If only linear modifier is advertised, since there are many drivers that
only linear supported, the DRM core should handle this rather than
open-coding in every driver. However, there are legacy drivers such as
radeon that do not support modifiers but infer the actual layout of the
underlying buffer. Therefore, a new flag fb_modifiers_not_supported is
introduced for these legacy drivers, and allow_fb_modifiers is replaced
with this new flag.
v3:
- change the order as follows:
1. add fb_modifiers_not_supported flag
2. add default modifiers
3. remove allow_fb_modifiers flag
- add a conditional disable in amdgpu_dm_plane_init()
v4:
- modify kernel docs
v5:
- modify kernel docs
Signed-off-by: Tomohito Esaki <etom@igel.co.jp>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220128060836.11216-2-etom@igel.co.jp
Hot-unplug all firmware-framebuffer devices as part of removing
them via remove_conflicting_framebuffers() et al. Releases all
memory regions to be acquired by native drivers.
Firmware, such as EFI, install a framebuffer while posting the
computer. After removing the firmware-framebuffer device from fbdev,
a native driver takes over the hardware and the firmware framebuffer
becomes invalid.
Firmware-framebuffer drivers, specifically simplefb, don't release
their device from Linux' device hierarchy. It still owns the firmware
framebuffer and blocks the native drivers from loading. This has been
observed in the vmwgfx driver. [1]
Initiating a device removal (i.e., hot unplug) as part of
remove_conflicting_framebuffers() removes the underlying device and
returns the memory range to the system.
[1] https://lore.kernel.org/dri-devel/20220117180359.18114-1-zack@kde.org/
v2:
* rename variable 'dev' to 'device' (Javier)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reported-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
CC: stable@vger.kernel.org # v5.11+
Link: https://patchwork.freedesktop.org/patch/msgid/20220125091222.21457-2-tzimmermann@suse.de
Keep track for which BO a resource was allocated.
This is necessary to move the LRU handling into the resources.
A bit problematic is i915 since it tries to use the resource
interface without a BO which is illegal from the conceptional
point of view.
v2: Document that this is a weak reference and add a workaround for i915
v3: further document that this is protected by ttm_device::lru_lock and
clarify the i915 workaround
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124122514.1832-4-christian.koenig@amd.com
The current code assumes that the RGB444 and YUV444 formats are the
same, but the HDMI 2.0 specification states that:
The three DC_XXbit bits above only indicate support for RGB 4:4:4 at
that pixel size. Support for YCBCR 4:4:4 in Deep Color modes is
indicated with the DC_Y444 bit. If DC_Y444 is set, then YCBCR 4:4:4
is supported for all modes indicated by the DC_XXbit flags.
So if we have YUV444 support and any DC_XXbit flag set but the DC_Y444
flag isn't, we'll assume that we support that deep colour mode for
YUV444 which breaks the specification.
In order to fix this, let's split the edid_hdmi_dc_modes field in struct
drm_display_info into two fields, one for RGB444 and one for YUV444.
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: d0c94692e0 ("drm/edid: Parse and handle HDMI deep color modes.")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220120151625.594595-4-maxime@cerno.tech
The drm_hdmi_avi_infoframe_colorspace() function actually sets the
colorimetry and extended_colorimetry fields in the hdmi_avi_infoframe
structure with DRM_MODE_COLORIMETRY_* values.
To make things worse, the hdmi_avi_infoframe structure also has a
colorspace field used to signal whether an RGB or YUV output is being
used.
Let's remove the inconsistency and allow for the colorspace usage by
renaming the function.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220120151625.594595-2-maxime@cerno.tech
Move the base i915 buddy allocator code into drm
- Move i915_buddy.h to include/drm
- Move i915_buddy.c to drm root folder
- Rename "i915" string with "drm" string wherever applicable
- Rename "I915" string with "DRM" string wherever applicable
- Fix header file dependencies
- Fix alignment issues
- add Makefile support for drm buddy
- export functions and write kerneldoc description
- Remove i915 selftest config check condition as buddy selftest
will be moved to drm selftest folder
cleanup i915 buddy references in i915 driver module
and replace with drm buddy
v2:
- include header file in alphabetical order(Thomas)
- merged changes listed in the body section into a single patch
to keep the build intact(Christian, Jani)
v3:
- make drm buddy a separate module(Thomas, Christian)
v4:
- Fix build error reported by kernel test robot <lkp@intel.com>
- removed i915 buddy selftest from i915_mock_selftests.h to
avoid build error
- removed selftests/i915_buddy.c file as we create a new set of
buddy test cases in drm/selftests folder
v5:
- Fix merge conflict issue
v6:
- replace drm_buddy_mm structure name as drm_buddy(Thomas, Christian)
- replace drm_buddy_alloc() function name as drm_buddy_alloc_blocks()
(Thomas)
- replace drm_buddy_free() function name as drm_buddy_free_block()
(Thomas)
- export drm_buddy_free_block() function
- fix multiple instances of KMEM_CACHE() entry
v7:
- fix warnings reported by kernel test robot <lkp@intel.com>
- modify the license(Christian)
v8:
- fix warnings reported by kernel test robot <lkp@intel.com>
Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220118104504.2349-1-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>
Allow a privacy screen provider to stash its private data pointer in the
drm_privacy_screen, and update the drm_privacy_screen_register() call to
accept that. Also introduce a *_get_drvdata() so that it can retrieved
back when needed.
This also touches the IBM Thinkpad platform driver, the only user of
privacy screen today, to pass NULL for now to the updated API.
Signed-off-by: Rajat Jain <rajatja@google.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220107190208.95479-1-rajatja@google.com
Backmerging for v5.16-rc5. Resolves a conflict between drm-misc-next
and drm-misc-fixes in the vc4 driver.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
There are a few details specific to the GETFB2 IOCTL.
It's not immediately clear how user-space should check for the
number of planes. Suggest using the handles field or the pitches
field.
The modifier array is filled with zeroes, ie. DRM_FORMAT_MOD_LINEAR.
So explicitly tell user-space to not look at it unless the flag is
set.
Changes in v2 (Daniel):
- Mention that handles should be used to compute the number of planes,
and only refer to pitches as a fallback.
- Reword bit about undefined modifier.
Signed-off-by: Simon Ser <contact@emersion.fr>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211123112400.22245-1-contact@emersion.fr
Thomas Zimmermann requested a fixes backmerge, specifically also for
96c5f82ef0 ("drm/vc4: fix error code in vc4_create_object()")
Just a bunch of adjacent changes conflicts, even the big pile of them
in vc4.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Pull char/misc driver fixes from Greg KH:
"Here are a bunch of small char/misc and other driver subsystem fixes.
Included in here are:
- iio driver fixes for reported problems
- phy driver fixes for a number of reported problems
- mhi resume bugfix for broken hardware
- nvmem driver fix
- rtsx driver fix for irq issues
- fastrpc packet parsing fix
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-5.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (33 commits)
bus: mhi: core: Add support for forced PM resume
iio: trigger: stm32-timer: fix MODULE_ALIAS
misc: rtsx: Avoid mangling IRQ during runtime PM
nvmem: eeprom: at25: fix FRAM byte_len
misc: fastrpc: fix improper packet size calculation
MAINTAINERS: add maintainer for Qualcomm FastRPC driver
bus: mhi: pci_generic: Fix device recovery failed issue
iio: adc: stm32: fix null pointer on defer_probe error
phy: HiSilicon: Fix copy and paste bug in error handling
dt-bindings: phy: zynqmp-psgtr: fix USB phy name
phy: ti: omap-usb2: Fix the kernel-doc style
phy: qualcomm: ipq806x-usb: Fix kernel-doc style
iio: at91-sama5d2: Fix incorrect sign extension
iio: adc: axp20x_adc: fix charging current reporting on AXP22x
iio: gyro: adxrs290: fix data signedness
phy: ti: tusb1210: Fix the kernel-doc warn
phy: qualcomm: usb-hsic: Fix the kernel-doc warn
phy: qualcomm: qmp: Add missing struct documentation
phy: mvebu-cp110-utmi: Fix kernel-doc warns
iio: ad7768-1: Call iio_trigger_notify_done() on error
...
Pull percpu fixes from Dennis Zhou:
"This contains a fix for SMP && !MMU archs for percpu which has been
tested by arm and sh. It seems in the past they have gotten away with
it due to mapping of vm functions to km functions, but this fell apart
a few releases ago and was just reported recently.
The other is just a minor dependency clean up.
I think queued up right now by Andrew is a fix in percpu that papers
of what seems to be a bug in hotplug for a special situation with
memoryless nodes. Michal Hocko is digging into it further"
* 'for-5.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
percpu_ref: Replace kernel.h with the necessary inclusions
percpu: km: ensure it is used with NOMMU (either UP or SMP)
Merge misc fixes from Andrew Morton:
"21 patches.
Subsystems affected by this patch series: MAINTAINERS, mailmap, and mm
(mlock, pagecache, damon, slub, memcg, hugetlb, and pagecache)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (21 commits)
mm: bdi: initialize bdi_min_ratio when bdi is unregistered
hugetlbfs: fix issue of preallocation of gigantic pages can't work
mm/memcg: relocate mod_objcg_mlstate(), get_obj_stock() and put_obj_stock()
mm/slub: fix endianness bug for alloc/free_traces attributes
selftests/damon: split test cases
selftests/damon: test debugfs file reads/writes with huge count
selftests/damon: test wrong DAMOS condition ranges input
selftests/damon: test DAMON enabling with empty target_ids case
selftests/damon: skip test if DAMON is running
mm/damon/vaddr-test: remove unnecessary variables
mm/damon/vaddr-test: split a test function having >1024 bytes frame size
mm/damon/vaddr: remove an unnecessary warning message
mm/damon/core: remove unnecessary error messages
mm/damon/dbgfs: remove an unnecessary error message
mm/damon/core: use better timer mechanisms selection threshold
mm/damon/core: fix fake load reports due to uninterruptible sleeps
timers: implement usleep_idle_range()
filemap: remove PageHWPoison check from next_uptodate_page()
mailmap: update email address for Guo Ren
MAINTAINERS: update kdump maintainers
...
Patch series "mm/damon: Fix fake /proc/loadavg reports", v3.
This patchset fixes DAMON's fake load report issue. The first patch
makes yet another variant of usleep_range() for this fix, and the second
patch fixes the issue of DAMON by making it using the newly introduced
function.
This patch (of 2):
Some kernel threads such as DAMON could need to repeatedly sleep in
micro seconds level. Because usleep_range() sleeps in uninterruptible
state, however, such threads would make /proc/loadavg reports fake load.
To help such cases, this commit implements a variant of usleep_range()
called usleep_idle_range(). It is same to usleep_range() but sets the
state of the current task as TASK_IDLE while sleeping.
Link: https://lkml.kernel.org/r/20211126145015.15862-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20211126145015.15862-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This limit has not been updated since 2008, when it was increased to 64
KiB at the request of GnuPG. Until recently, the main use-cases for this
feature were (1) preventing sensitive memory from being swapped, as in
GnuPG's use-case; and (2) real-time use-cases. In the first case, little
memory is called for, and in the second case, the user is generally in a
position to increase it if they need more.
The introduction of IOURING_REGISTER_BUFFERS adds a third use-case:
preparing fixed buffers for high-performance I/O. This use-case will take
as much of this memory as it can get, but is still limited to 64 KiB by
default, which is very little. This increases the limit to 8 MB, which
was chosen fairly arbitrarily as a more generous, but still conservative,
default value.
It is also possible to raise this limit in userspace. This is easily
done, for example, in the use-case of a network daemon: systemd, for
instance, provides for this via LimitMEMLOCK in the service file; OpenRC
via the rc_ulimit variables. However, there is no established userspace
facility for configuring this outside of daemons: end-user applications do
not presently have access to a convenient means of raising their limits.
The buck, as it were, stops with the kernel. It's much easier to address
it here than it is to bring it to hundreds of distributions, and it can
only realistically be relied upon to be high-enough by end-user software
if it is more-or-less ubiquitous. Most distros don't change this
particular rlimit from the kernel-supplied default value, so a change here
will easily provide that ubiquity.
Link: https://lkml.kernel.org/r/20211028080813.15966-1-sir@cmpwn.com
Signed-off-by: Drew DeVault <sir@cmpwn.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Cyril Hrubis <chrubis@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Andrew Dona-Couch <andrew@donacou.ch>
Cc: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull power management fix from Rafael Wysocki:
"Fix a kernedoc comment that doesn't match the behavior of the function
documented by it"
* tag 'pm-5.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: runtime: Fix pm_runtime_active() kerneldoc comment
Pull aio poll fixes from Eric Biggers:
"Fix three bugs in aio poll, and one issue with POLLFREE more broadly:
- aio poll didn't handle POLLFREE, causing a use-after-free.
- aio poll could block while the file is ready.
- aio poll called eventfd_signal() when it isn't allowed.
- POLLFREE didn't handle multiple exclusive waiters correctly.
This has been tested with the libaio test suite, as well as with test
programs I wrote that reproduce the first two bugs. I am sending this
pull request myself as no one seems to be maintaining this code"
* tag 'aio-poll-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux:
aio: Fix incorrect usage of eventfd_signal_allowed()
aio: fix use-after-free due to missing POLLFREE handling
aio: keep poll requests on waitqueue until completed
signalfd: use wake_up_pollfree()
binder: use wake_up_pollfree()
wait: add wake_up_pollfree()
amd-drm-next-5.17-2021-12-02:
amdgpu:
- Use generic drm fb helpers
- PSR fixes
- Rework DCN3.1 clkmgr
- DPCD 1.3 fixes
- Misc display fixes can cleanups
- Clock query fixes for APUs
- LTTPR fixes
- DSC fixes
- Misc PM fixes
- RAS fixes
- OLED backlight fix
- SRIOV fixes
- Add STB (Smart Trace Buffer) for supported dGPUs
- IH rework
- Enable seamless boot for DCN3.01
amdkfd:
- Rework more stuff around IP discovery enumeration
- Further clean up of interfaces with amdgpu
- SVM fixes
radeon:
- Indentation fixes
UAPI:
- Add a new KFD header that defines some of the sysfs bitfields and enums that userspace has been using for a while
The corresponding bit-fields and enums in user mode are defined in
https://github.com/RadeonOpenCompute/ROCT-Thunk-Interface/blob/master/include/hsakmttypes.h
Signed-off-by: Dave Airlie <airlied@redhat.com>
# Conflicts:
# drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
From: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211202191643.5970-1-alexander.deucher@amd.com
When kernel.h is used in the headers it adds a lot into dependency hell,
especially when there are circular dependencies are involved.
Replace kernel.h inclusion with the list of what is really being used.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Pull networking fixes from Jakub Kicinski:
"Including fixes from bpf, can and netfilter.
Current release - regressions:
- bpf, sockmap: re-evaluate proto ops when psock is removed from
sockmap
Current release - new code bugs:
- bpf: fix bpf_check_mod_kfunc_call for built-in modules
- ice: fixes for TC classifier offloads
- vrf: don't run conntrack on vrf with !dflt qdisc
Previous releases - regressions:
- bpf: fix the off-by-two error in range markings
- seg6: fix the iif in the IPv6 socket control block
- devlink: fix netns refcount leak in devlink_nl_cmd_reload()
- dsa: mv88e6xxx: fix "don't use PHY_DETECT on internal PHY's"
- dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports
Previous releases - always broken:
- ethtool: do not perform operations on net devices being
unregistered
- udp: use datalen to cap max gso segments
- ice: fix races in stats collection
- fec: only clear interrupt of handling queue in fec_enet_rx_queue()
- m_can: pci: fix incorrect reference clock rate
- m_can: disable and ignore ELO interrupt
- mvpp2: fix XDP rx queues registering
Misc:
- treewide: add missing includes masked by cgroup -> bpf.h
dependency"
* tag 'net-5.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (82 commits)
net: dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports
net: wwan: iosm: fixes unable to send AT command during mbim tx
net: wwan: iosm: fixes net interface nonfunctional after fw flash
net: wwan: iosm: fixes unnecessary doorbell send
net: dsa: felix: Fix memory leak in felix_setup_mmio_filtering
MAINTAINERS: s390/net: remove myself as maintainer
net/sched: fq_pie: prevent dismantle issue
net: mana: Fix memory leak in mana_hwc_create_wq
seg6: fix the iif in the IPv6 socket control block
nfp: Fix memory leak in nfp_cpp_area_cache_add()
nfc: fix potential NULL pointer deref in nfc_genl_dump_ses_done
nfc: fix segfault in nfc_genl_dump_devices_done
udp: using datalen to cap max gso segments
net: dsa: mv88e6xxx: error handling for serdes_power functions
can: kvaser_usb: get CAN clock frequency from device
can: kvaser_pciefd: kvaser_pciefd_rx_error_frame(): increase correct stats->{rx,tx}_errors counter
net: mvpp2: fix XDP rx queues registering
vmxnet3: fix minimum vectors alloc issue
net, neigh: clear whole pneigh_entry at alloc time
net: dsa: mv88e6xxx: fix "don't use PHY_DETECT on internal PHY's"
...
Pull HID fixes from Jiri Kosina:
- fixes for various drivers which assume that a HID device is on USB
transport, but that might not necessarily be the case, as the device
can be faked by uhid. (Greg, Benjamin Tissoires)
- fix for spurious wakeups on certain Lenovo notebooks (Thomas
Weißschuh)
- a few other device-specific quirks
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid:
HID: Ignore battery for Elan touchscreen on Asus UX550VE
HID: intel-ish-hid: ipc: only enable IRQ wakeup when requested
HID: google: add eel USB id
HID: add USB_HID dependancy to hid-prodikeys
HID: add USB_HID dependancy to hid-chicony
HID: bigbenff: prevent null pointer dereference
HID: sony: fix error path in probe
HID: add USB_HID dependancy on some USB HID drivers
HID: check for valid USB device for many HID drivers
HID: wacom: fix problems when device is not a valid USB device
HID: add hid_is_usb() function to make it simpler for USB detection
HID: quirks: Add quirk for the Microsoft Surface 3 type-cover
signalfd_poll() and binder_poll() are special in that they use a
waitqueue whose lifetime is the current task, rather than the struct
file as is normally the case. This is okay for blocking polls, since a
blocking poll occurs within one task; however, non-blocking polls
require another solution. This solution is for the queue to be cleared
before it is freed, by sending a POLLFREE notification to all waiters.
Unfortunately, only eventpoll handles POLLFREE. A second type of
non-blocking poll, aio poll, was added in kernel v4.18, and it doesn't
handle POLLFREE. This allows a use-after-free to occur if a signalfd or
binder fd is polled with aio poll, and the waitqueue gets freed.
Fix this by making aio poll handle POLLFREE.
A patch by Ramji Jiyani <ramjiyani@google.com>
(https://lore.kernel.org/r/20211027011834.2497484-1-ramjiyani@google.com)
tried to do this by making aio_poll_wake() always complete the request
inline if POLLFREE is seen. However, that solution had two bugs.
First, it introduced a deadlock, as it unconditionally locked the aio
context while holding the waitqueue lock, which inverts the normal
locking order. Second, it didn't consider that POLLFREE notifications
are missed while the request has been temporarily de-queued.
The second problem was solved by my previous patch. This patch then
properly fixes the use-after-free by handling POLLFREE in a
deadlock-free way. It does this by taking advantage of the fact that
freeing of the waitqueue is RCU-delayed, similar to what eventpoll does.
Fixes: 2c14fa838c ("aio: implement IOCB_CMD_POLL")
Cc: <stable@vger.kernel.org> # v4.18+
Link: https://lore.kernel.org/r/20211209010455.42744-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Several ->poll() implementations are special in that they use a
waitqueue whose lifetime is the current task, rather than the struct
file as is normally the case. This is okay for blocking polls, since a
blocking poll occurs within one task; however, non-blocking polls
require another solution. This solution is for the queue to be cleared
before it is freed, using 'wake_up_poll(wq, EPOLLHUP | POLLFREE);'.
However, that has a bug: wake_up_poll() calls __wake_up() with
nr_exclusive=1. Therefore, if there are multiple "exclusive" waiters,
and the wakeup function for the first one returns a positive value, only
that one will be called. That's *not* what's needed for POLLFREE;
POLLFREE is special in that it really needs to wake up everyone.
Considering the three non-blocking poll systems:
- io_uring poll doesn't handle POLLFREE at all, so it is broken anyway.
- aio poll is unaffected, since it doesn't support exclusive waits.
However, that's fragile, as someone could add this feature later.
- epoll doesn't appear to be broken by this, since its wakeup function
returns 0 when it sees POLLFREE. But this is fragile.
Although there is a workaround (see epoll), it's better to define a
function which always sends POLLFREE to all waiters. Add such a
function. Also make it verify that the queue really becomes empty after
all waiters have been woken up.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211209010455.42744-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
