linux-toradex.git/kernel, branch v3.2-rt10

kconfig-preempt-rt-full.patch

2012-01-16T19:00:37+00:00

Signed-off-by: Thomas Gleixner

wait-simple: Simple waitqueue implementation

2012-01-16T19:00:36+00:00

wait_queue is a swiss army knife and in most of the cases the
complexity is not needed. For RT waitqueues are a constant source of
trouble as we can't convert the head lock to a raw spinlock due to
fancy and long lasting callbacks.

Provide a slim version, which allows RT to replace wait queues. This
should go mainline as well, as it lowers memory consumption and
runtime overhead.

Signed-off-by: Thomas Gleixner

sysrq: Allow immediate Magic SysRq output for PREEMPT_RT_FULL

2012-01-16T19:00:36+00:00

Add a CONFIG option to allow the output from Magic SysRq to be output
immediately, even if this causes large latencies.

If PREEMPT_RT_FULL, printk() will not try to acquire the console lock
when interrupts or preemption are disabled.  If the console lock is
not acquired the printk() output will be buffered, but will not be
output immediately. Some drivers call into the Magic SysRq code
with interrupts or preemption disabled, so the output of Magic SysRq
will be buffered instead of printing immediately if this option is
not selected.

Even with this option selected, Magic SysRq output will be delayed
if the attempt to acquire the console lock fails.

Signed-off-by: Frank Rowand 
Link: http://lkml.kernel.org/r/4E7CEF60.5020508@am.sony.com
Signed-off-by: Thomas Gleixner

add /sys/kernel/realtime entry

2012-01-16T19:00:35+00:00

Add a /sys/kernel entry to indicate that the kernel is a
realtime kernel.

Clark says that he needs this for udev rules, udev needs to evaluate
if its a PREEMPT_RT kernel a few thousand times and parsing uname
output is too slow or so.

Are there better solutions? Should it exist and return 0 on !-rt?

Signed-off-by: Clark Williams 
Signed-off-by: Peter Zijlstra

kgdb/serial: Short term workaround

2012-01-16T19:00:35+00:00

On 07/27/2011 04:37 PM, Thomas Gleixner wrote:
>  - KGDB (not yet disabled) is reportedly unusable on -rt right now due
>    to missing hacks in the console locking which I dropped on purpose.
>

To work around this in the short term you can use this patch, in
addition to the clocksource watchdog patch that Thomas brewed up.

Comments are welcome of course.  Ultimately the right solution is to
change separation between the console and the HW to have a polled mode
+ work queue so as not to introduce any kind of latency.

Thanks,
Jason.

printk: Disable migration instead of preemption

2012-01-16T19:00:34+00:00

There is no need do disable preemption in vprintk(), disable_migrate()
is sufficient. This fixes the following bug in -rt:

[   14.759233] BUG: sleeping function called from invalid context
at /home/rw/linux-rt/kernel/rtmutex.c:645
[   14.759235] in_atomic(): 1, irqs_disabled(): 0, pid: 547, name: bash
[   14.759244] Pid: 547, comm: bash Not tainted 3.0.12-rt29+ #3
[   14.759246] Call Trace:
[   14.759301]  [] __might_sleep+0xeb/0xf0
[   14.759318]  [] rt_spin_lock_fastlock.constprop.9+0x21/0x43
[   14.759336]  [] rt_spin_lock+0xe/0x10
[   14.759354]  [] serial8250_console_write+0x81/0x121
[   14.759366]  [] __call_console_drivers+0x7c/0x93
[   14.759369]  [] _call_console_drivers+0x5c/0x60
[   14.759372]  [] console_unlock+0x147/0x1a2
[   14.759374]  [] vprintk+0x3ea/0x462
[   14.759383]  [] printk+0x51/0x53
[   14.759399]  [] ? proc_reg_poll+0x9a/0x9a
[   14.759403]  [] __handle_sysrq+0x50/0x14d
[   14.759406]  [] write_sysrq_trigger+0x4b/0x53
[   14.759408]  [] ? __handle_sysrq+0x14d/0x14d
[   14.759410]  [] proc_reg_write+0x9f/0xbe
[   14.759426]  [] vfs_write+0xac/0xf3
[   14.759429]  [] ? fget_light+0x3a/0x9b
[   14.759431]  [] sys_write+0x4a/0x6e
[   14.759438]  [] system_call_fastpath+0x16/0x1b

Signed-off-by: Richard Weinberger 
Link: http://lkml.kernel.org/r/1323696956-11445-1-git-send-email-rw@linutronix.de
Signed-off-by: Thomas Gleixner

console-make-rt-friendly.patch

2012-01-16T19:00:33+00:00

Signed-off-by: Thomas Gleixner

x86-no-perf-irq-work-rt.patch

2012-01-16T19:00:33+00:00

Signed-off-by: Thomas Gleixner

hotplug-stuff.patch

2012-01-16T19:00:33+00:00

Do not take lock for non handled cases (might be atomic context)

Signed-off-by: Thomas Gleixner

workqueue: Use get_cpu_light() in flush_gcwq()

2012-01-16T19:00:33+00:00

BUG: sleeping function called from invalid context at kernel/rtmutex.c:645
in_atomic(): 1, irqs_disabled(): 0, pid: 1739, name: bash
Pid: 1739, comm: bash Not tainted 3.0.6-rt17-00284-gb76d419 #3
Call Trace:
 [] ? printk+0x1d/0x20
 [] __might_sleep+0xe6/0x110
 [] rt_spin_lock+0x1c/0x30
 [] flush_gcwq+0x236/0x320
 [] ? kfree+0xe1/0x1a0
 [] ? __cpufreq_remove_dev+0xf8/0x260
 [] ? rt_down_write+0xd/0x10
 [] workqueue_cpu_down_callback+0x26/0x2d
 [] notifier_call_chain+0x45/0x60
 [] __raw_notifier_call_chain+0x1e/0x30
 [] __cpu_notify+0x24/0x40
 [] _cpu_down+0xdf/0x330
 [] cpu_down+0x30/0x50
 [] store_online+0x50/0xa7
 [] ? acpi_os_map_memory+0xec/0xec
 [] sysdev_store+0x2a/0x40
 [] sysfs_write_file+0xa4/0x100
 [] vfs_write+0xa2/0x170
 [] ? sysfs_poll+0x90/0x90
 [] sys_write+0x42/0x70
 [] sysenter_do_call+0x12/0x2d
CPU 1 is now offline
SMP alternatives: switching to UP code
SMP alternatives: switching to SMP code
Booting Node 0 Processor 1 APIC 0x1
smpboot cpu 1: start_ip = 9b000
Initializing CPU#1
BUG: sleeping function called from invalid context at kernel/rtmutex.c:645
in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: kworker/0:0
Pid: 0, comm: kworker/0:0 Not tainted 3.0.6-rt17-00284-gb76d419 #3
Call Trace:
 [] ? printk+0x1d/0x20
 [] __might_sleep+0xe6/0x110
 [] rt_spin_lock+0x1c/0x30
 [] workqueue_cpu_up_callback+0x56/0xf3
 [] notifier_call_chain+0x45/0x60
 [] __raw_notifier_call_chain+0x1e/0x30
 [] __cpu_notify+0x24/0x40
 [] cpu_notify+0x1c/0x20
 [] notify_cpu_starting+0x1e/0x20
 [] smp_callin+0xfb/0x10e
 [] start_secondary+0x19/0xd7
NMI watchdog enabled, takes one hw-pmu counter.
Switched to NOHz mode on CPU #1

Signed-off-by: Yong Zhang 
Link: http://lkml.kernel.org/r/1318762607-2261-5-git-send-email-yong.zhang0@gmail.com
Signed-off-by: Thomas Gleixner