linux.git/arch/metag/kernel, branch v3.11

metag: delete __cpuinit usage from all metag files

2013-07-14T23:36:54+00:00

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/metag uses of the __cpuinit macros from
all C files.  Currently metag does not have any __CPUINIT used in
assembly files.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: James Hogan 
Acked-by: James Hogan 
Signed-off-by: Paul Gortmaker

Merge tag 'metag-for-v3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag

2013-07-06T19:39:39+00:00

Pull Metag architecture changes from James Hogan:
 - Infrastructure and DT files for TZ1090 SoC (pin control drivers
   already merged via pinctrl tree).
 - Panic on boot instead of just warning if cache aliasing possible.
 - Various SMP/hotplug fixes.
 - Various other randconfig/sparse fixes.

* tag 'metag-for-v3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag: (24 commits)
  metag: move EXPORT_SYMBOL(csum_partial) to metag_ksyms.c
  metag: cpu hotplug: route_irq: preserve irq mask
  metag: kick: add missing irq_enter/exit to kick_handler()
  metag: smp: don't spin waiting for CPU to start
  metag: smp: enable irqs after set_cpu_online
  metag: use clear_tasks_mm_cpumask()
  metag: tz1090: select and instantiate pinctrl-tz1090-pdc
  metag: tz1090: select and instantiate pinctrl-tz1090
  metag: don't check for cache aliasing on smp cpu boot
  metag: panic if cache aliasing possible
  metag: *.dts: include using preprocessor
  metag: add  symlink
  metag/.gitignore: Extend the *.dtb pattern to match the dtb.S files
  metag/traps: include setup.h for the per_cpu_trap_init declaration
  metag/traps: Mark die() as __noreturn to match the declaration.
  metag/processor.h: Add missing cpuinfo_op declaration.
  metag/setup: Restrict scope for the capabilities variable
  metag/mm/cache: Restrict scope for metag_lnkget_probe
  metag/asm/irq.h: Declare init_IRQ
  metag/kernel/irq.c: Declare root_domain as static
  ...

metag: move EXPORT_SYMBOL(csum_partial) to metag_ksyms.c

2013-07-04T09:00:02+00:00

Move EXPORT_SYMBOL(csum_partial) from lib/checksum.c into metag_ksyms.c
so that it doesn't get omitted by the static linker if it's not used by
any other statically linked code, which can result in undefined symbols
when building modules.

For example a randconfig caused the following error:
ERROR: "csum_partial" [fs/reiserfs/reiserfs.ko] undefined!

Signed-off-by: James Hogan

metag: cpu hotplug: route_irq: preserve irq mask

2013-07-02T13:12:22+00:00

The route_irq() function needs to preserve the irq mask by using the
_irqsave/irqrestore variants of raw spin lock functions instead of the
_irq variants. This is because it is called from __cpu_disable() (via
migrate_irqs()), which is called with IRQs disabled, so using the _irq
variants re-enables IRQs.

This appears to have been causing occasional hits of the
BUG_ON(!irqs_disabled()) in __irq_work_run() during CPU hotplug soak
testing:
  BUG: failure at kernel/irq_work.c:122/__irq_work_run()!

Signed-off-by: James Hogan 
Acked-by: Thomas Gleixner 
Reviewed-by: Srivatsa S. Bhat

metag: kick: add missing irq_enter/exit to kick_handler()

2013-07-02T13:12:08+00:00

kick_handler() doesn't have an irq_enter/exit pair, but it's used for
handling SMP IPIs which require work to be done in softirqs, which are
invoked from irq_exit() when the hard irq nest count reaches 0.

The scheduler_ipi() callback in the IPI handler calls irq_enter/exit
itself, but this is inside kick_handler()'s spin lock critical section,
so if an invoked softirq issues an IPI the kick_handler() will be
re-entered on the same CPU and will deadlock.

This is easily fixed by adding the missing irq_enter/exit to
kick_handler() so that the hard irq nest count doesn't reach 0 until
after the spin lock has been released.

Ideally the spin lock protected handler list will also be replaced by a
lockless RCU protected list since it is certainly mostly read. That can
be done in a later change though.

Signed-off-by: James Hogan 
Acked-by: Thomas Gleixner

metag: smp: don't spin waiting for CPU to start

2013-07-02T10:03:52+00:00

Use a completion to block until a secondary CPU has started up, like ARM
do, instead of a loop of udelays.

On Meta, SMP is really SMT, with each "CPU" being a different hardware
thread on the same Meta processor core, so as well as being more
efficient and latency friendly, using a completion prevents the bogomips
of the secondary CPU from being drastically skewed every time by the
execution of the tight in-cache udelay loop on the other CPU.

Signed-off-by: James Hogan 
Acked-by: Thomas Gleixner 
Reviewed-by: "Srivatsa S. Bhat"

metag: smp: enable irqs after set_cpu_online

2013-07-02T10:03:51+00:00

In secondary_start_kernel() interrupts should be enabled with
local_irq_enable() after the cpu is marked as online with
set_cpu_online(). Otherwise it's possible for a timer interrupt to
trigger a softirq, which if the cpu is marked as offline may have it's
affinity altered.

Reported-by: Kirill Tkhai 
Signed-off-by: James Hogan 
Acked-by: Thomas Gleixner 
Reviewed-by: "Srivatsa S. Bhat" 
Cc: Kirill Tkhai

metag: use clear_tasks_mm_cpumask()

2013-07-02T10:03:51+00:00

Checking for process->mm is not enough because process' main thread may
exit or detach its mm via use_mm(), but other threads may still have a
valid mm.

To fix this we would need to use find_lock_task_mm(), which would walk
up all threads and returns an appropriate task (with task lock held).

clear_tasks_mm_cpumask() was introduced in v3.5-rc1 to fix this issue,
so let's use it for metag too.

Signed-off-by: James Hogan 
Cc: "Srivatsa S. Bhat" 
Cc: Thomas Gleixner 
Cc: Oleg Nesterov 
Cc: Anton Vorontsov

metag: don't check for cache aliasing on smp cpu boot

2013-06-27T12:49:48+00:00

The cache configuration of the boot cpu is now duplicated to secondary
cpus, so there's no need to check for cache aliasing again when a
secondary cpu is booted. Therefore remove the check from
secondary_start_kernel().

Signed-off-by: James Hogan

metag: panic if cache aliasing possible

2013-06-27T12:49:48+00:00

If the cache and page size configuration allows for cache aliasing to
occur we warn on boot, but the log messages are easy to miss and will
result is random crashes occuring in userland. Let's panic too in this
case so that the user immediately knows they need to fix the cache
configuration or configured page size.

Also fix the warning messages which display the cache and page sizes to
include newlines, and add the word "Potential" since an actual cache
alias hasn't been detected.

Signed-off-by: James Hogan