queuing writes to the md thread means that all requests go through the
one processor which may not be able to keep up with very high request
rates.

So use the plugging infrastructure to submit all requests on unplug.
If a 'schedule' is needed, we fall back on the old approach of handing
the requests to the thread for it to handle.

This is nearly identical to a recent patch which provided similar
functionality to RAID1.
Signed-off-by: NNeilBrown <neilb@suse.de>

This makes md raid 10 support TRIM.

If one disk supports discard and another not, or one has
discard_zero_data and another not, there could be inconsistent between
data from such disks. But this should not matter, discarded data is
useless. This will add extra copy in rebuild though.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

This makes md raid 1 support TRIM.
If one disk supports discard and another not, or one has discard_zero_data and
another not, there could be inconsistent between data from such disks. But this
should not matter, discarded data is useless. This will add extra copy in rebuild
though.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

This makes md raid 0 support TRIM.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

This makes md linear support TRIM.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

According to the comment in linear_stop function
rcu_dereference in linear_start and linear_stop functions
occurs under reconfig_mutex. The patch represents this
agreement in code and prevents lockdep complaint.

Found by Linux Driver Verification project (linuxtesting.org)
Signed-off-by: NDenis Efremov <yefremov.denis@gmail.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

discard bio hasn't data attached. We hit a BUG_ON with such bio. This makes
bio_split works for such bio.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Replace 'while' with 'for' as suggested by Tejun Heo
Signed-off-by: NMaxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Useful helper to know the number of entries in scatterlist.
Signed-off-by: NMaxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We get the following export error on the include file:

usr/include/linux/fs.h:13: included file 'linux/percpu-rwsem.h' is not exported

Move the include inside the __KERNEL__ section.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

One more patch for this thing, fixing some typos in the documentation.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blkdev_mmap() isn't used outside of fs/block_dev.c, mark it as
static.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This avoids cache line bouncing when many processes lock the semaphore
for read.

New percpu lock implementation

The lock consists of an array of percpu unsigned integers, a boolean
variable and a mutex.

When we take the lock for read, we enter rcu read section, check for a
"locked" variable. If it is false, we increase a percpu counter on the
current cpu and exit the rcu section. If "locked" is true, we exit the
rcu section, take the mutex and drop it (this waits until a writer
finished) and retry.

Unlocking for read just decreases percpu variable. Note that we can
unlock on a difference cpu than where we locked, in this case the
counter underflows. The sum of all percpu counters represents the number
of processes that hold the lock for read.

When we need to lock for write, we take the mutex, set "locked" variable
to true and synchronize rcu. Since RCU has been synchronized, no
processes can create new read locks. We wait until the sum of percpu
counters is zero - when it is, there are no readers in the critical
section.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The kernel may crash when block size is changed and I/O is issued
simultaneously.

Because some subsystems (udev or lvm) may read any block device anytime,
the bug actually puts any code that changes a block device size in
jeopardy.

The crash can be reproduced if you place "msleep(1000)" to
blkdev_get_blocks just before "bh->b_size = max_blocks <<
inode->i_blkbits;".
Then, run "dd if=/dev/ram0 of=/dev/null bs=4k count=1 iflag=direct"
While it is waiting in msleep, run "blockdev --setbsz 2048 /dev/ram0"
You get a BUG.

The direct and non-direct I/O is written with the assumption that block
size does not change. It doesn't seem practical to fix these crashes
one-by-one there may be many crash possibilities when block size changes
at a certain place and it is impossible to find them all and verify the
code.

This patch introduces a new rw-lock bd_block_size_semaphore. The lock is
taken for read during I/O. It is taken for write when changing block
size. Consequently, block size can't be changed while I/O is being
submitted.

For asynchronous I/O, the patch only prevents block size change while
the I/O is being submitted. The block size can change when the I/O is in
progress or when the I/O is being finished. This is acceptable because
there are no accesses to block size when asynchronous I/O is being
finished.

The patch prevents block size changing while the device is mapped with
mmap.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

A queue newly allocated with blk_alloc_queue_node() has only
QUEUE_FLAG_BYPASS set.  For request-based drivers,
blk_init_allocated_queue() is called and q->queue_flags is overwritten
with QUEUE_FLAG_DEFAULT which doesn't include BYPASS even though the
initial bypass is still in effect.

In blk_init_allocated_queue(), or QUEUE_FLAG_DEFAULT to q->queue_flags
instead of overwriting.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Acked-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

block: lift the initial queue bypass mode on blk_register_queue() instead of blk_init_allocated_queue()

b82d4b19 ("blkcg: make request_queue bypassing on allocation") made
request_queues bypassed on allocation to avoid switching on and off
bypass mode on a queue being initialized.  Some drivers allocate and
then destroy a lot of queues without fully initializing them and
incurring bypass latency overhead on each of them could add upto
significant overhead.

Unfortunately, blk_init_allocated_queue() is never used by queues of
bio-based drivers, which means that all bio-based driver queues are in
bypass mode even after initialization and registration complete
successfully.

Due to the limited way request_queues are used by bio drivers, this
problem is hidden pretty well but it shows up when blk-throttle is
used in combination with a bio-based driver.  Trying to configure
(echoing to cgroupfs file) blk-throttle for a bio-based driver hangs
indefinitely in blkg_conf_prep() waiting for bypass mode to end.

This patch moves the initial blk_queue_bypass_end() call from
blk_init_allocated_queue() to blk_register_queue() which is called for
any userland-visible queues regardless of its type.

I believe this is correct because I don't think there is any block
driver which needs or wants working elevator and blk-cgroup on a queue
which isn't visible to userland.  If there are such users, we need a
different solution.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NJoseph Glanville <joseph.glanville@orionvm.com.au>
Cc: stable@vger.kernel.org
Acked-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Introduce a BLKZEROOUT ioctl which can be used to clear block ranges by
way of blkdev_issue_zeroout().
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If the device supports WRITE SAME, use that to optimize zeroing of
blocks. If the device does not support WRITE SAME or if the operation
fails, fall back to writing zeroes the old-fashioned way.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The WRITE SAME command supported on some SCSI devices allows the same
block to be efficiently replicated throughout a block range. Only a
single logical block is transferred from the host and the storage device
writes the same data to all blocks described by the I/O.

This patch implements support for WRITE SAME in the block layer. The
blkdev_issue_write_same() function can be used by filesystems and block
drivers to replicate a buffer across a block range. This can be used to
efficiently initialize software RAID devices, etc.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

 - blk_check_merge_flags() verifies that cmd_flags / bi_rw are
   compatible. This function is called for both req-req and req-bio
   merging.

 - blk_rq_get_max_sectors() and blk_queue_get_max_sectors() can be used
   to query the maximum sector count for a given request or queue. The
   calls will return the right value from the queue limits given the
   type of command (RW, discard, write same, etc.)
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Remove special-casing of non-rw fs style requests (discard). The nomerge
flags are consolidated in blk_types.h, and rq_mergeable() and
bio_mergeable() have been modified to use them.

bio_is_rw() is used in place of bio_has_data() a few places. This is
done to to distinguish true reads and writes from other fs type requests
that carry a payload (e.g. write same).
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Remove useless kfree() and clean up code related to the removal.

The semantic patch that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
position p1,p2;
expression x;
@@

if (x@p1 == NULL) { ... kfree@p2(x); ... return ...; }

@unchanged exists@
position r.p1,r.p2;
expression e <= r.x,x,e1;
iterator I;
statement S;
@@

if (x@p1 == NULL) { ... when != I(x,...) S
                        when != e = e1
                        when != e += e1
                        when != e -= e1
                        when != ++e
                        when != --e
                        when != e++
                        when != e--
                        when != &e
   kfree@p2(x); ... return ...; }

@ok depends on unchanged exists@
position any r.p1;
position r.p2;
expression x;
@@

... when != true x@p1 == NULL
kfree@p2(x);

@depends on !ok && unchanged@
position r.p2;
expression x;
@@

*kfree@p2(x);
// </smpl>
Signed-off-by: NPeter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Before call the blk_queue_congestion_threshold(),
the blk_queue_congestion_threshold() is already called at blk_queue_make_rquest().
Because this code is the duplicated, it has removed.
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Instead of using simple_strtoul which "converts" invalid numbers to 0,
use strict_strtoul and perform error checking to ensure that userspace
passes us a valid unsigned long. This addresses problems with functions
such as writev, which might want to write a trailing newline -- the
newline should rightfully be rejected, but the value preceeding it
should be preserved.

Fixes BZ#46981.
Signed-off-by: NDave Reisner <dreisner@archlinux.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Previously, there was bio_clone() but it only allocated from the fs bio
set; as a result various users were open coding it and using
__bio_clone().

This changes bio_clone() to become bio_clone_bioset(), and then we add
bio_clone() and bio_clone_kmalloc() as wrappers around it, making use of
the functionality the last patch adedd.

This will also help in a later patch changing how bio cloning works.
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
CC: Alasdair Kergon <agk@redhat.com>
CC: Boaz Harrosh <bharrosh@panasas.com>
CC: Jeff Garzik <jeff@garzik.org>
Acked-by: NJeff Garzik <jgarzik@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Previously, bio_kmalloc() and bio_alloc_bioset() behaved slightly
different because there was some almost-duplicated code - this fixes
some of that.

The important change is that previously bio_kmalloc() always set
bi_io_vec = bi_inline_vecs, even if nr_iovecs == 0 - unlike
bio_alloc_bioset(). This would cause bio_has_data() to return true; I
don't know if this resulted in any actual bugs but it was certainly
wrong.

bio_kmalloc() and bio_alloc_bioset() also have different arbitrary
limits on nr_iovecs - 1024 (UIO_MAXIOV) for bio_kmalloc(), 256
(BIO_MAX_PAGES) for bio_alloc_bioset(). This patch doesn't fix that, but
at least they're enforced closer together and hopefully they will be
fixed in a later patch.

This'll also help with some future cleanups - there are a fair number of
functions that allocate bios (e.g. bio_clone()), and now they don't have
to be duplicated for bio_alloc(), bio_alloc_bioset(), and bio_kmalloc().
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
v7: Re-add dropped comments, improv patch description
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that we've got generic code for freeing bios allocated from bio
pools, this isn't needed anymore.

This patch also makes bio_free() static, since without bi_destructor
there should be no need for it to be called anywhere else.

bio_free() is now only called from bio_put, so we can refactor those a
bit - move some code from bio_put() to bio_free() and kill the redundant
bio->bi_next = NULL.

v5: Switch to BIO_KMALLOC_POOL ((void *)~0), per Boaz
v6: BIO_KMALLOC_POOL now NULL, drop bio_free's EXPORT_SYMBOL
v7: No #define BIO_KMALLOC_POOL anymore
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This is prep work for killing bi_destructor - previously, pktcdvd had
its own pkt_bio_alloc which was basically duplication bio_kmalloc(),
necessitating its own bi_destructor implementation.

v5: Un-reorder some functions, to make the patch easier to review
Signed-off-by: NKent Overstreet <koverstreet@google.com>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Reusing bios is something that's been highly frowned upon in the past,
but driver code keeps doing it anyways. If it's going to happen anyways,
we should provide a generic method.

This'll help with getting rid of bi_destructor - drivers/block/pktcdvd.c
was open coding it, by doing a bio_init() and resetting bi_destructor.

This required reordering struct bio, but the block layer is not yet
nearly fast enough for any cacheline effects to matter here.

v5: Add a define BIO_RESET_BITS, to be very explicit about what parts of
bio->bi_flags are saved.
v6: Further commenting verbosity, per Tejun
v9: Add a function comment
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Previously, dm_rq_clone_bio_info needed to be freed by the bio's
destructor to avoid a memory leak in the blk_rq_prep_clone() error path.
This gets rid of a memory allocation and means we can kill
dm_rq_bio_destructor.

The _rq_bio_info_cache kmem cache is unused now and needs to be deleted,
but due to the way io_pool is used and overloaded this looks not quite
trivial so I'm leaving it for a later patch.

v6: Fix comment on struct dm_rq_clone_bio_info, per Tejun
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Alasdair Kergon <agk@redhat.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that bios keep track of where they were allocated from,
bio_integrity_alloc_bioset() becomes redundant.

Remove bio_integrity_alloc_bioset() and drop bio_set argument from the
related functions and make them use bio->bi_pool.
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

With the old code, when you allocate a bio from a bio pool you have to
implement your own destructor that knows how to find the bio pool the
bio was originally allocated from.

This adds a new field to struct bio (bi_pool) and changes
bio_alloc_bioset() to use it. This makes various bio destructors
unnecessary, so they're then deleted.

v6: Explain the temporary if statement in bio_put
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
CC: Alasdair Kergon <agk@redhat.com>
CC: Nicholas Bellinger <nab@linux-iscsi.org>
CC: Lars Ellenberg <lars.ellenberg@linbit.com>
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NNicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Pull ARM SoC bug fixes from Olof Johansson:
 "Mostly Renesas and Atmel bugfixes this time, targeting boot and build
  problems.  A couple of patches for gemini and kirkwood as well.  On a
  whole nothing very controversial."

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: gemini: fix the gemini build
  ARM: shmobile: armadillo800eva: enable rw rootfs mount
  ARM: Kirkwood: Fix 'SZ_1M' undeclared here for db88f6281-bp-setup.c
  ARM: shmobile: mackerel: fixup usb module order
  ARM: shmobile: armadillo800eva: fixup: sound card detection order
  ARM: shmobile: marzen: fixup smsc911x id for regulator
  ARM: at91/feature-removal-schedule: delay at91_mci removal
  ARM: mach-shmobile: armadillo800eva: Enable power button as wakeup source
  ARM: mach-shmobile: armadillo800eva: Fix GPIO buttons descriptions
  ARM: at91/dts: remove partial parameter in at91sam9g25ek.dts
  ARM: at91/clock: fix PLLA overclock warning
  ARM: at91: fix rtc-at91sam9 irq issue due to sparse irq support
  ARM: at91: fix system timer irq issue due to sparse irq support
  ARM: shmobile: sh73a0: fixup RELOC_BASE of intca_irq_pins_desc

Pull a hwmon fix from Guenter Roeck:
 "One patch, fixing DIV_ROUND_CLOSEST to support negative dividends.

  While the changes are not in the drivers/hwmon directory, the problem
  primarily affects hwmon drivers, and it makes sense to push the patch
  through the hwmon tree."

* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative dividends

Pull kbuild fixes from Michal Marek:
 "These are two fixes that should go into 3.6.  The link-vmlinux.sh one
  is obvious.

  The other one fixes make firmware_install with certain configurations,
  where a file in the toplevel firmware tree gets installed first, and
  $(INSTALL_FW_PATH)/$$(dir <file>) results in /lib/firmware/./, which
  confuses make 3.82 for some reason."

* 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
  firmware: fix directory creation rule matching with make 3.82
  link-vmlinux.sh: Fix stray "echo" in error message

Trivially triggerable, found by trinity:

  kernel BUG at mm/mempolicy.c:2546!
  Process trinity-child2 (pid: 23988, threadinfo ffff88010197e000, task ffff88007821a670)
  Call Trace:
    show_numa_map+0xd5/0x450
    show_pid_numa_map+0x13/0x20
    traverse+0xf2/0x230
    seq_read+0x34b/0x3e0
    vfs_read+0xac/0x180
    sys_pread64+0xa2/0xc0
    system_call_fastpath+0x1a/0x1f
  RIP: mpol_to_str+0x156/0x360

Cc: stable@vger.kernel.org
Signed-off-by: NDave Jones <davej@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull MMC fixes from Chris Ball:
 - a firmware bug on several Samsung MoviNAND eMMC models causes
   permanent corruption on the device when secure erase and secure trim
   requests are made, so we disable those requests on these eMMC devices.
 - atmel-mci: fix a hang with some SD cards by waiting for not-busy flag.
 - dw_mmc: low-power mode breaks SDIO interrupts; fix PIO error handling;
   fix handling of error interrupts.
 - mxs-mmc: fix deadlocks; fix compile error due to dma.h arch change.
 - omap: fix broken PIO mode causing memory corruption.
 - sdhci-esdhc: fix card detection.

* tag 'mmc-fixes-for-3.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc:
  mmc: omap: fix broken PIO mode
  mmc: card: Skip secure erase on MoviNAND; causes unrecoverable corruption.
  mmc: dw_mmc: Disable low power mode if SDIO interrupts are used
  mmc: dw_mmc: fix error handling in PIO mode
  mmc: dw_mmc: correct mishandling error interrupt
  mmc: dw_mmc: amend using error interrupt status
  mmc: atmel-mci: not busy flag has also to be used for read operations
  mmc: sdhci-esdhc: break out early if clock is 0
  mmc: mxs-mmc: fix deadlock caused by recursion loop
  mmc: mxs-mmc: fix deadlock in SDIO IRQ case
  mmc: bfin_sdh: fix dma_desc_array build error

Fix the following compile error on UML.

  arch/um/os-Linux/time.c: In function 'deliver_alarm':
  arch/um/os-Linux/time.c:117:3: error: too few arguments to function 'alarm_handler'
  arch/um/os-Linux/internal.h:1:6: note: declared here

The error was introduced by commit d3c1cfcd ("um: pass siginfo to guest
process") in 3.6-rc1.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: Martin Pärtel <martin.partel@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Allocate a structure not a pointer to it !
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull powerpc fixes from Benjamin Herrenschmidt:
 "Here are a few fixes for 3.6 that were piling up while I was away or
  busy (I was mostly MIA a week or two before San Diego).

  Some fixes from Anton fixing up issues with our relatively new DSCR
  control feature, and a few other fixes that are either regressions or
  bugs nasty enough to warrant not waiting."

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc: Don't use __put_user() in patch_instruction
  powerpc: Make sure IPI handlers see data written by IPI senders
  powerpc: Restore correct DSCR in context switch
  powerpc: Fix DSCR inheritance in copy_thread()
  powerpc: Keep thread.dscr and thread.dscr_inherit in sync
  powerpc: Update DSCR on all CPUs when writing sysfs dscr_default
  powerpc/powernv: Always go into nap mode when CPU is offline
  powerpc: Give hypervisor decrementer interrupts their own handler
  powerpc/vphn: Fix arch_update_cpu_topology() return value