linux-toradex.git, branch v3.2.9-rt16

kconfig-preempt-rt-full.patch

2012-03-06T16:18:04+00:00

Signed-off-by: Thomas Gleixner

kconfig-disable-a-few-options-rt.patch

2012-03-06T16:18:04+00:00

Disable stuff which is known to have issues on RT

Signed-off-by: Thomas Gleixner

cpu: Make hotplug.lock a "sleeping" spinlock on RT

2012-03-06T16:18:04+00:00

Tasks can block on hotplug.lock in pin_current_cpu(), but their state
might be != RUNNING. So the mutex wakeup will set the state
unconditionally to RUNNING. That might cause spurious unexpected
wakeups. We could provide a state preserving mutex_lock() function,
but this is semantically backwards. So instead we convert the
hotplug.lock() to a spinlock for RT, which has the state preserving
semantics already.

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/1330702617.25686.265.camel@gandalf.stny.rr.com
Signed-off-by: Thomas Gleixner

lglock/rt: Use non-rt for_each_cpu() in -rt code

2012-03-06T16:18:04+00:00

Currently the RT version of the lglocks() does a for_each_online_cpu()
in the name##_global_lock_online() functions. Non-rt uses its own
mask for this, and for good reason.

A task may grab a *_global_lock_online(), and in the mean time, one
of the CPUs goes offline. Now when that task does a *_global_unlock_online()
it releases all the locks *except* the one that went offline.

Now if that CPU were to come back on line, its lock is now owned by a
task that never released it when it should have.

This causes all sorts of fun errors. Like owners of a lock no longer
existing, or sleeping on IO, waiting to be woken up by a task that
happens to be blocked on the lock it never released.

Convert the RT versions to use the lglock specific cpumasks. As once
a CPU comes on line, the mask is set, and never cleared even when the
CPU goes offline. The locks for that CPU will still be taken and released.

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190345.374756214@goodmis.org
Signed-off-by: Thomas Gleixner

sched/rt: Fix wait_task_interactive() to test rt_spin_lock state

2012-03-06T16:18:04+00:00

The wait_task_interactive() will have a task sleep waiting for another
task to have a certain state. But it ignores the rt_spin_locks state
and can return with an incorrect result if the task it is waiting
for is blocked on a rt_spin_lock() and is waking up.

The rt_spin_locks save the tasks state in the saved_state field
and the wait_task_interactive() must also test that state.

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190345.979435764@goodmis.org
Signed-off-by: Thomas Gleixner

ring-buffer/rt: Check for irqs disabled before grabbing reader lock

2012-03-06T16:18:03+00:00

In RT the reader lock is a mutex and we can not grab it when preemption is
disabled. The in_atomic() check that is there does not check if irqs are
disabled. Add that check as well.

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190345.786365803@goodmis.org
Signed-off-by: Thomas Gleixner

futex/rt: Fix possible lockup when taking pi_lock in proxy handler

2012-03-06T16:18:03+00:00

When taking the pi_lock, we must disable interrupts because the
pi_lock can also be taken in an interrupt handler.

Use raw_spin_lock_irq() instead of raw_spin_lock().

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190345.165160680@goodmis.org
Signed-off-by: Thomas Gleixner

timer: Fix hotplug for -rt

2012-03-06T16:18:03+00:00

Revert the RT patch:
    Author: Ingo Molnar 
    Date:   Fri Jul 3 08:30:32 2009 -0500
    timers: fix timer hotplug on -rt

    Here we are in the CPU_DEAD notifier, and we must not sleep nor
    enable interrupts.

There's no problem with sleeping in this notifier.

But the get_cpu_var() had to be converted to a get_local_var().

Replace the previous fix with the get_local_var() convert.

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190344.948157137@goodmis.org
Signed-off-by: Thomas Gleixner

net: u64_stat: Protect seqcount

2012-03-06T16:18:03+00:00

On RT we must prevent that the writer gets preempted inside the write
section. Otherwise a preempting reader might spin forever.

Signed-off-by: Thomas Gleixner 
Cc: stable-rt@vger.kernel.org

fs: Protect open coded isize seqcount

2012-03-06T16:18:03+00:00

A writer might be preempted in the write side critical section on
RT. Disable preemption to avoid endless spinning of a preempting
reader.

Signed-off-by: Thomas Gleixner 
Cc: stable-rt@vger.kernel.org