linux.git/block, branch v3.19-rc2

Revert "blk-mq: Micro-optimize bt_get()"

2014-12-15T15:30:26+00:00

This reverts commit 52f7eb945f2ba62b324bb9ae16d945326a961dcf.

The optimization is only really safe for a single queue, otherwise
'bs' and 'bt' can indeed change, and if we don't do a finish_wait()
for each loop, we'll potentially change the wait structure and
corrupt task wait list.

Reported-by: Jan Kara

Merge branch 'for-3.19/core' of git://git.kernel.dk/linux-block

2014-12-13T22:14:23+00:00

Pull block driver core update from Jens Axboe:
 "This is the pull request for the core block IO changes for 3.19.  Not
  a huge round this time, mostly lots of little good fixes:

   - Fix a bug in sysfs blktrace interface causing a NULL pointer
     dereference, when enabled/disabled through that API.  From Arianna
     Avanzini.

   - Various updates/fixes/improvements for blk-mq:

        - A set of updates from Bart, mostly fixing buts in the tag
          handling.

        - Cleanup/code consolidation from Christoph.

        - Extend queue_rq API to be able to handle batching issues of IO
          requests. NVMe will utilize this shortly. From me.

        - A few tag and request handling updates from me.

        - Cleanup of the preempt handling for running queues from Paolo.

        - Prevent running of unmapped hardware queues from Ming Lei.

        - Move the kdump memory limiting check to be in the correct
          location, from Shaohua.

        - Initialize all software queues at init time from Takashi. This
          prevents a kobject warning when CPUs are brought online that
          weren't online when a queue was registered.

   - Single writeback fix for I_DIRTY clearing from Tejun.  Queued with
     the core IO changes, since it's just a single fix.

   - Version X of the __bio_add_page() segment addition retry from
     Maurizio.  Hope the Xth time is the charm.

   - Documentation fixup for IO scheduler merging from Jan.

   - Introduce (and use) generic IO stat accounting helpers for non-rq
     drivers, from Gu Zheng.

   - Kill off artificial limiting of max sectors in a request from
     Christoph"

* 'for-3.19/core' of git://git.kernel.dk/linux-block: (26 commits)
  bio: modify __bio_add_page() to accept pages that don't start a new segment
  blk-mq: Fix uninitialized kobject at CPU hotplugging
  blktrace: don't let the sysfs interface remove trace from running list
  blk-mq: Use all available hardware queues
  blk-mq: Micro-optimize bt_get()
  blk-mq: Fix a race between bt_clear_tag() and bt_get()
  blk-mq: Avoid that __bt_get_word() wraps multiple times
  blk-mq: Fix a use-after-free
  blk-mq: prevent unmapped hw queue from being scheduled
  blk-mq: re-check for available tags after running the hardware queue
  blk-mq: fix hang in bt_get()
  blk-mq: move the kdump check to blk_mq_alloc_tag_set
  blk-mq: cleanup tag free handling
  blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map
  blk: introduce generic io stat accounting help function
  blk-mq: handle the single queue case in blk_mq_hctx_next_cpu
  genhd: check for int overflow in disk_expand_part_tbl()
  blk-mq: add blk_mq_free_hctx_request()
  blk-mq: export blk_mq_free_request()
  blk-mq: use get_cpu/put_cpu instead of preempt_disable/preempt_enable
  ...

bio: modify __bio_add_page() to accept pages that don't start a new segment

2014-12-11T16:11:52+00:00

The original behaviour is to refuse to add a new page if the maximum
number of segments has been reached, regardless of the fact the page we
are going to add can be merged into the last segment or not.

Unfortunately, when the system runs under heavy memory fragmentation
conditions, a driver may try to add multiple pages to the last segment.
The original code won't accept them and EBUSY will be reported to
userspace.

This patch modifies the function so it refuses to add a page only in case
the latter starts a new segment and the maximum number of segments has
already been reached.

The bug can be easily reproduced with the st driver:

1) set CONFIG_SCSI_MPT2SAS_MAX_SGE or CONFIG_SCSI_MPT3SAS_MAX_SGE  to 16
2) modprobe st buffer_kbs=1024
3) #dd if=/dev/zero of=/dev/st0 bs=1M count=10
   dd: error writing `/dev/st0': Device or resource busy

Signed-off-by: Maurizio Lombardi 
Signed-off-by: Ming Lei 
Cc: Jet Chen 
Cc: Tomas Henzl 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

Merge tag 'pm+acpi-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2014-12-11T05:17:00+00:00

Pull ACPI and power management updates from Rafael Wysocki:
"This time we have some more new material than we used to have during
the last couple of development cycles.

The most important part of it to me is the introduction of a unified
interface for accessing device properties provided by platform
firmware. It works with Device Trees and ACPI in a uniform way and
drivers using it need not worry about where the properties come from
as long as the platform firmware (either DT or ACPI) makes them
available. It covers both devices and "bare" device node objects
without struct device representation as that turns out to be necessary
in some cases. This has been in the works for quite a few months (and
development cycles) and has been approved by all of the relevant
maintainers.

On top of that, some drivers are switched over to the new interface
(at25, leds-gpio, gpio_keys_polled) and some additional changes are
made to the core GPIO subsystem to allow device drivers to manipulate
GPIOs in the "canonical" way on platforms that provide GPIO
information in their ACPI tables, but don't assign names to GPIO lines
(in which case the driver needs to do that on the basis of what it
knows about the device in question). That also has been approved by
the GPIO core maintainers and the rfkill driver is now going to use
it.

Second is support for hardware P-states in the intel_pstate driver.
It uses CPUID to detect whether or not the feature is supported by the
processor in which case it will be enabled by default. However, it
can be disabled entirely from the kernel command line if necessary.

Next is support for a platform firmware interface based on ACPI
operation regions used by the PMIC (Power Management Integrated
Circuit) chips on the Intel Baytrail-T and Baytrail-T-CR platforms.
That interface is used for manipulating power resources and for
thermal management: sensor temperature reporting, trip point setting
and so on.

Also the ACPI core is now going to support the _DEP configuration
information in a limited way. Basically, _DEP it supposed to reflect
off-the-hierarchy dependencies between devices which may be very
indirect, like when AML for one device accesses locations in an
operation region handled by another device's driver (usually, the
device depended on this way is a serial bus or GPIO controller). The
support added this time is sufficient to make the ACPI battery driver
work on Asus T100A, but it is general enough to be able to cover some
other use cases in the future.

Finally, we have a new cpufreq driver for the Loongson1B processor.

In addition to the above, there are fixes and cleanups all over the
place as usual and a traditional ACPICA update to a recent upstream
release.

As far as the fixes go, the ACPI LPSS (Low-power Subsystem) driver for
Intel platforms should be able to handle power management of the DMA
engine correctly, the cpufreq-dt driver should interact with the
thermal subsystem in a better way and the ACPI backlight driver should
handle some more corner cases, among other things.

On top of the ACPICA update there are fixes for race conditions in the
ACPICA's interrupt handling code which might lead to some random and
strange looking failures on some systems.

In the cleanups department the most visible part is the series of
commits targeted at getting rid of the CONFIG_PM_RUNTIME configuration
option. That was triggered by a discussion regarding the generic
power domains code during which we realized that trying to support
certain combinations of PM config options was painful and not really
worth it, because nobody would use them in production anyway. For
this reason, we decided to make CONFIG_PM_SLEEP select
CONFIG_PM_RUNTIME and that lead to the conclusion that the latter
became redundant and CONFIG_PM could be used instead of it. The
material here makes that replacement in a major part of the tree, but
there will be at least one more batch of that in the second part of
the merge window.

Specifics:

- Support for retrieving device properties information from ACPI _DSD
device configuration objects and a unified device properties
interface for device drivers (and subsystems) on top of that. As
stated above, this works with Device Trees and ACPI and allows
device drivers to be written in a platform firmware (DT or ACPI)
agnostic way. The at25, leds-gpio and gpio_keys_polled drivers are
now going to use this new interface and the GPIO subsystem is
additionally modified to allow device drivers to assign names to
GPIO resources returned by ACPI _CRS objects (in case _DSD is not
present or does not provide the expected data). The changes in
this set are mostly from Mika Westerberg, Rafael J Wysocki, Aaron
Lu, and Darren Hart with some fixes from others (Fabio Estevam,
Geert Uytterhoeven).

- Support for Hardware Managed Performance States (HWP) as described
in Volume 3, section 14.4, of the Intel SDM in the intel_pstate
driver. CPUID is used to detect whether or not the feature is
supported by the processor. If supported, it will be enabled
automatically unless the intel_pstate=no_hwp switch is present in
the kernel command line. From Dirk Brandewie.

- New Intel Broadwell-H ID for intel_pstate (Dirk Brandewie).

- Support for firmware interface based on ACPI operation regions used
by the PMIC chips on the Intel Baytrail-T and Baytrail-T-CR
platforms for power resource control and thermal management (Aaron
Lu).

- Limited support for retrieving off-the-hierarchy dependencies
between devices from ACPI _DEP device configuration objects and
deferred probing support for the ACPI battery driver based on the
_DEP information to make that driver work on Asus T100A (Lan
Tianyu).

- New cpufreq driver for the Loongson1B processor (Kelvin Cheung).

- ACPICA update to upstream revision 20141107 which only affects
tools (Bob Moore).

- Fixes for race conditions in the ACPICA's interrupt handling code
and in the ACPI code related to system suspend and resume (Lv Zheng
and Rafael J Wysocki).

- ACPI core fix for an RCU-related issue in the ioremap() regions
management code that slowed down significantly after CPUs had been
allowed to enter idle states even if they'd had RCU callbakcs
queued and triggered some problems in certain proprietary graphics
driver (and elsewhere). The fix replaces synchronize_rcu() in that
code with synchronize_rcu_expedited() which makes the issue go
away. From Konstantin Khlebnikov.

- ACPI LPSS (Low-Power Subsystem) driver fix to handle power
management of the DMA engine included into the LPSS correctly. The
problem is that the DMA engine doesn't have ACPI PM support of its
own and it simply is turned off when the last LPSS device having
ACPI PM support goes into D3cold. To work around that, the PM
domain used by the ACPI LPSS driver is redesigned so at least one
device with ACPI PM support will be on as long as the DMA engine is
in use. From Andy Shevchenko.

- ACPI backlight driver fix to avoid using it on "Win8-compatible"
systems where it doesn't work and where it was used by default by
mistake (Aaron Lu).

- Assorted minor ACPI core fixes and cleanups from Tomasz Nowicki,
Sudeep Holla, Huang Rui, Hanjun Guo, Fabian Frederick, and Ashwin
Chaugule (mostly related to the upcoming ARM64 support).

- Intel RAPL (Running Average Power Limit) power capping driver fixes
and improvements including new processor IDs (Jacob Pan).

- Generic power domains modification to power up domains after
attaching devices to them to meet the expectations of device
drivers and bus types assuming devices to be accessible at probe
time (Ulf Hansson).

- Preliminary support for controlling device clocks from the generic
power domains core code and modifications of the ARM/shmobile
platform to use that feature (Ulf Hansson).

- Assorted minor fixes and cleanups of the generic power domains core
code (Ulf Hansson, Geert Uytterhoeven).

- Assorted minor fixes and cleanups of the device clocks control code
in the PM core (Geert Uytterhoeven, Grygorii Strashko).

- Consolidation of device power management Kconfig options by making
CONFIG_PM_SLEEP select CONFIG_PM_RUNTIME and removing the latter
which is now redundant (Rafael J Wysocki and Kevin Hilman). That
is the first batch of the changes needed for this purpose.

- Core device runtime power management support code cleanup related
to the execution of callbacks (Andrzej Hajda).

- cpuidle ARM support improvements (Lorenzo Pieralisi).

- cpuidle cleanup related to the CPUIDLE_FLAG_TIME_VALID flag and a
new MAINTAINERS entry for ARM Exynos cpuidle (Daniel Lezcano and
Bartlomiej Zolnierkiewicz).

- New cpufreq driver callback (->ready) to be executed when the
cpufreq core is ready to use a given policy object and cpufreq-dt
driver modification to use that callback for cooling device
registration (Viresh Kumar).

- cpufreq core fixes and cleanups (Viresh Kumar, Vince Hsu, James
Geboski, Tomeu Vizoso).

- Assorted fixes and cleanups in the cpufreq-pcc, intel_pstate,
cpufreq-dt, pxa2xx cpufreq drivers (Lenny Szubowicz, Ethan Zhao,
Stefan Wahren, Petr Cvek).

- OPP (Operating Performance Points) framework modification to allow
OPPs to be removed too and update of a few cpufreq drivers
(cpufreq-dt, exynos5440, imx6q, cpufreq) to remove OPPs (added
during initialization) on driver removal (Viresh Kumar).

- Hibernation core fixes and cleanups (Tina Ruchandani and Markus
Elfring).

- PM Kconfig fix related to CPU power management (Pankaj Dubey).

- cpupower tool fix (Prarit Bhargava)"

* tag 'pm+acpi-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (120 commits)
i2c-omap / PM: Drop CONFIG_PM_RUNTIME from i2c-omap.c
dmaengine / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
tools: cpupower: fix return checks for sysfs_get_idlestate_count()
drivers: sh / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
e1000e / igb / PM: Eliminate CONFIG_PM_RUNTIME
MMC / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
MFD / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
misc / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
media / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
input / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
leds: leds-gpio: Fix multiple instances registration without 'label' property
iio / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
hsi / OMAP / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
i2c-hid / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
drm / exynos / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
gpio / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
hwrandom / exynos / PM: Use CONFIG_PM in #ifdef
block / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
USB / PM: Drop CONFIG_PM_RUNTIME from the USB core
PM: Merge the SET*_RUNTIME_PM_OPS() macros
...

blk-mq: Fix uninitialized kobject at CPU hotplugging

2014-12-10T15:57:31+00:00

When a CPU is hotplugged, the current blk-mq spews a warning like:

  kobject '(null)' (ffffe8ffffc8b5d8): tried to add an uninitialized object, something is seriously wrong.
  CPU: 1 PID: 1386 Comm: systemd-udevd Not tainted 3.18.0-rc7-2.g088d59b-default #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_171129-lamiak 04/01/2014
   0000000000000000 0000000000000002 ffffffff81605f07 ffffe8ffffc8b5d8
   ffffffff8132c7a0 ffff88023341d370 0000000000000020 ffff8800bb05bd58
   ffff8800bb05bd08 000000000000a0a0 000000003f441940 0000000000000007
  Call Trace:
   [] dump_trace+0x86/0x330
   [] show_stack_log_lvl+0x94/0x170
   [] show_stack+0x21/0x50
   [] dump_stack+0x41/0x51
   [] kobject_add+0xa0/0xb0
   [] blk_mq_register_hctx+0x91/0xb0
   [] blk_mq_sysfs_register+0x3e/0x60
   [] blk_mq_queue_reinit_notify+0xf8/0x190
   [] notifier_call_chain+0x4c/0x70
   [] cpu_notify+0x23/0x50
   [] _cpu_up+0x157/0x170
   [] cpu_up+0x89/0xb0
   [] cpu_subsys_online+0x35/0x80
   [] device_online+0x5d/0xa0
   [] online_store+0x75/0x80
   [] kernfs_fop_write+0xda/0x150
   [] vfs_write+0xb2/0x1f0
   [] SyS_write+0x42/0xb0
   [] system_call_fastpath+0x16/0x1b
   [<00007f0132fb24e0>] 0x7f0132fb24e0

This is indeed because of an uninitialized kobject for blk_mq_ctx.
The blk_mq_ctx kobjects are initialized in blk_mq_sysfs_init(), but it
goes loop over hctx_for_each_ctx(), i.e. it initializes only for
online CPUs.  Thus, when a CPU is hotplugged, the ctx for the newly
onlined CPU is registered without initialization.

This patch fixes the issue by initializing the all ctx kobjects
belonging to each queue.

Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=908794
Cc: 
Signed-off-by: Takashi Iwai 
Signed-off-by: Jens Axboe

blk-mq: Use all available hardware queues

2014-12-09T16:08:21+00:00

Suppose that a system has two CPU sockets, three cores per socket,
that it does not support hyperthreading and that four hardware
queues are provided by a block driver. With the current algorithm
this will lead to the following assignment of CPU cores to hardware
queues:

  HWQ 0: 0 1
  HWQ 1: 2 3
  HWQ 2: 4 5
  HWQ 3: (none)

This patch changes the queue assignment into:

  HWQ 0: 0 1
  HWQ 1: 2
  HWQ 2: 3 4
  HWQ 3: 5

In other words, this patch has the following three effects:
- All four hardware queues are used instead of only three.
- CPU cores are spread more evenly over hardware queues. For the
  above example the range of the number of CPU cores associated
  with a single HWQ is reduced from [0..2] to [1..2].
- If the number of HWQ's is a multiple of the number of CPU sockets
  it is now guaranteed that all CPU cores associated with a single
  HWQ reside on the same CPU socket.

Signed-off-by: Bart Van Assche 
Reviewed-by: Sagi Grimberg 
Cc: Jens Axboe 
Cc: Christoph Hellwig 
Cc: Ming Lei 
Cc: Alexander Gordeev 
Signed-off-by: Jens Axboe

blk-mq: Micro-optimize bt_get()

2014-12-09T16:07:28+00:00

Remove a superfluous finish_wait() call. Convert the two bt_wait_ptr()
calls into a single call.

Signed-off-by: Bart Van Assche 
Cc: Christoph Hellwig 
Cc: Robert Elliott 
Cc: Ming Lei 
Cc: Alexander Gordeev 
Signed-off-by: Jens Axboe

blk-mq: Fix a race between bt_clear_tag() and bt_get()

2014-12-09T16:07:16+00:00

What we need is the following two guarantees:
* Any thread that observes the effect of the test_and_set_bit() by
  __bt_get_word() also observes the preceding addition of 'current'
  to the appropriate wait list. This is guaranteed by the semantics
  of the spin_unlock() operation performed by prepare_and_wait().
  Hence the conversion of test_and_set_bit_lock() into
  test_and_set_bit().
* The wait lists are examined by bt_clear() after the tag bit has
  been cleared. clear_bit_unlock() guarantees that any thread that
  observes that the bit has been cleared also observes the store
  operations preceding clear_bit_unlock(). However,
  clear_bit_unlock() does not prevent that the wait lists are examined
  before that the tag bit is cleared. Hence the addition of a memory
  barrier between clear_bit() and the wait list examination.

Signed-off-by: Bart Van Assche 
Cc: Christoph Hellwig 
Cc: Robert Elliott 
Cc: Ming Lei 
Cc: Alexander Gordeev 
Cc:  # v3.13+
Signed-off-by: Jens Axboe

blk-mq: Avoid that __bt_get_word() wraps multiple times

2014-12-09T16:07:14+00:00

If __bt_get_word() is called with last_tag != 0, if the first
find_next_zero_bit() fails, if after wrap-around the
test_and_set_bit() call fails and find_next_zero_bit() succeeds,
if the next test_and_set_bit() call fails and subsequently
find_next_zero_bit() does not find a zero bit, then another
wrap-around will occur. Avoid this by introducing an additional
local variable.

Signed-off-by: Bart Van Assche 
Cc: Christoph Hellwig 
Cc: Robert Elliott 
Cc: Ming Lei 
Cc: Alexander Gordeev 
Cc:  # v3.13+
Signed-off-by: Jens Axboe

blk-mq: Fix a use-after-free

2014-12-09T16:07:13+00:00

blk-mq users are allowed to free the memory request_queue.tag_set
points at after blk_cleanup_queue() has finished but before
blk_release_queue() has started. This can happen e.g. in the SCSI
core. The SCSI core namely embeds the tag_set structure in a SCSI
host structure. The SCSI host structure is freed by
scsi_host_dev_release(). This function is called after
blk_cleanup_queue() finished but can be called before
blk_release_queue().

This means that it is not safe to access request_queue.tag_set from
inside blk_release_queue(). Hence remove the blk_sync_queue() call
from blk_release_queue(). This call is not necessary - outstanding
requests must have finished before blk_release_queue() is
called. Additionally, move the blk_mq_free_queue() call from
blk_release_queue() to blk_cleanup_queue() to avoid that struct
request_queue.tag_set gets accessed after it has been freed.

This patch avoids that the following kernel oops can be triggered
when deleting a SCSI host for which scsi-mq was enabled:

Call Trace:
 [] lock_acquire+0xc4/0x270
 [] mutex_lock_nested+0x61/0x380
 [] blk_mq_free_queue+0x30/0x180
 [] blk_release_queue+0x84/0xd0
 [] kobject_cleanup+0x7b/0x1a0
 [] kobject_put+0x30/0x70
 [] blk_put_queue+0x15/0x20
 [] disk_release+0x99/0xd0
 [] device_release+0x36/0xb0
 [] kobject_cleanup+0x7b/0x1a0
 [] kobject_put+0x30/0x70
 [] put_disk+0x1a/0x20
 [] __blkdev_put+0x135/0x1b0
 [] blkdev_put+0x50/0x160
 [] kill_block_super+0x44/0x70
 [] deactivate_locked_super+0x44/0x60
 [] deactivate_super+0x4e/0x70
 [] cleanup_mnt+0x43/0x90
 [] __cleanup_mnt+0x12/0x20
 [] task_work_run+0xac/0xe0
 [] do_notify_resume+0x61/0xa0
 [] int_signal+0x12/0x17

Signed-off-by: Bart Van Assche 
Cc: Christoph Hellwig 
Cc: Robert Elliott 
Cc: Ming Lei 
Cc: Alexander Gordeev 
Cc:  # v3.13+
Signed-off-by: Jens Axboe