The Keystone 2 supports DT-boot only, as result dma_mask will be
always configured properly from DT -
of_platform_device_create_pdata()->of_dma_configure(). More over,
dwc3-keystone.c can be built as module and in this case it's unsafe to
assign local variable as dma_mask.

Hence, remove dma_mask configuration code.

Cc: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Since commit 7ace8fc8 ("usb: gadget: udc: core: Fix argument of
dma_map_single for IOMMU") it is not necessary to configure DMA for
usb_gadget device manually, because all DMA operation are performed
using parent/controller device.

Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

BXT-M is a Intel Broxton SoC based platform with unique PCI ID.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

This patch fixes an issue that usbhsg_queue_done() may cause kernel
panic when dma callback is running and usb_ep_disable() is called
by interrupt handler. (Especially, we can reproduce this issue using
g_audio with usb-dmac driver.)

For example of a flow:
 usbhsf_dma_complete (on tasklet)
  --> usbhsf_pkt_handler (on tasklet)
   --> usbhsg_queue_done (on tasklet)
    *** interrupt happened and usb_ep_disable() is called ***
    --> usbhsg_queue_pop (on tasklet)
     Then, oops happened.

Fixes: e73a9891 ("usb: renesas_usbhs: add DMAEngine support")
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

The host/device mode set with dr_mode should be kept all the time,
not being changed to OTG in gadget setup (by overriding CFGUSB_FORCEDEVMODE
and CFGUSB_FORCEHOSTMODE bits).
Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Przemek Rudy <prudy1@o2.pl>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

We added some new locking here, but missed an error path where we need
to unlock.

Fixes: 9acdf4df ('usb: gadget: f_midi: added spinlock on transmit function')
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

This patch adds a code to surely disable TX IRQ of the pipe before
starting TX DMAC transfer. Otherwise, a lot of unnecessary TX IRQs
may happen in rare cases when DMAC is used.

Fixes: e73a9891 ("usb: renesas_usbhs: add DMAEngine support")
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

When unexpected situation happened (e.g. tx/rx irq happened while
DMAC is used), the usbhsf_pkt_handler() was possible to cause NULL
pointer dereference like the followings:

Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 80000007 [#1] SMP ARM
Modules linked in: usb_f_acm u_serial g_serial libcomposite
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.5.0-rc6-00842-gac57066-dirty #63
Hardware name: Generic R8A7790 (Flattened Device Tree)
task: c0729c00 ti: c0724000 task.ti: c0724000
PC is at 0x0
LR is at usbhsf_pkt_handler+0xac/0x118
pc : [<00000000>]    lr : [<c03257e0>]    psr: 60000193
sp : c0725db8  ip : 00000000  fp : c0725df4
r10: 00000001  r9 : 00000193  r8 : ef3ccab4
r7 : ef3cca10  r6 : eea4586c  r5 : 00000000  r4 : ef19ceb4
r3 : 00000000  r2 : 0000009c  r1 : c0725dc4  r0 : ef19ceb4

This patch adds a condition to avoid the dereference.

Fixes: e73a9891 ("usb: renesas_usbhs: add DMAEngine support")
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

buflen by default (256) is smaller than wMaxPacketSize (512) in high-speed
devices.

That caused the OUT endpoint to freeze if the host send any data packet of
length greater than 256 bytes.

This is an example dump of what happended on that enpoint:
HOST:   [DATA][Length=260][...]
DEVICE: [NAK]
HOST:   [PING]
DEVICE: [NAK]
HOST:   [PING]
DEVICE: [NAK]
...
HOST:   [PING]
DEVICE: [NAK]

This patch fixes this problem by setting the minimum usb_request's buffer size
for the OUT endpoint as its wMaxPacketSize.
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

gcc warns about the use of regulators in phy_8x16_probe:

    drivers/usb/phy/phy-qcom-8x16-usb.c: In function 'phy_8x16_probe':
    drivers/usb/phy/phy-qcom-8x16-usb.c:284:13: error: 'regs[0].consumer' may be used uninitialized in this function [-Werror=maybe-uninitialized]
    drivers/usb/phy/phy-qcom-8x16-usb.c:285:13: error: 'regs[1].consumer' may be used uninitialized in this function [-Werror=maybe-uninitialized]
    drivers/usb/phy/phy-qcom-8x16-usb.c:286:12: error: 'regs[2].consumer' may be used uninitialized in this function [-Werror=maybe-uninitialized]

According to Mark Brown, this is the result of various abuses
of the PHY interfaces [1], so let's fix the driver instead.

This puts the regulator bulk data into the device structure so it
gets properly initialized and lets us call regulator_bulk_enable()
and regulator_bulk_disable() rather than open-coding them.

Setting the voltages the way the driver does is rather pointless
because for each regulator there is only one valid voltage
range, so that can just get set up in the DT. As there doesn't
seem to be any user of the newly added driver yet, we can simply
make sure the DTs are setting this up right when they get added.

I'm also fixing the handling of regulator_bulk_enable() failure.
Right now, the driver just ignores any failure, which doesn't make
sense, so I'm changing it to loudly complain (in case we actually
had a bug here) and error out.

Doing a fly-by review of the driver, I notice a couple of other
problems that I'm not addressing here:

- It really should not have been written as a USB PHY driver, but
  instead should use the PHY subsystem.

- The DT compatible string does not follow the usual conventions,
  and it should have a proper identifier in it rather than a wildcard.

- The example in the devicetree binding lists a register address
  that is the same as the actual EHCI host controller in the SoC
  as well as the otg-snps and the ci-hdrc device, which indicates
  that these are probably not even distinct devices (or all but
  one of them are wrong), and if more than one of them tries to
  request the resources correctly, they fail.

[1] https://lkml.org/lkml/2016/1/26/267Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

The wFunctionalitySupport field should be __le16.
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Access multi-byte fields of the SSP Dev Cap descriptor using the correct
endianness.

Fixes: f228a8de ("usb: gadget: composite: Return SSP Dev Cap descriptor")
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

UDC driver should NEVER do anything behind
udc-core's back, so let's stop disabling endpoints
we don't exactly own - rather we provide as
resources for gadget drivers. This fixes the
regression reported by Gil.
Reported-by: Gil Weber <gil.weber@servelec-technologies.com>
Tested-by: Gil Weber <gil.weber@servelec-technologies.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

We were exitting the function before actually
renaming anything. While at that, also always leave
control endpoint un-renamed.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

It's a requirement that we release controller's lock
while calling gadget API function pointers. This
patch just fixes that long standing bug.
Signed-off-by: Jiebing Li <jiebing.li@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

According to Synopsys Databook, we shouldn't be
relying on GCTL.CORESOFTRESET bit as that's only for
debugging purposes. Instead, let's use DCTL.CSFTRST
if we're OTG or PERIPHERAL mode.

Host side block will be reset by XHCI driver if
necessary. Note that this reduces amount of time
spent on dwc3_probe() by a long margin.

We're still gonna wait for reset to finish for a
long time (default to 1ms max), but tests show that
the reset polling loop executed at most 19 times
(modprobe dwc3 && modprobe -r dwc3 executed 1000
times in a row).
Suggested-by: Mian Yousaf Kaukab <yousaf.kaukab@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Since f_midi_transmit is called by both ALSA and USB sub-systems, it can
potentially cause a race condition between both calls because f_midi_transmit
is not reentrant nor thread-safe. This is due to an implementation detail that
the transmit function looks for the next available usb request from the fifo
and only enqueues it if there is data to send, otherwise just re-uses it. So,
if both ALSA and USB frameworks calls this function at the same time,
kfifo_seek() will return the same usb_request, which will cause a race
condition.

To solve this problem a syncronization mechanism is necessary. In this case it
is used a spinlock since f_midi_transmit is also called by usb_request->complete
callback in interrupt context.

Cc: <stable@vger.kernel.org> # v4.5+
Fixes: e1e3d7ec ("usb: gadget: f_midi: pre-allocate IN requests")
Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

Pull Ceph updates from Sage Weil:
 "There is quite a bit here, including some overdue refactoring and
  cleanup on the mon_client and osd_client code from Ilya, scattered
  writeback support for CephFS and a pile of bug fixes from Zheng, and a
  few random cleanups and fixes from others"

[ I already decided not to pull this because of it having been rebased
  recently, but ended up changing my mind after all.  Next time I'll
  really hold people to it.  Oh well.   - Linus ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (34 commits)
  libceph: use KMEM_CACHE macro
  ceph: use kmem_cache_zalloc
  rbd: use KMEM_CACHE macro
  ceph: use lookup request to revalidate dentry
  ceph: kill ceph_get_dentry_parent_inode()
  ceph: fix security xattr deadlock
  ceph: don't request vxattrs from MDS
  ceph: fix mounting same fs multiple times
  ceph: remove unnecessary NULL check
  ceph: avoid updating directory inode's i_size accidentally
  ceph: fix race during filling readdir cache
  libceph: use sizeof_footer() more
  ceph: kill ceph_empty_snapc
  ceph: fix a wrong comparison
  ceph: replace CURRENT_TIME by current_fs_time()
  ceph: scattered page writeback
  libceph: add helper that duplicates last extent operation
  libceph: enable large, variable-sized OSD requests
  libceph: osdc->req_mempool should be backed by a slab pool
  libceph: make r_request msg_size calculation clearer
  ...

Pull orangefs filesystem from Mike Marshall.

This finally merges the long-pending orangefs filesystem, which has been
much cleaned up with input from Al Viro over the last six months.  From
the documentation file:

 "OrangeFS is an LGPL userspace scale-out parallel storage system.  It
  is ideal for large storage problems faced by HPC, BigData, Streaming
  Video, Genomics, Bioinformatics.

  Orangefs, originally called PVFS, was first developed in 1993 by Walt
  Ligon and Eric Blumer as a parallel file system for Parallel Virtual
  Machine (PVM) as part of a NASA grant to study the I/O patterns of
  parallel programs.

  Orangefs features include:

    - Distributes file data among multiple file servers
    - Supports simultaneous access by multiple clients
    - Stores file data and metadata on servers using local file system
      and access methods
    - Userspace implementation is easy to install and maintain
    - Direct MPI support
    - Stateless"

see Documentation/filesystems/orangefs.txt for more in-depth details.

* tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux: (174 commits)
  orangefs: fix orangefs_superblock locking
  orangefs: fix do_readv_writev() handling of error halfway through
  orangefs: have ->kill_sb() evict the VFS side of things first
  orangefs: sanitize ->llseek()
  orangefs-bufmap.h: trim unused junk
  orangefs: saner calling conventions for getting a slot
  orangefs_copy_{to,from}_bufmap(): don't pass bufmap pointer
  orangefs: get rid of readdir_handle_s
  ornagefs: ensure that truncate has an up to date inode size
  orangefs: move code which sets i_link to orangefs_inode_getattr
  orangefs: remove needless wrapper around GFP_KERNEL
  orangefs: remove wrapper around mutex_lock(&inode->i_mutex)
  orangefs: refactor inode type or link_target change detection
  orangefs: use new getattr for revalidate and remove old getattr
  orangefs: use new getattr in inode getattr and permission
  orangefs: use new orangefs_inode_getattr to get size in write and llseek
  orangefs: use new orangefs_inode_getattr to create new inodes
  orangefs: rename orangefs_inode_getattr to orangefs_inode_old_getattr
  orangefs: remove inode->i_lock wrapper
  orangefs: put register_chrdev immediately before register_filesystem
  ...

Pull NTB bug fixes from Jon Mason:
 "NTB bug fixes for tasklet from spinning forever, link errors,
  translation window setup, NULL ptr dereference, and ntb-perf errors.

  Also, a modification to the driver API that makes _addr functions
  optional"

* tag 'ntb-4.6' of git://github.com/jonmason/ntb:
  NTB: Remove _addr functions from ntb_hw_amd
  NTB: Make _addr functions optional in the API
  NTB: Fix incorrect clean up routine in ntb_perf
  NTB: Fix incorrect return check in ntb_perf
  ntb: fix possible NULL dereference
  ntb: add missing setup of translation window
  ntb: stop link work when we do not have memory
  ntb: stop tasklet from spinning forever during shutdown.
  ntb: perf test: fix address space confusion

Pull more SCSI updates from James Bottomley:
 "The only new stuff which missed the first pull request is an update to
  the UFS driver.

  The rest is an assortment of bug fixes and minor tweaks which appeared
  recently (some are fixes for recent code and some are stuff spotted
  recently by the checkers or the new gcc-6 compiler [most of Arnd's
  stuff])"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (32 commits)
  scsi_common: do not clobber fixed sense information
  scsi: ufs: select CONFIG_NLS
  scsi: fc: use get/put_unaligned64 for wwn access
  fnic: move printk()s outside of the critical code section.
  qla2xxx: avoid maybe_uninitialized warning
  megaraid_sas: add missing curly braces in ioctl handler
  lpfc: fix misleading indentation
  scsi_transport_sas: add 'scsi_target_id' sysfs attribute
  scsi_dh_alua: uninitialized variable in alua_check_vpd()
  scsi: ufs-qcom: add printouts of testbus debug registers
  scsi: ufs-qcom: enable/disable the device ref clock
  scsi: ufs-qcom: set PA_Local_TX_LCC_Enable before link startup
  scsi: ufs: add device quirk delay before putting UFS rails in LPM
  scsi: ufs: fix leakage during link off state
  scsi: ufs: tune UniPro parameters to optimize hibern8 exit time
  scsi: ufs: handle non spec compliant bkops behaviour by device
  scsi: ufs: add retry for query descriptors
  scsi: ufs: add error recovery after DL NAC error
  scsi: ufs: make error handling bit faster
  scsi: ufs: disable vccq if it's not needed by UFS device
  ...

Commit 0b81d077 ("fs crypto: move per-file encryption from f2fs
tree to fs/crypto") moved the f2fs crypto files to fs/crypto/ and
renamed the symbol prefixes from "f2fs_" to "fscrypt_" (and from "F2FS_"
to just "FS" for preprocessor symbols).

Because of the symbol renaming, it's a bit hard to see it as a file
move: use

    git show -M30 0b81d077

to lower the rename detection to just 30% similarity and make git show
the files as renamed (the header file won't be shown as a rename even
then - since all it contains is symbol definitions, it looks almost
completely different).

Even with the renames showing as renames, the diffs are not all that
easy to read, since so much is just the renames.  But Eric Biggers
noticed that it's not just all renames: the initialization of the
xts_tweak had been broken too, using the inode number rather than the
page offset.

That's not right - it makes the xfs_tweak the same for all pages of each
inode.  It _might_ make sense to make the xfs_tweak contain both the
offset _and_ the inode number, but not just the inode number.
Reported-by: Eric Biggers <ebiggers3@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Kernel zero day testing warned about address space confusion.  A virtual
iomem address was used where a physical address is expected.  The
offending functions implement an optional part of the api, so they are
removed.  They can be added later, after testing.

Fixes: a1b36958Signed-off-by: Allen Hubbe <Allen.Hubbe@emc.com>
Acked-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

* switch orangefs_remount() to taking ORANGEFS_SB(sb) instead of sb
* remove from the list _before_ orangefs_unmount() - request_mutex
in the latter will make sure that nothing observed in the loop in
ORANGEFS_DEV_REMOUNT_ALL handling will get freed until the end
of loop
* on removal, keep the forward pointer and zero the back one.  That
way we can drop and regain the spinlock in the loop body (again,
ORANGEFS_DEV_REMOUNT_ALL one) and still be able to get to the
rest of the list.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Error should only be returned if nothing had been read/written.
Otherwise we need to report a short read/write instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

a) open files can't have NULL inodes
b) it's SEEK_END, not ORANGEFS_SEEK_END; no need to get cute.
c) make_bad_inode() on lseek()?
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

just have it return the slot number or -E... - the caller checks
the sign anyway
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

it's always __orangefs_bufmap
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

no point, really - we couldn't keep those across the calls of
getdents(); it would be too easy to DoS, having all slots exhausted.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Merge fourth patch-bomb from Andrew Morton:
 "A lot more stuff than expected, sorry.  A bunch of ocfs2 reviewing was
  finished off.

   - mhocko's oom-reaper out-of-memory-handler changes

   - ocfs2 fixes and features

   - KASAN feature work

   - various fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (42 commits)
  thp: fix typo in khugepaged_scan_pmd()
  MAINTAINERS: fill entries for KASAN
  mm/filemap: generic_file_read_iter(): check for zero reads unconditionally
  kasan: test fix: warn if the UAF could not be detected in kmalloc_uaf2
  mm, kasan: stackdepot implementation. Enable stackdepot for SLAB
  arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections
  mm, kasan: add GFP flags to KASAN API
  mm, kasan: SLAB support
  kasan: modify kmalloc_large_oob_right(), add kmalloc_pagealloc_oob_right()
  include/linux/oom.h: remove undefined oom_kills_count()/note_oom_kill()
  mm/page_alloc: prevent merging between isolated and other pageblocks
  drivers/memstick/host/r592.c: avoid gcc-6 warning
  ocfs2: extend enough credits for freeing one truncate record while replaying truncate records
  ocfs2: extend transaction for ocfs2_remove_rightmost_path() and ocfs2_update_edge_lengths() before to avoid inconsistency between inode and et
  ocfs2/dlm: move lock to the tail of grant queue while doing in-place convert
  ocfs2: solve a problem of crossing the boundary in updating backups
  ocfs2: fix occurring deadlock by changing ocfs2_wq from global to local
  ocfs2/dlm: fix BUG in dlm_move_lockres_to_recovery_list
  ocfs2/dlm: fix race between convert and recovery
  ocfs2: fix a deadlock issue in ocfs2_dio_end_io_write()
  ...

Pull power management fixlet from Rafael Wysocki:
 "One of commits in my previous pull request changed the permissions of
  drivers/power/avs/rockchip-io-domain.c to executable by mistake"

* tag 'pm+acpi-4.6-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Fix permissions of drivers/power/avs/rockchip-io-domain.c

Pull ia64 update from Tony Luck:
 "Wire up new system calls p{read,write}v2 for ia64"

* tag 'please-pull-preadv2' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  [IA64] Enable preadv2 and pwritev2 syscalls for ia64

Pull more input updates from Dmitry Torokhov:
 "Second round of updates for the input subsystem.

  The BYD PS/2 protocol driver now uses absolute reporting mode and
  should behave more like other touchpads; Synaptics driver needed to
  extend one of its quirks to a newer firmware version, and a few USB
  drivers got tightened up checks for the contents of their descriptors"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: sur40 - fix DMA on stack
  Input: ati_remote2 - fix crashes on detecting device with invalid descriptor
  Input: synaptics - handle spurious release of trackstick buttons, again
  Input: synaptics-rmi4 - remove check of Non-NULL array
  Input: byd - enable absolute mode
  Input: ims-pcu - sanity check against missing interfaces
  Input: melfas_mip4 - add hw_version sysfs attribute

!PageLRU should lead to SCAN_PAGE_LRU, not SCAN_SCAN_ABORT result.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If
 - generic_file_read_iter() gets called with a zero read length,
 - the read offset is at a page boundary,
 - IOCB_DIRECT is not set
-  and the page in question hasn't made it into the page cache yet,
then do_generic_file_read() will trigger a readahead with a req_size hint
of zero.

Since roundup_pow_of_two(0) is undefined, UBSAN reports

  UBSAN: Undefined behaviour in include/linux/log2.h:63:13
  shift exponent 64 is too large for 64-bit type 'long unsigned int'
  CPU: 3 PID: 1017 Comm: sa1 Tainted: G L 4.5.0-next-20160318+ #14
  [...]
  Call Trace:
   [...]
   [<ffffffff813ef61a>] ondemand_readahead+0x3aa/0x3d0
   [<ffffffff813ef61a>] ? ondemand_readahead+0x3aa/0x3d0
   [<ffffffff813c73bd>] ? find_get_entry+0x2d/0x210
   [<ffffffff813ef9c3>] page_cache_sync_readahead+0x63/0xa0
   [<ffffffff813cc04d>] do_generic_file_read+0x80d/0xf90
   [<ffffffff813cc955>] generic_file_read_iter+0x185/0x420
   [...]
   [<ffffffff81510b06>] __vfs_read+0x256/0x3d0
   [...]

when get_init_ra_size() gets called from ondemand_readahead().

The net effect is that the initial readahead size is arch dependent for
requested read lengths of zero: for example, since

  1UL << (sizeof(unsigned long) * 8)

evaluates to 1 on x86 while its result is 0 on ARMv7, the initial readahead
size becomes 4 on the former and 0 on the latter.

What's more, whether or not the file access timestamp is updated for zero
length reads is decided differently for the two cases of IOCB_DIRECT
being set or cleared: in the first case, generic_file_read_iter()
explicitly skips updating that timestamp while in the latter case, it is
always updated through the call to do_generic_file_read().

According to POSIX, zero length reads "do not modify the last data access
timestamp" and thus, the IOCB_DIRECT behaviour is POSIXly correct.

Let generic_file_read_iter() unconditionally check the requested read
length at its entry and return immediately with success if it is zero.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>