Converting the cpu hotplug locking to a percpu rwsem unearthed hidden lock
ordering problems.
There is a wide range of locks involved in this: kprobe_mutex,
jump_label_mutex, ftrace_lock, text_mutex, event_mutex, module_mutex,
func_hash->regex_lock and a gazillion of lock order permutations with
nested get_online_cpus() calls.
Some of those permutations are potential deadlocks even with the current
nesting hotplug locking scheme, but they can't be discovered by lockdep.
The conversion of the hotplug locking to a percpu rwsem requires to prevent
nested locking, so it's required to take the hotplug rwsem early in the
call chain and establish a proper lock order.
After quite some analysis and going down the wrong road severa times the
following lock order has been chosen:
kprobe_mutex -> cpus_rwsem -> jump_label_mutex -> text_mutex
For kprobes which hook on an ftrace function trace point, it's required to
drop cpus_rwsem before calling into the ftrace code to avoid a deadlock on
the func_hash->regex_lock.
[ Steven: Ftrace interaction fixes ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/20170524081549.104864779@linutronix.de
The conversion of the hotplug locking to a percpu rwsem unearthed lock
ordering issues all over the place.
The jump_label code has two issues:
1) Nested get_online_cpus() invocations
2) Ordering problems vs. the cpus rwsem and the jump_label_mutex
To cure these, the following lock order has been established;
cpus_rwsem -> jump_label_lock -> text_mutex
Even if not all architectures need protection against CPU hotplug, taking
cpus_rwsem before jump_label_lock is now mandatory in code pathes which
actually modify code and therefor need text_mutex protection.
Move the get_online_cpus() invocations into the core jump label code and
establish the proper lock order where required.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: "David S. Miller" <davem@davemloft.net>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Link: http://lkml.kernel.org/r/20170524081549.025830817@linutronix.de
perf, tracing, kprobes and jump_labels have a gazillion of ways to create
dependency lock chains. Some of those involve nested invocations of
get_online_cpus().
The conversion of the hotplug locking to a percpu rwsem requires to avoid
such nested calls. sys_perf_event_open() protects most of the syscall logic
against cpu hotplug. This causes nested calls and lock inversions versus
ftrace and kprobes in various interesting ways.
It's impossible to move the hotplug locking to the outer end of all call
chains in the involved facilities, so the hotplug protection in
sys_perf_event_open() needs to be solved differently.
Introduce 'pmus_mutex' which protects a perf private online cpumask. This
mutex is taken when the mask is updated in the cpu hotplug callbacks and
can be taken in sys_perf_event_open() to protect the swhash setup/teardown
code and when the final judgement about a valid event has to be made.
[ tglx: Produced changelog and fixed the swhash interaction ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: http://lkml.kernel.org/r/20170524081548.930941109@linutronix.de
Converting the hotplug locking, i.e. get_online_cpus(), to a percpu rwsem
unearthed a circular lock dependency which was hidden from lockdep due to
the lockdep annotation of get_online_cpus() which prevents lockdep from
creating full dependency chains.
CPU0 CPU1
---- ----
lock((&wfc.work));
lock(cpu_hotplug_lock.rw_sem);
lock((&wfc.work));
lock(cpu_hotplug_lock.rw_sem);
This dependency is established via acpi_processor_start() which calls into
the work queue code. And the work queue code establishes the reverse
dependency.
This is not a problem of get_online_cpus() recursion, it's a possible
deadlock undetected by lockdep so far.
The cure is to use cpu_hotplug_disable() instead of get_online_cpus() to
protect the probing from acpi_processor_start().
There is a side effect to this: cpu_hotplug_disable() makes a concurrent
cpu hotplug attempt via the sysfs interfaces fail with -EBUSY, but that
probing usually happens during the boot process where no interaction is
possible. Any later invocations are infrequent enough and concurrent
hotplug attempts are so unlikely that the danger of user space visible
regressions is very close to zero. Anyway, thats preferrable over a real
deadlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-acpi@vger.kernel.org
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/20170524081548.851588594@linutronix.de
pci_call_probe() can called recursively when a physcial function is probed
and the probing creates virtual functions, which are populated via
pci_bus_add_device() which in turn can end up calling pci_call_probe()
again.
The code has an interesting way to prevent recursing into the workqueue
code. That's accomplished by a check whether the current task runs already
on the numa node which is associated with the device.
While that works to prevent the recursion into the workqueue code, it's
racy versus normal execution as there is no guarantee that the node does
not vanish after the check.
There is another issue with this code. It dereferences cpumask_of_node()
unconditionally without checking whether the node is available.
Make the detection reliable by:
- Mark a probed device as 'is_probed' in pci_call_probe()
- Check in pci_call_probe for a virtual function. If it's a virtual
function and the associated physical function device is marked
'is_probed' then this is a recursive call, so the call can be invoked in
the calling context.
- Add a check whether the node is online before dereferencing it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-pci@vger.kernel.org
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081548.771457199@linutronix.de
Converting the hotplug locking, i.e. get_online_cpus(), to a percpu rwsem
unearthed a circular lock dependency which was hidden from lockdep due to
the lockdep annotation of get_online_cpus() which prevents lockdep from
creating full dependency chains. There are several variants of this. And
example is:
Chain exists of:
cpu_hotplug_lock.rw_sem --> drm_global_mutex --> &item->mutex
CPU0 CPU1
---- ----
lock(&item->mutex);
lock(drm_global_mutex);
lock(&item->mutex);
lock(cpu_hotplug_lock.rw_sem);
because there are dependencies through workqueues. The call chain is:
get_online_cpus
apply_workqueue_attrs
__alloc_workqueue_key
ttm_mem_global_init
ast_ttm_mem_global_init
drm_global_item_ref
ast_mm_init
ast_driver_load
drm_dev_register
drm_get_pci_dev
ast_pci_probe
local_pci_probe
work_for_cpu_fn
process_one_work
worker_thread
This is not a problem of get_online_cpus() recursion, it's a possible
deadlock undetected by lockdep so far.
The cure is to use cpu_hotplug_disable() instead of get_online_cpus() to
protect the PCI probing.
There is a side effect to this: cpu_hotplug_disable() makes a concurrent
cpu hotplug attempt via the sysfs interfaces fail with -EBUSY, but PCI
probing usually happens during the boot process where no interaction is
possible. Any later invocations are infrequent enough and concurrent
hotplug attempts are so unlikely that the danger of user space visible
regressions is very close to zero. Anyway, thats preferrable over a real
deadlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-pci@vger.kernel.org
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081548.691198590@linutronix.de
If intel_snb_check_microcode() is invoked via
microcode_init -> perf_check_microcode -> intel_snb_check_microcode
then get_online_cpus() is invoked nested. This works with the current
implementation of get_online_cpus() but prevents converting it to a percpu
rwsem.
intel_snb_check_microcode() is also invoked from intel_sandybridge_quirk()
unprotected.
Drop get_online_cpus() from intel_snb_check_microcode() and add it to
intel_sandybridge_quirk() so both call sites are protected.
Convert *_online_cpus() to the new interfaces while at it.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20170524081548.594862191@linutronix.de
Currently only the PCIe driver supports metadata, so we should not claim
integrity support for the other drivers. This prevents nasty crashes
with targets that advertise metadata support on fabrics.
Also use the opportunity to factor out some code into a separate helper
that isn't even compiled if CONFIG_BLK_DEV_INTEGRITY is disabled.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
So that we can have more flags for transport-specific behavior.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
This is what most of the code already does and gives much more useful
prefixes than the device embedded in the pci_dev.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Several files are used to construct PCM core module, a.k.a snd-pcm.
Although available APIs are described in 'include/sound/pcm.h', some of
them are not exported as symbols in kernel space. Such APIs are just for
module local usage.
This commit adds module local header file and move some function prototypes
into it so that scopes of them are controlled properly and developers
get no confusion from unavailable symbols.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
We currently have three device nodes for the same USB hardware
block, as evident by the reuse of the same reg address multiple
times. Now that the chipidea driver fully supports OTG with the
MSM wrapper we can collapse all these nodes into one USB device
node, reflecting the true nature of the hardware.
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
We currently have three device nodes for the same USB hardware
block, as evident by the reuse of the same reg address multiple
times. Now that the chipidea driver fully supports OTG with the
MSM wrapper we can collapse the three nodes into one USB device
node, reflecting the true nature of the hardware.
Since we're here, we also mark the irq trigger flags correctly,
as IRQ_TYPE_LEVEL_HIGH instead of IRQ_TYPE_NONE.
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
This USB controller has two phys, so add them both underneath the
ULPI bus, but only enable one of them based on the board
configuration. To get OTG to work, we need to add the id and vbus
detection info and also populate the regulators for the vbus
supply.
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
These regulators are controlled by the SPMI regulator driver
instead of the RPM regulator driver in the downstream android
kernel sources. Let's remove them from the DTS here because
they'll never be used by the RPM regulator driver.
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
A bunch of bug fixes:
- Fix display flickering on some chips at high refresh rates
- suspend/resume fix
- hotplug fix
- a couple of segfault fixes for certain cases
* 'drm-fixes-4.12' of git://people.freedesktop.org/~agd5f/linux:
drm/amdgpu: fix null point error when rmmod amdgpu.
drm/amd/powerplay: fix a signedness bugs
drm/amdgpu: fix NULL pointer panic of emit_gds_switch
drm/radeon: Unbreak HPD handling for r600+
drm/amd/powerplay/smu7: disable mclk switching for high refresh rates
drm/amd/powerplay/smu7: add vblank check for mclk switching (v2)
drm/radeon/ci: disable mclk switching for high refresh rates (v2)
drm/amdgpu/ci: disable mclk switching for high refresh rates (v2)
drm/amdgpu: fix fundamental suspend/resume issue
Core Changes:
- Don't drop vblank reference more than once in cases of ww retry (Daniel)
Driver Changes:
- radeon: Fix oops during radeon probe trying to reference wrong device (Lukas)
- qxl: Avoid sleeping while in atomic context on cursor update (Gabriel)
- gma500: Use VBT mode instead of pre-programmed mode for LVDS (Patrik)
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
* tag 'drm-misc-fixes-2017-05-25' of git://anongit.freedesktop.org/git/drm-misc:
drm/gma500/psb: Actually use VBT mode when it is found
drm: Fix deadlock retry loop in page_flip_ioctl
drm: qxl: Delay entering atomic context during cursor update
drm/radeon: Fix oops upon driver load on PowerXpress laptops
This patch converts the ds1307 driver to using regmap. It's a rather
big patch and I can test with DS3231 only. With this chip it's
working fine.
I'd appreciate if people with other supported hardware could test as
well.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Update of maintainers entry for Samsung SoC.
* tag 'samsung-fixes-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux:
MAINTAINERS: Remove Javier Martinez Canillas as reviewer for Exynos
Signed-off-by: Olof Johansson <olof@lixom.net>
This pull request contains Broadcom ARM-based SoCs Device Tree fixes for 4.12,
please pull the following:
- Phil provides a fix for the BCM283x (Raspberry Pi) by flagging the first
4KiB of physical memory as a reserved region in order to let the secondary
cores successfully spin until they are brought online
* tag 'arm-soc/for-4.12/devicetree-fixes-2' of http://github.com/Broadcom/stblinux:
ARM: dts: bcm283x: Reserve first page for firmware
Signed-off-by: Olof Johansson <olof@lixom.net>
Enable some very core config options used on 64bit Rockchip socs.
As built-in driver enable the Rockchip spi driver as well as the
cros-ec-spi and cros-ec keyboard driver, as this may be helpful
in case an initrd does not work as expected and drops the user
into a shell. Another built-in is the fan53555 regulator driver,
as it and its register-compatible cousins Silergy syr827 and syr828
are often used on Rockchip socs as cpu-supply next to regular pmic.
The rest can be enabled as modules and contains the pcie host
controller and its phy, the sucessive approximation adc (saradc)
that gets often used for additional buttons on Rockchip boards
as well as the adc-keys Keyboard driver for these keys.
The cros-ec-pwm also can be a module, as it is normally only used to
drive display backlights as well as the Rockchip thermal controller
that allows to read the cpu and gpu temperatures and affect frequency
scaling if necessary.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Olof Johansson <olof@lixom.net>
