Pull block fixes from Jens Axboe:

 - Mandate timespec64 for the io_uring timeout ABI (Arnd)

 - Set of NVMe changes via Sagi:
     - controller removal race fix from Balbir
     - quirk additions from Gabriel and Jian-Hong
     - nvme-pci power state save fix from Mario
     - Add 64bit user commands (for 64bit registers) from Marta
     - nvme-rdma/nvme-tcp fixes from Max, Mark and Me
     - Minor cleanups and nits from James, Dan and John

 - Two s390 dasd fixes (Jan, Stefan)

 - Have loop change block size in DIO mode (Martijn)

 - paride pg header ifdef guard (Masahiro)

 - Two blk-mq queue scheduler tweaks, fixing an ordering issue on zoned
   devices and suboptimal performance on others (Ming)

* tag 'for-linus-2019-10-03' of git://git.kernel.dk/linux-block: (22 commits)
  block: sed-opal: fix sparse warning: convert __be64 data
  block: sed-opal: fix sparse warning: obsolete array init.
  block: pg: add header include guard
  Revert "s390/dasd: Add discard support for ESE volumes"
  s390/dasd: Fix error handling during online processing
  io_uring: use __kernel_timespec in timeout ABI
  loop: change queue block size to match when using DIO
  blk-mq: apply normal plugging for HDD
  blk-mq: honor IO scheduler for multiqueue devices
  nvme-rdma: fix possible use-after-free in connect timeout
  nvme: Move ctrl sqsize to generic space
  nvme: Add ctrl attributes for queue_count and sqsize
  nvme: allow 64-bit results in passthru commands
  nvme: Add quirk for Kingston NVME SSD running FW E8FK11.T
  nvmet-tcp: remove superflous check on request sgl
  Added QUIRKs for ADATA XPG SX8200 Pro 512GB
  nvme-rdma: Fix max_hw_sectors calculation
  nvme: fix an error code in nvme_init_subsystem()
  nvme-pci: Save PCI state before putting drive into deepest state
  nvme-tcp: fix wrong stop condition in io_work
  ...

Today, put_compat_statfs64() disallows nearly any field value over
2^32 if f_bsize is only 32 bits, but that makes no sense.
compat_statfs64 is there for the explicit purpose of providing 64-bit
fields for f_files, f_ffree, etc.  And f_bsize is always only 32 bits.

As a result, 32-bit userspace gets -EOVERFLOW for i.e.  large file
counts even with -D_FILE_OFFSET_BITS=64 set.

In reality, only f_bsize and f_frsize can legitimately overflow
(fields like f_type and f_namelen should never be large), so test
only those fields.

This bug was discussed at length some time ago, and this is the proposal
Al suggested at https://lkml.org/lkml/2018/8/6/640.  It seemed to get
dropped amid the discussion of other related changes, but this
part seems obviously correct on its own, so I've picked it up and
sent it, for expediency.

Fixes: 64d2ab32 ("vfs: fix put_compat_statfs64() does not handle errors")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sparse warns about incorrect type when using __be64 data.
It is not being converted to CPU-endian but it should be.

Fixes these sparse warnings:

../block/sed-opal.c:375:20: warning: incorrect type in assignment (different base types)
../block/sed-opal.c:375:20:    expected unsigned long long [usertype] align
../block/sed-opal.c:375:20:    got restricted __be64 const [usertype] alignment_granularity
../block/sed-opal.c:376:25: warning: incorrect type in assignment (different base types)
../block/sed-opal.c:376:25:    expected unsigned long long [usertype] lowest_lba
../block/sed-opal.c:376:25:    got restricted __be64 const [usertype] lowest_aligned_lba

Fixes: 455a7b23 ("block: Add Sed-opal library")
Cc: Scott Bauer <scott.bauer@intel.com>
Cc: Rafael Antognolli <rafael.antognolli@intel.com>
Cc: linux-block@vger.kernel.org
Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Fix sparse warning: (missing '=')
../block/sed-opal.c:133:17: warning: obsolete array initializer, use C99 syntax

Fixes: ff91064e ("block: sed-opal: check size of shadow mbr")
Cc: linux-block@vger.kernel.org
Cc: Jonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>
Cc: David Kozub <zub@linux.fjfi.cvut.cz>
Reviewed-by: Scott Bauer <sbauer@plzdonthack.me>
Reviewed-by: Revanth Rajashekar <revanth.rajashekar@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull kgdb update from Daniel Thompson:
 "This is just a single patch adding a new reviewer for kgdb. New
  reviewers will be a big help so I decided to consider this to be a
  fix!

  I'm looking forward to working more closely with Doug"

* tag 'kgdb-5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux:
  MAINTAINERS: kgdb: Add myself as a reviewer for kgdb/kdb

I'm interested in kdb / kgdb and have sent various fixes over the
years.  I'd like to get CCed on patches so I can be aware of them and
also help review.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

Add a header include guard just in case.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Randy Dunlap reports on the sparse list that sparse warns about this
expression:

        of_irq->percpu ? free_percpu_irq(of_irq->irq, clkevt) :
                free_irq(of_irq->irq, clkevt);

and honestly, sparse is correct to warn.  The return type of
free_percpu_irq() is 'void', while free_irq() returns a 'const void *'
that is the devname argument passed in to the request_irq().

You can't mix a void type with a non-void types in a conditional
expression according to the C standard.  It so happens that gcc seems to
accept it - and the resulting type of the expression is void - but
there's really no reason for the kernel to have this kind of
non-standard expression with no real upside.

The natural way to write that expression is with an if-statement:

        if (of_irq->percpu)
                free_percpu_irq(of_irq->irq, clkevt);
        else
                free_irq(of_irq->irq, clkevt);

which is more legible anyway.

I'm not sure why that timer-of code seems to have this odd pattern.  It
does the same at allocation time, but at least there the types match,
and it makes sense as an expression.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull timer fix from Ingo Molnar:
 "Fix a broadcast-timer handling race that can result in spuriously and
  indefinitely delayed hrtimers and even RCU stalls if the system is
  otherwise quiet"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick: broadcast-hrtimer: Fix a race in bc_set_next

Pull membarrier fix from Ingo Molnar:
 "Fix broken locking within membarrier_private_expedited()"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  membarrier: Fix RCU locking bug caused by faulty merge

Pull erofs fixes from Gao Xiang:
 "Three patches to address regressions due to recent cleanups, mainly
  found by stress test on latest mainline kernel (no more regression out
  compared with older kernels for more than a week)

  One additional patch updates sub-entries in MAINTAINERS.

  Summary:

   - Fix error handling in erofs_read_superblock

   - Fix locking in erofs_get_meta_page

   - Fix inplace behavior due to decompression frontend cleanup

   - Update sub-entries in MAINTAINERS in order to better blame"

* tag 'erofs-for-5.4-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: fix mis-inplace determination related with noio chain
  erofs: fix erofs_get_meta_page locking due to a cleanup
  MAINTAINERS: erofs: complete sub-entries for erofs
  erofs: fix return value check in erofs_read_superblock()

On Tue, Oct 01, 2019 at 10:14:40AM -0700, Linus Torvalds wrote:
> The previous state of the file didn't have that 0xa at the end, so you get that
>
>
>   -EXPORT_SYMBOL_GPL(add_bootloader_randomness);
>   \ No newline at end of file
>   +EXPORT_SYMBOL_GPL(add_bootloader_randomness);
>
> which is "the '-' line doesn't have a newline, the '+' line does" marker.

Aaha, that makes total sense, thanks for explaining. Oh well, let's fix
it then so that people don't scratch heads like me.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The following commit:

  227a4aad ("sched/membarrier: Fix p->mm->membarrier_state racy load")

got fat fingered by me when merging it with other patches. It meant to move
the RCU section out of the for loop but ended up doing it partially, leaving
a superfluous rcu_read_lock() inside, causing havok.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-tip-commits@vger.kernel.org
Fixes: 227a4aad ("sched/membarrier: Fix p->mm->membarrier_state racy load")
Link: https://lkml.kernel.org/r/20191001085033.GP4519@hirez.programming.kicks-ass.netSigned-off-by: Ingo Molnar <mingo@kernel.org>

This reverts commit 7e64db15.

The thin provisioning feature introduces an IOCTL and the discard support
to allow userspace tools and filesystems to release unused and previously
allocated space respectively.

During some internal performance improvements and further tests, the
release of allocated space revealed some issues that may lead to data
corruption in some configurations when filesystems are mounted with
discard support enabled.

While we're working on a fix and trying to clarify the situation,
this commit reverts the discard support for ESE volumes to prevent
potential data corruption.

Cc: <stable@vger.kernel.org> # 5.3
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

It is possible that the CCW commands for reading volume and extent pool
information are not supported, either by the storage server (for
dedicated DASDs) or by z/VM (for virtual devices, such as MDISKs).

As a command reject will occur in such a case, the current error
handling leads to a failing online processing and thus the DASD can't be
used at all.

Since the data being read is not essential for an fully operational
DASD, the error handling can be removed. Information about the failing
command is sent to the s390dbf debug feature.

Fixes: c729696b ("s390/dasd: Recognise data for ESE volumes")
Cc: <stable@vger.kernel.org> # 5.3
Reported-by: Frank Heimes <frank.heimes@canonical.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

All system calls use struct __kernel_timespec instead of the old struct
timespec, but this one was just added with the old-style ABI. Change it
now to enforce the use of __kernel_timespec, avoiding ABI confusion and
the need for compat handlers on 32-bit architectures.

Any user space caller will have to use __kernel_timespec now, but this
is unambiguous and works for any C library regardless of the time_t
definition. A nicer way to specify the timeout would have been a less
ambiguous 64-bit nanosecond value, but I suppose it's too late now to
change that as this would impact both 32-bit and 64-bit users.

Fixes: 5262f567 ("io_uring: IORING_OP_TIMEOUT support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The loop driver assumes that if the passed in fd is opened with
O_DIRECT, the caller wants to use direct I/O on the loop device.
However, if the underlying block device has a different block size than
the loop block queue, direct I/O can't be enabled. Instead of requiring
userspace to manually change the blocksize and re-enable direct I/O,
just change the queue block sizes to match, as well as the io_min size.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martijn Coenen <maco@android.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Fix a recent cleanup patch. noio (bypass) chain is
handled asynchronously against submit chain, therefore
inplace I/O or pagevec cannot be applied to such pages.
Add detailed comment for this as well.

Fixes: 97e86a85 ("staging: erofs: tidy up decompression frontend")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190922100434.229340-1-gaoxiang25@huawei.comSigned-off-by: Gao Xiang <gaoxiang25@huawei.com>

After doing more drop_caches stress test on
our products, I found the mistake introduced by
a very recent cleanup [1].

The current rule is that "erofs_get_meta_page"
should be returned with page locked (although
it's mostly unnecessary for read-only fs after
pages are PG_uptodate), but a fix should be
done for this.

[1] https://lore.kernel.org/r/20190904020912.63925-26-gaoxiang25@huawei.com
Fixes: 618f40ea ("erofs: use read_cache_page_gfp for erofs_get_meta_page")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190921184355.149928-1-gaoxiang25@huawei.comSigned-off-by: Gao Xiang <gaoxiang25@huawei.com>

Add a formal git tree and missing files for erofs
after moving out of staging for everyone to blame
in order for better improvement.
Acked-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190919062838.106423-1-gaoxiang25@huawei.comSigned-off-by: Gao Xiang <gaoxiang25@huawei.com>

In case of error, the function read_mapping_page() returns
ERR_PTR() not NULL. The NULL test in the return value check
should be replaced with IS_ERR().

Fixes: fe7c2423 ("erofs: use read_mapping_page instead of sb_bread")
Reviewed-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20190918083033.47780-1-weiyongjun1@huawei.comSigned-off-by: Gao Xiang <gaoxiang25@huawei.com>

Pull btrfs fixes from David Sterba:
 "A bunch of fixes that accumulated in recent weeks, mostly material for
  stable.

  Summary:

   - fix for regression from 5.3 that prevents to use balance convert
     with single profile

   - qgroup fixes: rescan race, accounting leak with multiple writers,
     potential leak after io failure recovery

   - fix for use after free in relocation (reported by KASAN)

   - other error handling fixups"

* tag 'for-5.4-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: qgroup: Fix reserved data space leak if we have multiple reserve calls
  btrfs: qgroup: Fix the wrong target io_tree when freeing reserved data space
  btrfs: Fix a regression which we can't convert to SINGLE profile
  btrfs: relocation: fix use-after-free on dead relocation roots
  Btrfs: fix race setting up and completing qgroup rescan workers
  Btrfs: fix missing error return if writeback for extent buffer never started
  btrfs: adjust dirty_metadata_bytes after writeback failure of extent buffer
  Btrfs: fix selftests failure due to uninitialized i_mode in test inodes

Pull csky updates from Guo Ren:
 "This round of csky subsystem just some fixups:

   - Fix mb() synchronization problem

   - Fix dma_alloc_coherent with PAGE_SO attribute

   - Fix cache_op failed when cross memory ZONEs

   - Optimize arch_sync_dma_for_cpu/device with dma_inv_range

   - Fix ioremap function losing

   - Fix arch_get_unmapped_area() implementation

   - Fix defer cache flush for 610

   - Support kernel non-aligned access

   - Fix 610 vipt cache flush mechanism

   - Fix add zero_fp fixup perf backtrace panic

   - Move static keyword to the front of declaration

   - Fix csky_pmu.max_period assignment

   - Use generic free_initrd_mem()

   - entry: Remove unneeded need_resched() loop"

* tag 'csky-for-linus-5.4-rc1' of git://github.com/c-sky/csky-linux:
  csky: Move static keyword to the front of declaration
  csky: entry: Remove unneeded need_resched() loop
  csky: Fixup csky_pmu.max_period assignment
  csky: Fixup add zero_fp fixup perf backtrace panic
  csky: Use generic free_initrd_mem()
  csky: Fixup 610 vipt cache flush mechanism
  csky: Support kernel non-aligned access
  csky: Fixup defer cache flush for 610
  csky: Fixup arch_get_unmapped_area() implementation
  csky: Fixup ioremap function losing
  csky: Optimize arch_sync_dma_for_cpu/device with dma_inv_range
  csky/dma: Fixup cache_op failed when cross memory ZONEs
  csky: Fixup dma_alloc_coherent with PAGE_SO attribute
  csky: Fixup mb() synchronization problem

Pull ARM SoC fixes from Olof Johansson:
 "A few fixes that have trickled in through the merge window:

   - Video fixes for OMAP due to panel-dpi driver removal

   - Clock fixes for OMAP that broke no-idle quirks + nfsroot on DRA7

   - Fixing arch version on ASpeed ast2500

   - Two fixes for reset handling on ARM SCMI"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
  ARM: aspeed: ast2500 is ARMv6K
  reset: reset-scmi: add missing handle initialisation
  firmware: arm_scmi: reset: fix reset_state assignment in scmi_domain_reset
  bus: ti-sysc: Remove unpaired sysc_clkdm_deny_idle()
  ARM: dts: logicpd-som-lv: Fix i2c2 and i2c3 Pin mux
  ARM: dts: am3517-evm: Fix missing video
  ARM: dts: logicpd-torpedo-baseboard: Fix missing video
  ARM: omap2plus_defconfig: Fix missing video
  bus: ti-sysc: Fix handling of invalid clocks
  bus: ti-sysc: Fix clock handling for no-idle quirks

Pull tracing fixes from Steven Rostedt:
 "A few more tracing fixes:

   - Fix a buffer overflow by checking nr_args correctly in probes

   - Fix a warning that is reported by clang

   - Fix a possible memory leak in error path of filter processing

   - Fix the selftest that checks for failures, but wasn't failing

   - Minor clean up on call site output of a memory trace event"

* tag 'trace-v5.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  selftests/ftrace: Fix same probe error test
  mm, tracing: Print symbol name for call_site in trace events
  tracing: Have error path in predicate_parse() free its allocated memory
  tracing: Fix clang -Wint-in-bool-context warnings in IF_ASSIGN macro
  tracing/probe: Fix to check the difference of nr_args before adding probe

Pull more MMC updates from Ulf Hansson:
 "A couple more updates/fixes for MMC:

   - sdhci-pci: Add Genesys Logic GL975x support

   - sdhci-tegra: Recover loss in throughput for DMA

   - sdhci-of-esdhc: Fix DMA bug"

* tag 'mmc-v5.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: host: sdhci-pci: Add Genesys Logic GL975x support
  mmc: tegra: Implement ->set_dma_mask()
  mmc: sdhci: Let drivers define their DMA mask
  mmc: sdhci-of-esdhc: set DMA snooping based on DMA coherence
  mmc: sdhci: improve ADMA error reporting

Move the static keyword to the front of declaration of
csky_pmu_of_device_ids, and resolve the following compiler
warning that can be seen when building with warnings
enabled (W=1):

arch/csky/kernel/perf_event.c:1340:1: warning:
  ‘static’ is not at beginning of declaration [-Wold-style-declaration]
Signed-off-by: Krzysztof Wilczynski <kw@linux.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

Since the enabling and disabling of IRQs within preempt_schedule_irq()
is contained in a need_resched() loop, we don't need the outer arch
code loop.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

Pull Documentation/process update from Greg KH:
 "Here are two small Documentation/process/embargoed-hardware-issues.rst
  file updates that missed my previous char/misc pull request.

  The first one adds an Intel representative for the process, and the
  second one cleans up the text a bit more when it comes to how the
  disclosure rules work, as it was a bit confusing to some companies"

* tag 'char-misc-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  Documentation/process: Clarify disclosure rules
  Documentation/process: Volunteer as the ambassador for Intel

Pull more vfs updates from Al Viro:
 "A couple of misc patches"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  afs dynroot: switch to simple_dir_operations
  fs/handle.c - fix up kerneldoc

Pull more cifs updates from Steve French:
 "Fixes from the recent SMB3 Test events and Storage Developer
  Conference (held the last two weeks).

  Here are nine smb3 patches including an important patch for debugging
  traces with wireshark, with three patches marked for stable.

  Additional fixes from last week to better handle some newly discovered
  reparse points, and a fix the create/mkdir path for setting the mode
  more atomically (in SMB3 Create security descriptor context), and one
  for path name processing are still being tested so are not included
  here"

* tag '5.4-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  CIFS: Fix oplock handling for SMB 2.1+ protocols
  smb3: missing ACL related flags
  smb3: pass mode bits into create calls
  smb3: Add missing reparse tags
  CIFS: fix max ea value size
  fs/cifs/sess.c: Remove set but not used variable 'capabilities'
  fs/cifs/smb2pdu.c: Make SMB2_notify_init static
  smb3: fix leak in "open on server" perf counter
  smb3: allow decryption keys to be dumped by admin for debugging

The csky_pmu.max_period has type u64, and BIT() can only return
32 bits unsigned long on C-SKY. The initialization for max_period
will be incorrect when count_width is bigger than 32.

Use BIT_ULL()
Signed-off-by: Mao Han <han_mao@c-sky.com>
Signed-off-by: Guo Ren <ren_guo@c-sky.com>

We need set fp zero to let backtrace know the end. The patch fixup perf
callchain panic problem, because backtrace didn't know what is the end
of fp.
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reported-by: Mao Han <han_mao@c-sky.com>

The csky implementation of free_initrd_mem() is an open-coded version of
free_reserved_area() without poisoning.

Remove it and make csky use the generic version of free_initrd_mem().
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

Merge active entropy generation updates.

This is admittedly partly "for discussion".  We need to have a way
forward for the boot time deadlocks where user space ends up waiting for
more entropy, but no entropy is forthcoming because the system is
entirely idle just waiting for something to happen.

While this was triggered by what is arguably a user space bug with
GDM/gnome-session asking for secure randomness during early boot, when
they didn't even need any such truly secure thing, the issue ends up
being that our "getrandom()" interface is prone to that kind of
confusion, because people don't think very hard about whether they want
to block for sufficient amounts of entropy.

The approach here-in is to decide to not just passively wait for entropy
to happen, but to start actively collecting it if it is missing.  This
is not necessarily always possible, but if the architecture has a CPU
cycle counter, there is a fair amount of noise in the exact timings of
reasonably complex loads.

We may end up tweaking the load and the entropy estimates, but this
should be at least a reasonable starting point.

As part of this, we also revert the revert of the ext4 IO pattern
improvement that ended up triggering the reported lack of external
entropy.

* getrandom() active entropy waiting:
  Revert "Revert "ext4: make __ext4_get_inode_loc plug""
  random: try to actively add entropy rather than passively wait for it

This reverts commit 72dbcf72.

Instead of waiting forever for entropy that may just not happen, we now
try to actively generate entropy when required, and are thus hopefully
avoiding the problem that caused the nice ext4 IO pattern fix to be
reverted.

So revert the revert.

Cc: Ahmed S. Darwish <darwish.07@gmail.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Alexander E. Patrakov <patrakov@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For 5.3 we had to revert a nice ext4 IO pattern improvement, because it
caused a bootup regression due to lack of entropy at bootup together
with arguably broken user space that was asking for secure random
numbers when it really didn't need to.

See commit 72dbcf72 (Revert "ext4: make __ext4_get_inode_loc plug").

This aims to solve the issue by actively generating entropy noise using
the CPU cycle counter when waiting for the random number generator to
initialize.  This only works when you have a high-frequency time stamp
counter available, but that's the case on all modern x86 CPU's, and on
most other modern CPU's too.

What we do is to generate jitter entropy from the CPU cycle counter
under a somewhat complex load: calling the scheduler while also
guaranteeing a certain amount of timing noise by also triggering a
timer.

I'm sure we can tweak this, and that people will want to look at other
alternatives, but there's been a number of papers written on jitter
entropy, and this should really be fairly conservative by crediting one
bit of entropy for every timer-induced jump in the cycle counter.  Not
because the timer itself would be all that unpredictable, but because
the interaction between the timer and the loop is going to be.

Even if (and perhaps particularly if) the timer actually happens on
another CPU, the cacheline interaction between the loop that reads the
cycle counter and the timer itself firing is going to add perturbations
to the cycle counter values that get mixed into the entropy pool.

As Thomas pointed out, with a modern out-of-order CPU, even quite simple
loops show a fair amount of hard-to-predict timing variability even in
the absense of external interrupts.  But this tries to take that further
by actually having a fairly complex interaction.

This is not going to solve the entropy issue for architectures that have
no CPU cycle counter, but it's not clear how (and if) that is solvable,
and the hardware in question is largely starting to be irrelevant.  And
by doing this we can at least avoid some of the even more contentious
approaches (like making the entropy waiting time out in order to avoid
the possibly unbounded waiting).

Cc: Ahmed Darwish <darwish.07@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Nicholas Mc Guire <hofrat@opentech.at>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Alexander E. Patrakov <patrakov@gmail.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'fixes-5.4-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into arm/fixes

Fixes for omap variants

Few fixes for ti-sysc interconnect target module driver for no-idle
quirks that caused nfsroot to fail on some dra7 boards.

And let's fixes to get LCD working again for logicpd board that got
broken a while back with removal of panel-dpi driver. We need to now
use generic CONFIG_DRM_PANEL_SIMPLE instead.

* tag 'fixes-5.4-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  bus: ti-sysc: Remove unpaired sysc_clkdm_deny_idle()
  ARM: dts: logicpd-som-lv: Fix i2c2 and i2c3 Pin mux
  ARM: dts: am3517-evm: Fix missing video
  ARM: dts: logicpd-torpedo-baseboard: Fix missing video
  ARM: omap2plus_defconfig: Fix missing video
  bus: ti-sysc: Fix handling of invalid clocks
  bus: ti-sysc: Fix clock handling for no-idle quirks

Link: https://lore.kernel.org/r/pull-1568819401-72461@atomide.comSigned-off-by: Olof Johansson <olof@lixom.net>

Merge tag 'scmi-fixes-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into arm/fixes

ARM SCMI fixes for v5.4

Couple of fixes: one in scmi reset driver initialising missed scmi handle
and an other in scmi reset API implementation fixing the assignment of
reset state

* tag 'scmi-fixes-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  reset: reset-scmi: add missing handle initialisation
  firmware: arm_scmi: reset: fix reset_state assignment in scmi_domain_reset

Link: https://lore.kernel.org/r/20190918142139.GA4370@bogusSigned-off-by: Olof Johansson <olof@lixom.net>