Merge branch 'lkmm' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/core

Pull v5.9 LKMM changes from Paul E. McKenney.

Mostly documentation changes, but also some new litmus tests for atomic ops.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge branch 'kcsan' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/core

Pull v5.9 KCSAN bits from Paul E. McKenney.

Perhaps the most important change is that GCC 11 now has all fixes in place
to support KCSAN, so GCC support can be enabled again.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Conflicts:
	arch/arm/include/asm/percpu.h

As Stephen Rothwell noted, there's a conflict between this commit
in locking/core:

  a21ee605 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")

and this fresh upstream commit:

  aa54ea90 ("ARM: percpu.h: fix build error")

a21ee605 is a simpler solution to the dependency problem and doesn't
further increase header hell - so this conflict resolution effectively
reverts aa54ea90 and uses the a21ee605 solution.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

To improve the general usefulness of the IRQ state trace events with
KCSAN enabled, save and restore the trace information when entering and
exiting the KCSAN runtime as well as when generating a KCSAN report.

Without this, reporting the IRQ trace events (whether via a KCSAN report
or outside of KCSAN via a lockdep report) is rather useless due to
continuously being touched by KCSAN. This is because if KCSAN is
enabled, every instrumented memory access causes changes to IRQ trace
events (either by KCSAN disabling/enabling interrupts or taking
report_lock when generating a report).

Before "lockdep: Prepare for NMI IRQ state tracking", KCSAN avoided
touching the IRQ trace events via raw_local_irq_save/restore() and
lockdep_off/on().

Fixes: 248591f5 ("kcsan: Make KCSAN compatible with new IRQ state tracking")
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200729110916.3920464-2-elver@google.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

Refactor the IRQ trace events fields, used for printing information
about the IRQ trace events, into a separate struct 'irqtrace_events'.

This improves readability by separating the information only used in
reporting, as well as enables (simplified) storing/restoring of
irqtrace_events snapshots.

No functional change intended.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200729110916.3920464-1-elver@google.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

Pull more drm fixes from Dave Airlie:
 "As mentioned previously this contains the nouveau regression fix.

  amdgpu had three fixes outstanding as well, one revert, an info leak
  and use after free. The use after free is a bit trickier than I'd
  like, and I've personally gone over it to confirm I'm happy that it is
  doing what it says.

  nouveau:
   - final modifiers regression fix

  amdgpu:
   - Revert a fix which caused other regressions
   - Fix potential kernel info leak
   - Fix a use-after-free bug that was uncovered by another change in 5.7"

* tag 'drm-fixes-2020-07-31' of git://anongit.freedesktop.org/drm/drm:
  drm/nouveau: Accept 'legacy' format modifiers
  Revert "drm/amdgpu: Fix NULL dereference in dpm sysfs handlers"
  drm/amd/display: Clear dm_state for fast updates
  drm/amdgpu: Prevent kernel-infoleak in amdgpu_info_ioctl()

Merge tag 'amd-drm-fixes-5.8-2020-07-30' of git://people.freedesktop.org/~agd5f/linux into drm-fixes

amd-drm-fixes-5.8-2020-07-30:

amdgpu:
- Revert a fix which caused other regressions
- Fix potential kernel info leak
- Fix a use-after-free bug that was uncovered by another change in 5.7
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Alex Deucher <alexdeucher@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200730154338.244104-1-alexander.deucher@amd.com

Accept the DRM_FORMAT_MOD_NVIDIA_16BX2_BLOCK()
family of modifiers to handle broken userspace
Xorg modesetting and Mesa drivers. Existing Mesa
drivers are still aware of only these older
format modifiers which do not differentiate
between different variations of the block linear
layout. When the format modifier support flag was
flipped in the nouveau kernel driver, the X.org
modesetting driver began attempting to use its
format modifier-enabled framebuffer path. Because
the set of format modifiers advertised by the
kernel prior to this change do not intersect with
the set of format modifiers advertised by Mesa,
allocating GBM buffers using format modifiers
fails and the modesetting driver falls back to
non-modifier allocation. However, it still later
queries the modifier of the GBM buffer when
creating its DRM-KMS framebuffer object, receives
the old-format modifier from Mesa, and attempts
to create a framebuffer with it. Since the kernel
is still not aware of these formats, this fails.

Userspace should not be attempting to query format
modifiers of GBM buffers allocated with a non-
format-modifier-aware allocation path, but to
avoid breaking existing userspace behavior, this
change accepts the old-style format modifiers when
creating framebuffers and applying them to planes
by translating them to the equivalent new-style
modifier. To accomplish this, some layout
parameters must be assumed to match properties of
the device targeted by the relevant ioctls. To
avoid perpetuating misuse of the old-style
modifiers, this change does not advertise support
for them. Doing so would imply compatibility
between devices with incompatible memory layouts.

Tested with Xorg 1.20 modesetting driver,
weston@c46c70dac84a4b3030cd05b380f9f410536690fc,
gnome & KDE wayland desktops from Ubuntu 18.04,
and sway 1.5
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Fixes: fa4f4c21 ("drm/nouveau/kms: Support NVIDIA format modifiers")
Link: https://lkml.org/lkml/2020/6/30/1251Signed-off-by: James Jones <jajones@nvidia.com>
Acked-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Fix kernel oops observed when an ext adv data is larger than 31 bytes.

This can be reproduced by setting up an advertiser with advertisement
larger than 31 bytes.  The issue is not sensitive to the advertisement
content.  In particular, this was reproduced with an advertisement of
229 bytes filled with 'A'.  See stack trace below.

This is fixed by not catching ext_adv as legacy adv are only cached to
be able to concatenate a scanable adv with its scan response before
sending it up through mgmt.

With ext_adv, this is no longer necessary.

  general protection fault: 0000 [#1] SMP PTI
  CPU: 6 PID: 205 Comm: kworker/u17:0 Not tainted 5.4.0-37-generic #41-Ubuntu
  Hardware name: Dell Inc. XPS 15 7590/0CF6RR, BIOS 1.7.0 05/11/2020
  Workqueue: hci0 hci_rx_work [bluetooth]
  RIP: 0010:hci_bdaddr_list_lookup+0x1e/0x40 [bluetooth]
  Code: ff ff e9 26 ff ff ff 0f 1f 44 00 00 0f 1f 44 00 00 55 48 8b 07 48 89 e5 48 39 c7 75 0a eb 24 48 8b 00 48 39 f8 74 1c 44 8b 06 <44> 39 40 10 75 ef 44 0f b7 4e 04 66 44 39 48 14 75 e3 38 50 16 75
  RSP: 0018:ffffbc6a40493c70 EFLAGS: 00010286
  RAX: 4141414141414141 RBX: 000000000000001b RCX: 0000000000000000
  RDX: 0000000000000000 RSI: ffff9903e76c100f RDI: ffff9904289d4b28
  RBP: ffffbc6a40493c70 R08: 0000000093570362 R09: 0000000000000000
  R10: 0000000000000000 R11: ffff9904344eae38 R12: ffff9904289d4000
  R13: 0000000000000000 R14: 00000000ffffffa3 R15: ffff9903e76c100f
  FS: 0000000000000000(0000) GS:ffff990434580000(0000) knlGS:0000000000000000
  CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007feed125a000 CR3: 00000001b860a003 CR4: 00000000003606e0
  Call Trace:
    process_adv_report+0x12e/0x560 [bluetooth]
    hci_le_meta_evt+0x7b2/0xba0 [bluetooth]
    hci_event_packet+0x1c29/0x2a90 [bluetooth]
    hci_rx_work+0x19b/0x360 [bluetooth]
    process_one_work+0x1eb/0x3b0
    worker_thread+0x4d/0x400
    kthread+0x104/0x140

Fixes: c215e939 ("Bluetooth: Process extended ADV report event")
Reported-by: Andy Nguyen <theflow@google.com>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Signed-off-by: Alain Michaud <alainm@chromium.org>
Tested-by: Sonny Sasaka <sonnysasaka@chromium.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull virtio fixes from Michael Tsirkin:
 "A couple of last minute bugfixes"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio-mem: Fix build error due to improper use 'select'
  virtio_balloon: fix up endian-ness for free cmd id
  virtio-balloon: Document byte ordering of poison_val
  vhost/scsi: fix up req type endian-ness
  firmware: Fix a reference count leak.

Fix build error for the case:
  defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)

config: keystone_defconfig

  CC      arch/arm/kernel/signal.o
  In file included from ../include/linux/random.h:14,
                    from ../arch/arm/kernel/signal.c:8:
  ../arch/arm/include/asm/percpu.h: In function ‘__my_cpu_offset’:
  ../arch/arm/include/asm/percpu.h:29:34: error: ‘current_stack_pointer’ undeclared (first use in this function); did you mean ‘user_stack_pointer’?
      : "Q" (*(const unsigned long *)current_stack_pointer));
                                     ^~~~~~~~~~~~~~~~~~~~~
                                     user_stack_pointer

Fixes: f227e3ec ("random32: update the net random state on interrupt and activity")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull PCI fix from Bjorn Helgaas:
 "Disable ASPM on ASM1083/1085 PCIe-to-PCI bridge (Robert Hancock)"

* tag 'pci-v5.8-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI/ASPM: Disable ASPM on ASMedia ASM1083/1085 PCIe-to-PCI bridge

Pull block fixes from Jens Axboe:
 "Three NVMe fixes"

* tag 'block-5.8-2020-07-30' of git://git.kernel.dk/linux-block:
  nvme: add a Identify Namespace Identification Descriptor list quirk
  nvme-pci: prevent SK hynix PC400 from using Write Zeroes command
  nvme-tcp: fix possible hang waiting for icresp response

Pull io_uring fixes from Jens Axboe:
 "Two small fixes for corner/error cases"

* tag 'io_uring-5.8-2020-07-30' of git://git.kernel.dk/linux-block:
  io_uring: fix lockup in io_fail_links()
  io_uring: fix ->work corruption with poll_add

Daniel Díaz and Kees Cook independently reported that commit
f227e3ec ("random32: update the net random state on interrupt and
activity") broke arm64 due to a circular dependency on include files
since the addition of percpu.h in random.h.

The correct fix would definitely be to move all the prandom32 stuff out
of random.h but for backporting, a smaller solution is preferred.

This one replaces linux/percpu.h with asm/percpu.h, and this fixes the
problem on x86_64, arm64, arm, and mips.  Note that moving percpu.h
around didn't change anything and that removing it entirely broke
differently.  When backporting, such options might still be considered
if this patch fails to help.

[ It turns out that an alternate fix seems to be to just remove the
  troublesome <asm/pointer_auth.h> remove from the arm64 <asm/smp.h>
  that causes the circular dependency.

  But we might as well do the whole belt-and-suspenders thing, and
  minimize inclusion in <linux/random.h> too. Either will fix the
  problem, and both are good changes.   - Linus ]
Reported-by: Daniel Díaz <daniel.diaz@linaro.org>
Reported-by: Kees Cook <keescook@chromium.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Fixes: f227e3ec
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

As noted in:
https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt
"select should be used with care. select will force a symbol to a
value without visiting the dependencies."
Config VIRTIO_MEM should not select CONTIG_ALLOC directly.
Otherwise it will cause an error:
https://bugzilla.kernel.org/show_bug.cgi?id=208245Signed-off-by: Weilong Chen <chenweilong@huawei.com>
Link: https://lore.kernel.org/r/20200619080333.194753-1-chenweilong@huawei.com
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>

This regressed some working configurations so revert it.  Will
fix this properly for 5.9 and backport then.

This reverts commit 38e0c89a.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

This patch fixes a race condition that causes a use-after-free during
amdgpu_dm_atomic_commit_tail. This can occur when 2 non-blocking commits
are requested and the second one finishes before the first. Essentially,
this bug occurs when the following sequence of events happens:

1. Non-blocking commit #1 is requested w/ a new dm_state #1 and is
deferred to the workqueue.

2. Non-blocking commit #2 is requested w/ a new dm_state #2 and is
deferred to the workqueue.

3. Commit #2 starts before commit #1, dm_state #1 is used in the
commit_tail and commit #2 completes, freeing dm_state #1.

4. Commit #1 starts after commit #2 completes, uses the freed dm_state
1 and dereferences a freelist pointer while setting the context.

Since this bug has only been spotted with fast commits, this patch fixes
the bug by clearing the dm_state instead of using the old dc_state for
fast updates. In addition, since dm_state is only used for its dc_state
and amdgpu_dm_atomic_commit_tail will retain the dc_state if none is found,
removing the dm_state should not have any consequences in fast updates.

This use-after-free bug has existed for a while now, but only caused a
noticeable issue starting from 5.7-rc1 due to 3202fa62 ("slub: relocate
freelist pointer to middle of object") moving the freelist pointer from
dm_state->base (which was unused) to dm_state->context (which is
dereferenced).

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207383
Fixes: bd200d19 ("drm/amd/display: Don't replace the dc_state for fast updates")
Reported-by: Duncan <1i5t5.duncan@cox.net>
Signed-off-by: Mazin Rezk <mnrzk@protonmail.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Compiler leaves a 4-byte hole near the end of `dev_info`, causing
amdgpu_info_ioctl() to copy uninitialized kernel stack memory to userspace
when `size` is greater than 356.

In 2015 we tried to fix this issue by doing `= {};` on `dev_info`, which
unfortunately does not initialize that 4-byte hole. Fix it by using
memset() instead.

Cc: stable@vger.kernel.org
Fixes: c193fa91 ("drm/amdgpu: information leak in amdgpu_info_ioctl()")
Fixes: d38ceaf9 ("drm/amdgpu: add core driver (v4)")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

It turns out that the plugin right now ends up being really unhappy
about the change from 'static' to 'extern' storage that happened in
commit f227e3ec ("random32: update the net random state on interrupt
and activity").

This is probably a trivial fix for the latent_entropy plugin, but for
now, just remove net_rand_state from the list of things the plugin
worries about.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Recently ASPM handling was changed to allow ASPM on PCIe-to-PCI/PCI-X
bridges.  Unfortunately the ASMedia ASM1083/1085 PCIe to PCI bridge device
doesn't seem to function properly with ASPM enabled.  On an Asus PRIME
H270-PRO motherboard, it causes errors like these:

  pcieport 0000:00:1c.0: AER: PCIe Bus Error: severity=Corrected, type=Data Link Layer, (Transmitter ID)
  pcieport 0000:00:1c.0: AER:   device [8086:a292] error status/mask=00003000/00002000
  pcieport 0000:00:1c.0: AER:    [12] Timeout
  pcieport 0000:00:1c.0: AER: Corrected error received: 0000:00:1c.0
  pcieport 0000:00:1c.0: AER: can't find device of ID00e0

In addition to flooding the kernel log, this also causes the machine to
wake up immediately after suspend is initiated.

The device advertises ASPM L0s and L1 support in the Link Capabilities
register, but the ASMedia web page for ASM1083 [1] claims "No PCIe ASPM
support".

Windows 10 (build 2004) enables L0s, but it also logs correctable PCIe
errors.

Add a quirk to disable ASPM for this device.

[1] https://www.asmedia.com.tw/eng/e_show_products.php?cate_index=169&item=114

[bhelgaas: commit log]
Fixes: 66ff14e5 ("PCI/ASPM: Allow ASPM on links to PCIe-to-PCI/PCI-X Bridges")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=208667
Link: https://lore.kernel.org/r/20200722021803.17958-1-hancockrwd@gmail.comSigned-off-by: Robert Hancock <hancockrwd@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Pull audit fixes from Paul Moore:
 "One small audit fix that you can hopefully merge before v5.8 is
  released. Unfortunately it is a revert of a patch that went in during
  the v5.7 window and we just recently started to see some bug reports
  relating to that commit.

  We are working on a proper fix, but I'm not yet clear on when that
  will be ready and we need to fix the v5.7 kernels anyway, so in the
  interest of time a revert seemed like the best solution right now"

* tag 'audit-pr-20200729' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
  revert: 1320a405 ("audit: trigger accompanying records when no rules present")

Pull 9p fixes from Dominique Martinet:
 "A couple of syzcaller fixes for 5.8

  The first one in particular has been quite noisy ("broke" in -rc5) so
  this would be worth landing even this late even if users likely won't
  see a difference"

* tag '9p-for-5.8-2' of git://github.com/martinetd/linux:
  9p/trans_fd: Fix concurrency del of req_list in p9_fd_cancelled/p9_read_work
  net/9p: validate fds in p9_fd_open

Pull drm fixes from Dave Airlie:
 "The nouveau fixes missed the last pull by a few hours, and we had a
  few arm driver/panel/bridge fixes come in.

  This is possibly a bit more than I'm comfortable sending at this
  stage, but I've looked at each patch, the core + nouveau patches fix
  regressions, and the arm related ones are all around screens turning
  on and working, and are mostly trivial patches, the line count is
  mostly in comments.

  core:
   - fix possible use-after-free

  drm_fb_helper:
   - regression fix to use memcpy_io on bochs' sparc64

  nouveau:
   - format modifiers fixes
   - HDA regression fix
   - turing modesetting race fix

  of:
   - fix a double free

  dbi:
   - fix SPI Type 1 transfer

  mcde:
   - fix screen stability crash

  panel:
   - panel: fix display noise on auo,kd101n80-45na
   - panel: delay HPD checks for boe_nv133fhm_n61

  bridge:
   - bridge: drop connector check in nwl-dsi bridge
   - bridge: set proper bridge type for adv7511"

* tag 'drm-fixes-2020-07-29' of git://anongit.freedesktop.org/drm/drm:
  drm: hold gem reference until object is no longer accessed
  drm/dbi: Fix SPI Type 1 (9-bit) transfer
  drm/drm_fb_helper: fix fbdev with sparc64
  drm/mcde: Fix stability issue
  drm/bridge: nwl-dsi: Drop DRM_BRIDGE_ATTACH_NO_CONNECTOR check.
  drm/panel: Fix auo, kd101n80-45na horizontal noise on edges of panel
  drm: panel: simple: Delay HPD checking on boe_nv133fhm_n61 for 15 ms
  drm/bridge/adv7511: set the bridge type properly
  drm: of: Fix double-free bug
  drm/nouveau/fbcon: zero-initialise the mode_cmd2 structure
  drm/nouveau/fbcon: fix module unload when fbcon init has failed for some reason
  drm/nouveau/kms/tu102: wait for core update to complete when assigning windows
  drm/nouveau/kms/gf100: use correct format modifiers
  drm/nouveau/disp/gm200-: fix regression from HDA SOR selection changes

This modifies the first 32 bits out of the 128 bits of a random CPU's
net_rand_state on interrupt or CPU activity to complicate remote
observations that could lead to guessing the network RNG's internal
state.

Note that depending on some network devices' interrupt rate moderation
or binding, this re-seeding might happen on every packet or even almost
never.

In addition, with NOHZ some CPUs might not even get timer interrupts,
leaving their local state rarely updated, while they are running
networked processes making use of the random state.  For this reason, we
also perform this update in update_process_times() in order to at least
update the state when there is user or system activity, since it's the
only case we care about.
Reported-by: Amit Klein <aksecurity@gmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

free cmd id is read using virtio endian, spec says all fields
in balloon are LE. Fix it up.

Fixes: 86a55978 ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Wei Wang <wei.w.wang@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>

The poison_val field in the virtio_balloon_config is treated as a
little-endian field by the host. Since we are currently only having to deal
with a single byte poison value this isn't a problem, however if the value
should ever expand it would cause byte ordering issues. Document that in
the code so that we know that if the value should ever expand we need to
byte swap the value on big-endian architectures.
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Link: https://lore.kernel.org/r/20200713203539.17140.71425.stgit@localhost.localdomainSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>

vhost/scsi doesn't handle type conversion correctly
for request type when using virtio 1.0 and up for BE,
or cross-endian platforms.

Fix it up using vhost_32_to_cpu.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Pull NVMe fixes from Christoph.

* 'nvme-5.8' of git://git.infradead.org/nvme:
  nvme: add a Identify Namespace Identification Descriptor list quirk
  nvme-pci: prevent SK hynix PC400 from using Write Zeroes command
  nvme-tcp: fix possible hang waiting for icresp response

kobject_init_and_add() takes reference even when it fails.
If this function returns an error, kobject_put() must be called to
properly clean up the memory associated with the object.
Callback function fw_cfg_sysfs_release_entry() in kobject_put()
can handle the pointer "entry" properly.
Signed-off-by: Qiushi Wu <wu000273@umn.edu>
Link: https://lore.kernel.org/r/20200613190533.15712-1-wu000273@umn.eduSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

Preemption must be disabled before entering a sequence count write side
critical section.  Failing to do so, the seqcount read side can preempt
the write side section and spin for the entire scheduler tick.  If that
reader belongs to a real-time scheduling class, it can spin forever and
the kernel will livelock.

Assert through lockdep that preemption is disabled for seqcount writers.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-9-a.darwish@linutronix.de

Asserting that preemption is enabled or disabled is a critical sanity
check.  Developers are usually reluctant to add such a check in a
fastpath as reading the preemption count can be costly.

Extend the lockdep API with macros asserting that preemption is disabled
or enabled. If lockdep is disabled, or if the underlying architecture
does not support kernel preemption, this assert has no runtime overhead.

References: f54bb2ec ("locking/lockdep: Add IRQs disabled/enabled assertion APIs: ...")
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-8-a.darwish@linutronix.de

raw_seqcount_begin() has the same code as raw_read_seqcount(), with the
exception of masking the sequence counter's LSB before returning it to
the caller.

Note, raw_seqcount_begin() masks the counter's LSB before returning it
to the caller so that read_seqcount_retry() can fail if the counter is
odd -- without the overhead of an extra branching instruction.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-7-a.darwish@linutronix.de

seqlock.h is now included by kernel's RST documentation, but a small
number of the the exported seqlock.h functions are kernel-doc annotated.

Add kernel-doc for all seqlock.h exported APIs.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-6-a.darwish@linutronix.de

The seqlock.h seqcount_t and seqlock_t API definitions are presented in
the chronological order of their development rather than the order that
makes most sense to readers. This makes it hard to follow and understand
the header file code.

Group and reorder all of the exported seqlock.h functions according to
their function.

First, group together the seqcount_t standard read path functions:

    - __read_seqcount_begin()
    - raw_read_seqcount_begin()
    - read_seqcount_begin()

since each function is implemented exactly in terms of the one above
it. Then, group the special-case seqcount_t readers on their own as:

    - raw_read_seqcount()
    - raw_seqcount_begin()

since the only difference between the two functions is that the second
one masks the sequence counter LSB while the first one does not. Note
that raw_seqcount_begin() can actually be implemented in terms of
raw_read_seqcount(), which will be done in a follow-up commit.

Then, group the seqcount_t write path functions, instead of injecting
unrelated seqcount_t latch functions between them, and order them as:

    - raw_write_seqcount_begin()
    - raw_write_seqcount_end()
    - write_seqcount_begin_nested()
    - write_seqcount_begin()
    - write_seqcount_end()
    - raw_write_seqcount_barrier()
    - write_seqcount_invalidate()

which is the expected natural order. This also isolates the seqcount_t
latch functions into their own area, at the end of the sequence counters
section, and before jumping to the next one: sequential locks
(seqlock_t).

Do a similar grouping and reordering for seqlock_t "locking" readers vs.
the "conditionally locking or lockless" ones.

No implementation code was changed in any of the reordering above.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-5-a.darwish@linutronix.de

The seqcount_t latch reader example at the raw_write_seqcount_latch()
kernel-doc comment ends the latch read section with a manual smp memory
barrier and sequence counter comparison.

This is technically correct, but it is suboptimal: read_seqcount_retry()
already contains the same logic of an smp memory barrier and sequence
counter comparison.

End the latch read critical section example with read_seqcount_retry().
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-4-a.darwish@linutronix.de

Align the code samples and note sections inside kernel-doc comments with
tabs. This way they can be properly parsed and rendered by Sphinx. It
also makes the code samples easier to read from text editors.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-3-a.darwish@linutronix.de

Proper documentation for the design and usage of sequence counters and
sequential locks does not exist. Complete the seqlock.h documentation as
follows:

  - Divide all documentation on a seqcount_t vs. seqlock_t basis. The
    description for both mechanisms was intermingled, which is incorrect
    since the usage constrains for each type are vastly different.

  - Add an introductory paragraph describing the internal design of, and
    rationale for, sequence counters.

  - Document seqcount_t writer non-preemptibility requirement, which was
    not previously documented anywhere, and provide a clear rationale.

  - Provide template code for seqcount_t and seqlock_t initialization
    and reader/writer critical sections.

  - Recommend using seqlock_t by default. It implicitly handles the
    serialization and non-preemptibility requirements of writers.

At seqlock.h:

  - Remove references to brlocks as they've long been removed from the
    kernel.

  - Remove references to gcc-3.x since the kernel's minimum supported
    gcc version is 4.9.

References: 0f6ed63b ("no need to keep brlock macros anymore...")
References: 6ec4476a ("Raise gcc version requirement to 4.9")
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-2-a.darwish@linutronix.de

This patch breaks a header loop involving qspinlock_types.h.
The issue is that qspinlock_types.h includes atomic.h, which then
eventually includes kernel.h which could lead back to the original
file via spinlock_types.h.

As ATOMIC_INIT is now defined by linux/types.h, there is no longer
any need to include atomic.h from qspinlock_types.h.  This also
allows the CONFIG_PARAVIRT hack to be removed since it was trying
to prevent exactly this loop.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lkml.kernel.org/r/20200729123316.GC7047@gondor.apana.org.au