linux-toradex.git/drivers/acpi/processor_throttling.c, branch v4.15-rc2

acpi/processor: Prevent cpu hotplug deadlock

2017-05-26T08:10:47+00:00

With the enhanced CPU hotplug lockdep coverage the following lockdep splat
happens:

======================================================
WARNING: possible circular locking dependency detected
4.12.0-rc2+ #84 Tainted: G        W      
------------------------------------------------------
cpuhp/1/15 is trying to acquire lock:
flush_work+0x39/0x2f0

but task is already holding lock:
cpuhp_thread_fun+0x30/0x160

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (cpuhp_state){+.+.+.}:
       lock_acquire+0xb4/0x200
       cpuhp_kick_ap_work+0x72/0x330
       _cpu_down+0x8b/0x100
       do_cpu_down+0x3e/0x60
       cpu_down+0x10/0x20
       cpu_subsys_offline+0x14/0x20
       device_offline+0x88/0xb0
       online_store+0x4c/0xa0
       dev_attr_store+0x18/0x30
       sysfs_kf_write+0x45/0x60
       kernfs_fop_write+0x156/0x1e0
       __vfs_write+0x37/0x160
       vfs_write+0xca/0x1c0
       SyS_write+0x58/0xc0
       entry_SYSCALL_64_fastpath+0x23/0xc2

-> #1 (cpu_hotplug_lock.rw_sem){++++++}:
       lock_acquire+0xb4/0x200
       cpus_read_lock+0x3d/0xb0
       apply_workqueue_attrs+0x17/0x50
       __alloc_workqueue_key+0x1e1/0x530
       scsi_host_alloc+0x373/0x480 [scsi_mod]
       ata_scsi_add_hosts+0xcb/0x130 [libata]
       ata_host_register+0x11a/0x2c0 [libata]
       ata_host_activate+0xf0/0x150 [libata]
       ahci_host_activate+0x13e/0x170 [libahci]
       ahci_init_one+0xa3a/0xd3f [ahci]
       local_pci_probe+0x45/0xa0
       work_for_cpu_fn+0x14/0x20
       process_one_work+0x1f9/0x690
       worker_thread+0x200/0x3d0
       kthread+0x138/0x170
       ret_from_fork+0x31/0x40

-> #0 ((&wfc.work)){+.+.+.}:
       __lock_acquire+0x11e1/0x13e0
       lock_acquire+0xb4/0x200
       flush_work+0x5c/0x2f0
       work_on_cpu+0xa1/0xd0
       acpi_processor_get_throttling+0x3d/0x50
       acpi_processor_reevaluate_tstate+0x2c/0x50
       acpi_soft_cpu_online+0x69/0xd0
       cpuhp_invoke_callback+0xb4/0x8b0
       cpuhp_up_callbacks+0x36/0xc0
       cpuhp_thread_fun+0x14e/0x160
       smpboot_thread_fn+0x1e8/0x300
       kthread+0x138/0x170
       ret_from_fork+0x31/0x40

other info that might help us debug this:

Chain exists of:
  (&wfc.work) --> cpu_hotplug_lock.rw_sem --> cpuhp_state

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(cpuhp_state);
                               lock(cpu_hotplug_lock.rw_sem);
                               lock(cpuhp_state);
  lock((&wfc.work));

 *** DEADLOCK ***

1 lock held by cpuhp/1/15:
cpuhp_thread_fun+0x30/0x160

stack backtrace:
CPU: 1 PID: 15 Comm: cpuhp/1 Tainted: G        W       4.12.0-rc2+ #84
Hardware name: Supermicro SYS-4048B-TR4FT/X10QBi, BIOS 1.1a 07/29/2015
Call Trace:
 dump_stack+0x85/0xc4
 print_circular_bug+0x209/0x217
 __lock_acquire+0x11e1/0x13e0
 lock_acquire+0xb4/0x200
 ? lock_acquire+0xb4/0x200
 ? flush_work+0x39/0x2f0
 ? acpi_processor_start+0x50/0x50
 flush_work+0x5c/0x2f0
 ? flush_work+0x39/0x2f0
 ? acpi_processor_start+0x50/0x50
 ? mark_held_locks+0x6d/0x90
 ? queue_work_on+0x56/0x90
 ? trace_hardirqs_on_caller+0x154/0x1c0
 ? trace_hardirqs_on+0xd/0x10
 ? acpi_processor_start+0x50/0x50
 work_on_cpu+0xa1/0xd0
 ? find_worker_executing_work+0x50/0x50
 ? acpi_processor_power_exit+0x70/0x70
 acpi_processor_get_throttling+0x3d/0x50
 acpi_processor_reevaluate_tstate+0x2c/0x50
 acpi_soft_cpu_online+0x69/0xd0
 cpuhp_invoke_callback+0xb4/0x8b0
 ? lock_acquire+0xb4/0x200
 ? padata_replace+0x120/0x120
 cpuhp_up_callbacks+0x36/0xc0
 cpuhp_thread_fun+0x14e/0x160
 smpboot_thread_fn+0x1e8/0x300
 kthread+0x138/0x170
 ? sort_range+0x30/0x30
 ? kthread_create_on_node+0x70/0x70
 ret_from_fork+0x31/0x40

The problem is that the work is scheduled on the current CPU from the
hotplug thread associated with that CPU.

It's not required to invoke these functions via the workqueue because the
hotplug thread runs on the target CPU already.

Check whether current is a per cpu thread pinned on the target CPU and
invoke the function directly to avoid the workqueue.

Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Sebastian Siewior 
Cc: "Rafael J. Wysocki" 
Cc: Steven Rostedt 
Cc: linux-acpi@vger.kernel.org
Cc: Len Brown 
Link: http://lkml.kernel.org/r/20170524081549.620489733@linutronix.de

ACPI/processor: Replace racy task affinity logic

2017-04-15T10:20:54+00:00

acpi_processor_get_throttling() requires to invoke the getter function on
the target CPU. This is achieved by temporarily setting the affinity of the
calling user space thread to the requested CPU and reset it to the original
affinity afterwards.

That's racy vs. CPU hotplug and concurrent affinity settings for that
thread resulting in code executing on the wrong CPU and overwriting the
new affinity setting.

acpi_processor_get_throttling() is invoked in two ways:

1) The CPU online callback, which is already running on the target CPU and
   obviously protected against hotplug and not affected by affinity
   settings.

2) The ACPI driver probe function, which is not protected against hotplug
   during modprobe.

Switch it over to work_on_cpu() and protect the probe function against CPU
hotplug.

Signed-off-by: Thomas Gleixner 
Cc: Fenghua Yu 
Cc: Tony Luck 
Cc: Herbert Xu 
Cc: "Rafael J. Wysocki" 
Cc: Peter Zijlstra 
Cc: Benjamin Herrenschmidt 
Cc: Sebastian Siewior 
Cc: Lai Jiangshan 
Cc: linux-acpi@vger.kernel.org
Cc: Viresh Kumar 
Cc: Michael Ellerman 
Cc: Tejun Heo 
Cc: "David S. Miller" 
Cc: Len Brown 
Link: http://lkml.kernel.org/r/20170412201042.785920903@linutronix.de
Signed-off-by: Thomas Gleixner

Replace with globally

2016-12-24T19:46:01+00:00

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*'
  sed -i -e "s!$PATT!#include !" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro 
Signed-off-by: Linus Torvalds

ACPI/processor: Convert to hotplug state machine

2016-09-19T19:44:29+00:00

Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: "Rafael J. Wysocki" 
Cc: Peter Zijlstra 
Cc: linux-acpi@vger.kernel.org
Cc: rt@linutronix.de
Cc: Len Brown 
Link: http://lkml.kernel.org/r/20160906170457.32393-12-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner

ACPI / processor: Avoid reserving IO regions too early

2016-06-01T23:57:50+00:00

Roland Dreier reports that one of his systems cannot boot because of
the changes made by commit ac212b6980d8 (ACPI / processor: Use common
hotplug infrastructure).

The problematic part of it is the request_region() call in
acpi_processor_get_info() that used to run at module init time before
the above commit and now it runs much earlier.  Unfortunately, the
region(s) reserved by it fall into a range the PCI subsystem attempts
to reserve for AHCI IO BARs.  As a result, the PCI reservation fails
and AHCI doesn't work, while previously the PCI reservation would
be made before acpi_processor_get_info() and it would succeed.

That request_region() call, however, was overlooked by commit
ac212b6980d8, as it is not necessary for the enumeration of the
processors.  It only is needed when the ACPI processor driver
actually attempts to handle them which doesn't happen before
loading the ACPI processor driver module.  Therefore that call
should have been moved from acpi_processor_get_info() into that
module.

Address the problem by moving the request_region() call in question
out of acpi_processor_get_info() and use the observation that the
region reserved by it is only needed if the FADT-based CPU
throttling method is going to be used, which means that it should
be sufficient to invoke it from acpi_processor_get_throttling_fadt().

Fixes: ac212b6980d8 (ACPI / processor: Use common hotplug infrastructure)
Reported-by: Roland Dreier 
Tested-by: Roland Dreier 
Signed-off-by: Rafael J. Wysocki

ACPI: Remove FSF mailing addresses

2015-07-08T00:27:32+00:00

There is no need to carry potentially outdated Free Software Foundation
mailing address in file headers since the COPYING file includes it.

Signed-off-by: Jarkko Nikula 
Signed-off-by: Rafael J. Wysocki

ACPI / processor: Rework processor throttling with work_on_cpu()

2014-02-26T23:21:05+00:00

acpi_processor_set_throttling() uses set_cpus_allowed_ptr() to make
sure that the (struct acpi_processor)->acpi_processor_set_throttling()
callback will run on the right CPU.  However, the function may be
called from a worker thread already bound to a different CPU in which
case that won't work.

Make acpi_processor_set_throttling() use work_on_cpu() as appropriate
instead of abusing set_cpus_allowed_ptr().

Reported-and-tested-by: Jiri Olsa 
Signed-off-by: Lan Tianyu 
Cc: All applicable 
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki

ACPI: Clean up inclusions of ACPI header files

2013-12-07T00:03:14+00:00

Replace direct inclusions of ,  and
, which are incorrect, with 
inclusions and remove some inclusions of those files that aren't
necessary.

First of all, ,  and 
should not be included directly from any files that are built for
CONFIG_ACPI unset, because that generally leads to build warnings about
undefined symbols in !CONFIG_ACPI builds.  For CONFIG_ACPI set,
 includes those files and for CONFIG_ACPI unset it
provides stub ACPI symbols to be used in that case.

Second, there are ordering dependencies between those files that always
have to be met.  Namely, it is required that  be included
prior to  so that the acpi_pci_root declarations the
latter depends on are always there.  And  which provides
basic ACPICA type declarations should always be included prior to any other
ACPI headers in CONFIG_ACPI builds.  That also is taken care of including
 as appropriate.

Signed-off-by: Lv Zheng 
Cc: Greg Kroah-Hartman 
Cc: Matthew Garrett 
Cc: Tony Luck 
Cc: "H. Peter Anvin" 
Acked-by: Bjorn Helgaas  (drivers/pci stuff)
Acked-by: Konrad Rzeszutek Wilk  (Xen stuff)
Signed-off-by: Rafael J. Wysocki

ACPI: suppress compiler warnings in processor_throttling.c

2013-03-24T23:05:48+00:00

This patch fixes following compiler warnings when build via make W=1:

drivers/acpi/processor_throttling.c: In function ‘acpi_processor_throttling_init’:
drivers/acpi/processor_throttling.c:216:40: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]

Signed-off-by: Andy Shevchenko 
Signed-off-by: Rafael J. Wysocki

ACPI throttling: fix endian bug in acpi_read_throttling_status()

2012-03-30T20:06:12+00:00

Using a u64 here creates an endian bug.  We store a u32 number in the
top byte which is a larger number than intended on big endian systems.
There is no reason to use a 64 bit data type here, I guess it was just
an oversight.

I removed the initialization to zero as well.  It's needed with a u64
but with a u32, the variable gets initialized properly inside the call
to acpi_os_read_port().

Signed-off-by: Dan Carpenter 
Signed-off-by: Len Brown