2bb855491 ("x86: Remove cpumask games
in x86/kernel/cpu/intel_cacheinfo.c") introduced get_cpu_leaves(), which
references __cpuinit cpuid4_cache_lookup().
Mark get_cpu_leaves() with a __cpuinit annotation.
Signed-off-by: Sergio Luis <sergio@larces.uece.br>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (241 commits)
sched, trace: update trace_sched_wakeup()
tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3
Revert "x86: disable X86_PTRACE_BTS"
ring-buffer: prevent false positive warning
ring-buffer: fix dangling commit race
ftrace: enable format arguments checking
x86, bts: memory accounting
x86, bts: add fork and exit handling
ftrace: introduce tracing_reset_online_cpus() helper
tracing: fix warnings in kernel/trace/trace_sched_switch.c
tracing: fix warning in kernel/trace/trace.c
tracing/ring-buffer: remove unused ring_buffer size
trace: fix task state printout
ftrace: add not to regex on filtering functions
trace: better use of stack_trace_enabled for boot up code
trace: add a way to enable or disable the stack tracer
x86: entry_64 - introduce FTRACE_ frame macro v2
tracing/ftrace: add the printk-msg-only option
tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()
x86, bts: correctly report invalid bts records
...
Fixed up trivial conflict in scripts/recordmcount.pl due to SH bits
being already partly merged by the SH merge.
Impact: fix a crash/hard-reboot on certain configs while enabling cpu runtime
On some archs, the boot of a secondary cpu can have an early fragile state.
On x86-64, the pda is not initialized on the first stage of a cpu boot but
it is needed to get the cpu number and the current task pointer. This data
is needed during tracing. As they were dereferenced at this stage, we got a
crash while tracing a cpu being enabled at runtime.
Some other archs like ia64 can have such kind of issue too.
Changes on v2:
We dropped the previous solution of a per-arch called function to guess the
current state of a cpu. That could slow down the tracing.
This patch removes the -pg flag on arch/x86/kernel/cpu/common.c where
the low level cpu boot functions exist, on start_secondary() and a helper
function used at this stage.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, avoid sparse warnings, reduce kernel size a bit
Fixes these sparse warnings:
arch/x86/kernel/cpu/common.c:869:6: warning: symbol 'boot_cpu_stack' was not declared. Should it be static?
arch/x86/kernel/cpu/common.c:910:6: warning: symbol 'boot_exception_stacks' was not declared. Should it be static?
Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix wrong cache sharing detection on platforms supporting > 8 bit apicid's
In the presence of extended topology eumeration leaf 0xb provided
by cpuid, 32bit extended initial_apicid in cpuinfo_x86 struct will be
updated by detect_extended_topology(). At this instance, we should also
reinit the apicid (which could also potentially be extended to 32bit).
With out this there will potentially be duplicate apicid's populated in the
per cpu's cpuinfo_x86 struct, resulting in wrong cache sharing topology etc
detected by init_intel_cacheinfo().
Reported-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Impact: Remove cpumask_t's from stack.
Simple transition to work_on_cpu(), rather than cpumask games.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robert Richter <robert.richter@amd.com>
Cc: jacob.shin@amd.com
Impact: remove cpumask_t from stack.
We should not try to save and restore cpus_allowed on current.
We can't use work_on_cpu() here, since it's in the hotplug cpu path
(if anyone else tries to get the hotplug lock from a workqueue we
could deadlock against them).
Fortunately, we can just use smp_call_function_single() since the
function can run from an interrupt.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Impact: fix disabled MCE after resume
Don't prevent multiple initialization of MCEs.
Back from early prehistory mcheck_init() has a reentry check. Presumably
that was needed in very old kernels to prevent it entering twice.
But as Andreas points out this prevents CPU hotplug (and therefore resume)
to correctly reinitialize MCEs when a AP boots again after being
offlined.
Just drop the check.
Reported-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: reward non-stop TSCs with good TSC-based clocksources, etc.
Add support for CPUID_0x80000007_Bit8 on Intel CPUs as well. This bit means
that the TSC is invariant with C/P/T states and always runs at constant
frequency.
With Intel CPUs, we have 3 classes
* CPUs where TSC runs at constant rate and does not stop n C-states
* CPUs where TSC runs at constant rate, but will stop in deep C-states
* CPUs where TSC rate will vary based on P/T-states and TSC will stop in deep
C-states.
To cover these 3, one feature bit (CONSTANT_TSC) is not enough. So, add a
second bit (NONSTOP_TSC). CONSTANT_TSC indicates that the TSC runs at
constant frequency irrespective of P/T-states, and NONSTOP_TSC indicates
that TSC does not stop in deep C-states.
CPUID_0x8000000_Bit8 indicates both these feature bit can be set.
We still have CONSTANT_TSC _set_ and NONSTOP_TSC _not_set_ on some older Intel
CPUs, based on model checks. We can use TSC on such CPUs for time, as long as
those CPUs do not support/enter deep C-states.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: change calling convention of existing cpumask APIs
Most cpumask functions started with cpus_: these have been replaced by
cpumask_ ones which take struct cpumask pointers as expected.
These four functions don't have good replacement names; fortunately
they're rarely used, so we just change them over.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: paulus@samba.org
Cc: mingo@redhat.com
Cc: tony.luck@intel.com
Cc: ralf@linux-mips.org
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: cl@linux-foundation.org
Cc: srostedt@redhat.com
Impact: cleanup
Move the BTS bits from ptrace.c into ds.c.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new "power-tracer" ftrace plugin
This patch adds a C/P-state ftrace plugin that will generate
detailed statistics about the C/P-states that are being used,
so that we can look at detailed decisions that the C/P-state
code is making, rather than the too high level "average"
that we have today.
An example way of using this is:
mount -t debugfs none /sys/kernel/debug
echo cstate > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_enabled
sleep 1
echo 0 > /sys/kernel/debug/tracing/tracing_enabled
cat /sys/kernel/debug/tracing/trace | perl scripts/trace/cstate.pl > out.svg
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A workaround for AMD CPU family 11h erratum 311 might cause that the
P-state Status Register shows a "current P-state" which is larger than
the "current P-state limit" in P-state Current Limit Register. For the
wrong P-state value there is no ACPI _PSS object defined and
powernow-k8/cpufreq can't determine the proper CPU frequency for that
state.
As a consequence this can cause a panic during boot (potentially with
all recent kernel versions -- at least I have reproduced it with
various 2.6.27 kernels and with the current .28 series), as an
example:
powernow-k8: Found 1 AMD Turion(tm)X2 Ultra DualCore Mobile ZM-82 processors (2 \
)
powernow-k8: 0 : pstate 0 (2200 MHz)
powernow-k8: 1 : pstate 1 (1100 MHz)
powernow-k8: 2 : pstate 2 (600 MHz)
BUG: unable to handle kernel paging request at ffff88086e7528b8
IP: [<ffffffff80486361>] cpufreq_stats_update+0x4a/0x5f
PGD 202063 PUD 0
Oops: 0002 [#1] SMP
last sysfs file:
CPU 1
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.28-rc3-dirty #16
RIP: 0010:[<ffffffff80486361>] [<ffffffff80486361>] cpufreq_stats_update+0x4a/0\
f
Synaptics claims to have extended capabilities, but I'm not able to read them.<6\
6
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88006e7528c0
RDX: 00000000ffffffff RSI: ffff88006e54af00 RDI: ffffffff808f056c
RBP: 00000000fffee697 R08: 0000000000000003 R09: ffff88006e73f080
R10: 0000000000000001 R11: 00000000002191c0 R12: ffff88006fb83c10
R13: 00000000ffffffff R14: 0000000000000001 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88006fb50740(0000) knlGS:0000000000000000
Unable to initialize Synaptics hardware.
CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: ffff88086e7528b8 CR3: 0000000000201000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper (pid: 1, threadinfo ffff88006fb82000, task ffff88006fb816d0)
Stack:
ffff88006e74da50 0000000000000000 ffff88006e54af00 ffffffff804863c7
ffff88006e74da50 0000000000000000 00000000ffffffff 0000000000000000
ffff88006fb83c10 ffffffff8024b46c ffffffff808f0560 ffff88006fb83c10
Call Trace:
[<ffffffff804863c7>] ? cpufreq_stat_notifier_trans+0x51/0x83
[<ffffffff8024b46c>] ? notifier_call_chain+0x29/0x4c
[<ffffffff8024b561>] ? __srcu_notifier_call_chain+0x46/0x61
[<ffffffff8048496d>] ? cpufreq_notify_transition+0x93/0xa9
[<ffffffff8021ab8d>] ? powernowk8_target+0x1e8/0x5f3
[<ffffffff80486687>] ? cpufreq_governor_performance+0x1b/0x20
[<ffffffff80484886>] ? __cpufreq_governor+0x71/0xa8
[<ffffffff80484b21>] ? __cpufreq_set_policy+0x101/0x13e
[<ffffffff80485bcd>] ? cpufreq_add_dev+0x3f0/0x4cd
[<ffffffff8048577a>] ? handle_update+0x0/0x8
[<ffffffff803c2062>] ? sysdev_driver_register+0xb6/0x10d
[<ffffffff8056592c>] ? powernowk8_init+0x0/0x7e
[<ffffffff8048604c>] ? cpufreq_register_driver+0x8f/0x140
[<ffffffff80209056>] ? _stext+0x56/0x14f
[<ffffffff802c2234>] ? proc_register+0x122/0x17d
[<ffffffff802c23a0>] ? create_proc_entry+0x73/0x8a
[<ffffffff8025c259>] ? register_irq_proc+0x92/0xaa
[<ffffffff8025c2c8>] ? init_irq_proc+0x57/0x69
[<ffffffff807fc85f>] ? kernel_init+0x116/0x169
[<ffffffff8020cc79>] ? child_rip+0xa/0x11
[<ffffffff807fc749>] ? kernel_init+0x0/0x169
[<ffffffff8020cc6f>] ? child_rip+0x0/0x11
Code: 05 c5 83 36 00 48 c7 c2 48 5d 86 80 48 8b 04 d8 48 8b 40 08 48 8b 34 02 48\
RIP [<ffffffff80486361>] cpufreq_stats_update+0x4a/0x5f
RSP <ffff88006fb83b20>
CR2: ffff88086e7528b8
---[ end trace 0678bac75e67a2f7 ]---
Kernel panic - not syncing: Attempted to kill init!
In short, aftereffect of the wrong P-state is that
cpufreq_stats_update() uses "-1" as index for some array in
cpufreq_stats_update (unsigned int cpu)
{
...
if (stat->time_in_state)
stat->time_in_state[stat->last_index] =
cputime64_add(stat->time_in_state[stat->last_index],
cputime_sub(cur_time, stat->last_time));
...
}
Fortunately, the wrong P-state value is returned only if the core is
in P-state 0. This fix solves the problem by detecting the
out-of-range P-state, ignoring it, and using "0" instead.
Cc: Mark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Dave Jones <davej@redhat.com>
Impact: fix sparse build warning
Fix the following sparse warnings:
arch/x86/kernel/cpu/hypervisor.c:37:15: warning: symbol
'get_hypervisor_tsc_freq' was not declared. Should it be static?
arch/x86/kernel/cpu/hypervisor.c:53:16: warning: symbol
'init_hypervisor' was not declared. Should it be static?
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Cc: "Alok N Kataria" <akataria@vmware.com>
Cc: "Dan Hecht" <dhecht@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix sparse build warning
Fix the following sparse warnings:
arch/x86/kernel/cpu/vmware.c:69:5: warning: symbol 'vmware_platform'
was not declared. Should it be static?
arch/x86/kernel/cpu/vmware.c:89:15: warning: symbol
'vmware_get_tsc_khz' was not declared. Should it be static?
arch/x86/kernel/cpu/vmware.c:107:16: warning: symbol
'vmware_set_feature_bits' was not declared. Should it be static?
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Cc: "Alok N Kataria" <akataria@vmware.com>
Cc: "Dan Hecht" <dhecht@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: widen BTS/PEBS ptrace enablement to more CPU models
Move BTS initialisation out of an #ifdef CONFIG_X86_64 guard.
Assume core2 BTS and DS layout for future models of family 6 processors.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Should permit VMware detection on older platforms where the
vendor is changed. Could theoretically cause a regression if some
weird serial number scheme contains the string "VMware" by pure
chance. Seems unlikely, especially with the mixed case.
In some user configured cases, VMware may choose not to put a VMware specific
DMI string, but the product serial key is always there and is VMware specific.
Add a interface to check the serial key, when checking for VMware in the DMI
information.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: Fix possible failure to calibrate the TSC on Vmware near 4 GHz
The current version of the code to get the tsc frequency from
the VMware hypervisor, will be broken on processor with frequency
(4G-1) HZ, because on such processors eax will have UINT_MAX
and that would be legitimate.
We instead check that EBX did change to decide if we were able to
read the frequency from the hypervisor.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: Changes timebase calibration on Vmware.
Use the synthetic TSC_RELIABLE bit to workaround virtualization anomalies.
Virtual TSCs can be kept nearly in sync, but because the virtual TSC
offset is set by software, it's not perfect. So, the TSC
synchronization test can fail. Even then the TSC can be used as a
clocksource since the VMware platform exports a reliable TSC to the
guest for timekeeping purposes. Use this bit to check if we need to
skip the TSC sync checks.
Along with this also set the CONSTANT_TSC bit when on VMware, since we
still want to use TSC as clocksource on VM running over hardware which
has unsynchronized TSC's (opteron's), since the hypervisor will take
care of providing consistent TSC to the guest.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Signed-off-by: Dan Hecht <dhecht@vmware.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: Changes timebase calibration on Vmware.
v3->v2 : Abstract the hypervisor detection and feature (tsc_freq) request
behind a hypervisor.c file
v2->v1 : Add a x86_hyper_vendor field to the cpuinfo_x86 structure.
This avoids multiple calls to the hypervisor detection function.
This patch adds function to detect if we are running under VMware.
The current way to check if we are on VMware is following,
# check if "hypervisor present bit" is set, if so read the 0x40000000
cpuid leaf and check for "VMwareVMware" signature.
# if the above fails, check the DMI vendors name for "VMware" string
if we find one we query the VMware hypervisor port to check if we are
under VMware.
The DMI + "VMware hypervisor port check" is needed for older VMware products,
which don't implement the hypervisor signature cpuid leaf.
Also note that since we are checking for the DMI signature the hypervisor
port should never be accessed on native hardware.
This patch also adds a hypervisor_get_tsc_freq function, instead of
calibrating the frequency which can be error prone in virtualized
environment, we ask the hypervisor for it. We get the frequency from
the hypervisor by accessing the hypervisor port if we are running on VMware.
Other hypervisors too can add code to the generic routine to get frequency on
their platform.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Signed-off-by: Dan Hecht <dhecht@vmware.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: build fix on certain UP configs
fix:
arch/x86/kernel/cpu/common.c: In function 'cpu_init':
arch/x86/kernel/cpu/common.c:1141: error: 'boot_cpu_id' undeclared (first use in this function)
arch/x86/kernel/cpu/common.c:1141: error: (Each undeclared identifier is reported only once
arch/x86/kernel/cpu/common.c:1141: error: for each function it appears in.)
Pull in asm/smp.h on UP, so that we get the definition of
boot_cpu_id.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
fix:
arch/x86/kernel/cpu/common.c: In function 'early_identify_cpu':
arch/x86/kernel/cpu/common.c:553: error: 'struct cpuinfo_x86' has no member named 'cpu_index'
as cpu_index is only available on SMP.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix /proc/cpuinfo output on x86/Voyager
Ever since
| commit 92cb7612ae
| Author: Mike Travis <travis@sgi.com>
| Date: Fri Oct 19 20:35:04 2007 +0200
|
| x86: convert cpuinfo_x86 array to a per_cpu array
We've had an extra field in cpuinfo_x86 which is cpu_index.
Unfortunately, voyager has never initialised this, although the only
noticeable impact seems to be that /proc/cpuinfo shows all zeros for
the processor ids.
Anyway, fix this by initialising the boot CPU properly and setting the
index when the secondaries update.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix on x86/Voyager
Given commits like this:
| Author: Suresh Siddha <suresh.b.siddha@intel.com>
| Date: Tue Jul 29 10:29:19 2008 -0700
|
| x86, xsave: enable xsave/xrstor on cpus with xsave support
Which deliberately expose boot cpu dependence to pieces of the system,
I think it's time to explicitly have a variable for it to prevent this
continual misassumption that the boot CPU is zero.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix x86/Voyager boot
CONFIG_SMP is used for features which work on *all* x86 boxes.
CONFIG_X86_SMP is used for standard PC like x86 boxes (for things like
multi core and apics)
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Ingo said mtrr_cleanup() is big and ugly.
so break it up into more functions and make it more readable.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: fix section mismatch warning - apic_x2apic_phys
x86: fix section mismatch warning - apic_x2apic_cluster
x86: fix section mismatch warning - apic_x2apic_uv_x
x86: fix section mismatch warning - apic_physflat
x86: fix section mismatch warning - apic_flat
x86: memtest fix use of reserve_early()
x86 syscall.h: fix argument order
x86/tlb_uv: remove strange mc146818rtc include
x86: remove redundant KERN_DEBUG on pr_debug
x86: do_boot_cpu - check if we have ESR register
x86: MAINTAINERS change for AMD microcode patch loader
x86/proc: fix /proc/cpuinfo cpu offline bug
x86: call dmi-quirks for HP Laptops after early-quirks are executed
x86, kexec: fix hang on i386 when panic occurs while console_sem is held
MCE: Don't run 32bit machine checks with interrupts on
x86: SB600: skip IRQ0 override if it is not routed to INT2 of IOAPIC
x86: make variables static
* 'x86/um-header' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (26 commits)
x86: canonicalize remaining header guards
x86: drop double underscores from header guards
x86: Fix ASM_X86__ header guards
x86, um: get rid of uml-config.h
x86, um: get rid of arch/um/Kconfig.arch
x86, um: get rid of arch/um/os symlink
x86, um: get rid of excessive includes of uml-config.h
x86, um: get rid of header symlinks
x86, um: merge Kconfig.i386 and Kconfig.x86_64
x86, um: get rid of sysdep symlink
x86, um: trim the junk from uml ptrace-*.h
x86, um: take vm-flags.h to sysdep
x86, um: get rid of uml asm/arch
x86, um: get rid of uml highmem.h
x86, um: get rid of uml unistd.h
x86, um: get rid of system.h -> system.h include
x86, um: uml atomic.h is not needed anymore
x86, um: untangle uml ldt.h
x86, um: get rid of more uml asm/arch uses
x86, um: remove dead header (uml module-generic.h; never used these days)
...
Impact: fix missing CPUs in /proc/cpuinfo after CPU hotunplug/hotreplug
In my test, I found that if a cpu has been offline,
the next cpus may not be shown in the /proc/cpuinfo.
if one read() cannot consume the whole /proc/cpuinfo,
c_start() will be called again in the next read() calls.
And *pos has been increased by 1 by the caller(seq_read()).
if this time the cpu#*pos is offline, c_start() will return
NULL, and the next cpus can not be shown.
this fix use next_cpu_nr(*pos - 1, cpu_online_map) to
search the next unshown cpu.
the most easy way to reproduce this bug:
1) offline cpu#1 (cpu#0 is online)
2) dd ibs=2 if=/proc/cpuinfo
the result is that only cpu#0 is shown.
cpu#2 and cpu#3 .... cannot be shown in /proc/cpuinfo
it's bug.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
