cpuset: convert callback_mutex to a spinlock

The callback_mutex is only used to synchronize reads/updates of cpusets'
flags and cpu/node masks. These operations should always proceed fast so
there's no reason why we can't use a spinlock instead of the mutex.

Converting the callback_mutex into a spinlock will let us call
cpuset_zone_allowed_softwall from atomic context. This, in turn, makes
it possible to simplify the code by merging the hardwall and asoftwall
checks into the same function, which is the business of the next patch.

Suggested-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset: simplify cpuset_node_allowed API

Current cpuset API for checking if a zone/node is allowed to allocate
from looks rather awkward. We have hardwall and softwall versions of
cpuset_node_allowed with the softwall version doing literally the same
as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags.
If it isn't, the softwall version may check the given node against the
enclosing hardwall cpuset, which it needs to take the callback lock to
do.

Such a distinction was introduced by commit 02a0e53d8227 ("cpuset:
rework cpuset_zone_allowed api"). Before, we had the only version with
the __GFP_HARDWALL flag determining its behavior. The purpose of the
commit was to avoid sleep-in-atomic bugs when someone would mistakenly
call the function without the __GFP_HARDWALL flag for an atomic
allocation. The suffixes introduced were intended to make the callers
think before using the function.

However, since the callback lock was converted from mutex to spinlock by
the previous patch, the softwall check function cannot sleep, and these
precautions are no longer necessary.

So let's simplify the API back to the single check.

Suggested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset: lock vs unlock typo

This will deadlock instead of unlocking.

Fixes: f73eae8d8384 ('cpuset: simplify cpuset_node_allowed API')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
percpu: off by one in BUG_ON()

The unit_map[] array has "nr_cpu_ids" number of elements.  It's
allocated a few lines earlier in the function.  So this test should be
>= instead of >.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
percpu: Convert remaining __get_cpu_var uses in 3.18-rcX

During the 3.18 merge period additional __get_cpu_var uses were
added. The patch converts these to this_cpu_ptr().

Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
libsas: use ata_dev_classify()

Use the ata device class from libata in libsas instead of checking
the supported command set and switch to using ata_dev_classify()
instead of our own method.

Cc: Tejun Heo <tj@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
libata: Implement ATA_DEV_ZAC

Add new ATA device type for ZAC devices.

Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
libata-scsi: Update SATL for ZAC drives

ZAC (zoned-access command) drives translate into ZBC (Zoned block
command) device type for SCSI. So implement the correct mappings
into libata-scsi and update the SCSI command set versions.

Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
ahci_sunxi: Make AHCI_HFLAG_NO_PMP flag configurable with a module option

The use of the AHCI_HFLAG_NO_PMP flag is something which we inherited from
the Allwinner android kernel sources, and I've always wanted to test if this
is really necessary.

So recently I've bought a sata port multiplexer, and I've given this a test
spin on both A10 and A20 devices, and it seems to work fine:

[    2.154456] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    2.161092] ata1.15: Port Multiplier 1.2, 0x197b:0x0325 r0, 5 ports, feat 0x5/0xf
[    2.175511] ata1.00: hard resetting link
[    2.524929] ata1.00: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
[    2.531430] ata1.01: hard resetting link
[    2.974465] ata1.01: link resume succeeded after 1 retries
[    3.094932] ata1.01: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[    3.101431] ata1.02: hard resetting link
[    4.174466] ata1.02: failed to resume link (SControl 0)
[    4.180065] ata1.02: SATA link down (SStatus 0 SControl 0)
(and the same for links 3 and 4)

Once the NO_PMP flag is removed it correctly sees the 2 disks which I've
attached, and I can mount and use them just fine.

Unfortunately when I then directly attached a disk to the sata port on the
sunxi SoC, and booted a kernel without the AHCI_HFLAG_NO_PMP flag, it would
not recognize that disk.

It turns out that the sata controller in the sunxi SoCs fails to handle
soft-resets issued to directly attached disks, and when pmp support is
enabled the kernel will always issue a soft-reset.

So add a module parameter to enable pmp usage, and default this to off, so
that directly attached disks keep working normally.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
sata_rcar: Add clocks to sata_rcar bindings

Now that the clocks are available in the R-Car Gen2 DT,
add clocks property description to the sata_rcar bindings.
The clocks have been tested on r8a7791 so we use that
as an example of the R-Car SATA node.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
[geert: Reworded clocks property]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Tejun Heo <tj@kernel.org>
sata_rcar: Document deprecated "renesas,rcar-sata"

Commit e67adb4e669db834 ("sata_rcar: Add R-Car Gen2 SATA PHY support")
deprecated "renesas,rcar-sata" in favor of "renesas,sata-r8a7779", but
the deprecated value was never documented in the binding documentation,
while it is still in active use.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask()

cgroup_refresh_child_subsys_mask() calculates and updates the
effective @cgrp->child_subsys_maks according to the current
@cgrp->subtree_control.  Separate out the calculation part into
cgroup_calc_child_subsys_mask().  This will be used to fix a bug in
the async css offline wait logic.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write()

Make cgroup_subtree_control_write() first calculate new
subtree_control (new_sc), child_subsys_mask (new_ss) and
css_enable/disable masks before applying them to the cgroup.  Also,
store the original subtree_control (old_sc) and child_subsys_mask
(old_ss) and use them to restore the orignal state after failure.

This patch shouldn't cause any behavior changes.  This prepares for a
fix for a bug in the async css offline wait logic.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
cgroup: fix the async css offline wait logic in cgroup_subtree_control_write()

When a subsystem is offlined, its entry on @cgrp->subsys[] is cleared
asynchronously.  If cgroup_subtree_control_write() is requested to
enable the subsystem again before the entry is cleared, it has to wait
for the previous offlining to finish and clear the @cgrp->subsys[]
entry before trying to enable the subsystem again.

This is currently done while verifying the input enable / disable
parameters.  This used to be correct but f63070d350e3 ("cgroup: make
interface files visible iff enabled on cgroup->subtree_control")
breaks it.  The commit is one of the commits implementing subsystem
dependency.

Through subsystem dependency, some subsystems may be enabled and
disabled implicitly in addition to the explicitly requested ones.  The
actual subsystems to be enabled and disabled are determined during
@css_enable/disable calculation.  The current offline wait logic skips
the ones which are already implicitly enabled and then waits for
subsystems in @enable; however, this misses the subsystems which may
be implicitly enabled through dependency from @enable.  If such
implicitly subsystem hasn't yet finished offlining yet, the function
ends up trying to create a css when its @cgrp->subsys[] slot is
already occupied triggering BUG_ON() in init_and_link_css().

Fix it by moving the wait logic after @css_enable is calculated and
waiting for all the subsystems in @css_enable.  This fixes the above
bug as the mask contains all subsystems which are to be enabled
including the ones enabled through dependencies.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control")
Acked-by: Zefan Li <lizefan@huawei.com>
cgroup: add cgroup_subsys->css_released()

Add a new cgroup subsys callback css_released().  This is called when
the reference count of the css (cgroup_subsys_state) reaches zero
before RCU scheduling free.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
cgroup: add cgroup_subsys->css_e_css_changed()

Add a new cgroup_subsys operatoin ->css_e_css_changed().  This is
invoked if any of the effective csses seen from the css's cgroup may
have changed.  This will be used to implement cgroup writeback
support.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
cgroup: implement cgroup_get_e_css()

Implement cgroup_get_e_css() which finds and gets the effective css
for the specified cgroup and subsystem combination.  This function
always returns a valid pinned css.  This will be used by cgroup
writeback support.

While at it, add comment to cgroup_e_css() to explain why that
function is different from cgroup_get_e_css() and has to test
cgrp->child_subsys_mask instead of cgroup_css(cgrp, ss).

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Merge branch 'master' into for-3.19

Pull in to receive 54ef6df3f3f1 ("rcu: Provide counterpart to
rcu_dereference() for non-RCU situations").

Signed-off-by: Tejun Heo <tj@kernel.org>
percpu: Replace smp_read_barrier_depends() with lockless_dereference()

Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
workqueue: cosmetic update in rescuer_thread()

rescuer_thread() caches &rescuer->scheduled in a local variable
scheduled for convenience.  There's one WARN_ON_ONCE() which was using
&rescuer->scheduled directly.  Replace it with the local variable.

This patch causes no functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>