"sydm" is a bit name. Let's rename it to the common "sys-dmac".
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/87tu0nz3xr.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
It turns out the optimisation implemented by commit 4f2c3872dd is
totally broken, since all the places that consume hw->dtcs_used for
events other than cycle count are still not expecting it to be sparsely
populated, and fail to read all the relevant DTC counters correctly if
so.
If implemented correctly, the optimisation potentially saves up to 3
register reads per event update, which is reasonably significant for
events targeting a single node, but still not worth a massive amount of
additional code complexity overall. Getting it right within the current
design looks a fair bit more involved than it was ever intended to be,
so let's just make a functional revert which restores the old behaviour
while still backporting easily.
Fixes: 4f2c3872dd ("perf/arm-cmn: Optimise DTC counter accesses")
Reported-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/b41bb4ed7283c3d8400ce5cf5e6ec94915e6750f.1674498637.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
It is possible that the system manufacturer locks down thermal tuning
beyond what is usually done on the given platform. In that case user
space calibration tools should not try to adjust the thermal
configuration of the system.
To allow user space to check if that is the case, add a new sysfs
attribute "production_mode" that will be present when the ACPI DCFG
method is present under the INT3400 device object in the ACPI Namespace.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The drive adjustment register definition of gpio13 and gpio81 is wrong:
"the start address for the range" of gpio18 is corrected to 0x000,
"the start bit for the first register within the range" of gpio81 is
corrected to 24.
Fixes: 6cf5e9ef36 ("pinctrl: add pinctrl driver on mt8195")
Signed-off-by: Guodong Liu <Guodong.Liu@mediatek.com>
Link: https://lore.kernel.org/r/20230118062116.26315-1-Guodong.Liu@mediatek.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Coverity spotted that *buf is not initialized to zero in
mtk_pctrl_dbg_show. Using uninitialized variable *buf as argument to %s
when calling seq_printf. Fix this coverity by initializing *buf as zero.
Fixes: 184d8e13f9 ("pinctrl: mediatek: Add support for pin configuration dump via debugfs.")
Signed-off-by: Guodong Liu <Guodong.Liu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230118062036.26258-3-Guodong.Liu@mediatek.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Coverity spotted that pullen and pullup is not initialized to zero in
mtk_pctrl_show_one_pin. The uninitialized variable pullen is used in
assignment statement "rsel = pullen;" in mtk_pctrl_show_one_pin, and
Uninitialized variable pullup is used when calling scnprintf. Fix this
coverity by initializing pullen and pullup as zero.
Fixes: 184d8e13f9 ("pinctrl: mediatek: Add support for pin configuration dump via debugfs.")
Signed-off-by: Guodong Liu <Guodong.Liu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230118062036.26258-2-Guodong.Liu@mediatek.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Currently, we use the same channel mask for aggregated speakers.
It works fine for playback because we duplicate the audio data for all
aggregated speakers. But we need to get audio data from each aggregated
speaker and combine them to the captured audio. So we need to set
non-overlapping channel mask for aggregated ALH DAIs.
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230125141317.30302-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
The fallback compatible in a list (the last one) cannot be enum, because
it is always fixed. Also if such fallback is used alone ("Generic"
case), it's not a list anymore.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230126100722.9473-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
The corresponding IPC4 module of snd_soc_dapm_buffer widget is module
-to-module copier.
The module-to-module copier is a buffer-like component with demuxing
capabilities.
Rename the host_token_list to common_copier_token_list since it will
be used by host copier and module-to-module copier.
The setup callback is almost the same as sof_ipc4_widget_setup_pcm except
the gtw_cfg data, and the free callback is exactly the same as
sof_ipc4_widget_free_comp_pcm. To reduce the duplication, the commit
reuses the setup and free callbacks.
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230126110637.25542-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Add platform property in sc7280 machine driver bindings for including
platform subnode in dai-links.
This is required for binding the frontend dai driver to do dynamic pcm
routing in ADSP based platforms.
Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@quicinc.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1674468802-14834-3-git-send-email-quic_srivasam@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Update clock name from core to macro in lpass-va-macro node
to make it compatible with existing driver and existing DTS files.
Fixes: 67d99b23c8 ("ASoC: qcom: dt-bindings: add bindings for lpass va macro codec")
Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@quicinc.com>
Reported-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/1674468802-14834-2-git-send-email-quic_srivasam@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This reverts commit 3550bba25d.
No users for this one, revert it for good.
The ->add_pin_ranges() can be used instead.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20230113215352.44272-5-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Yeah, while the ->add_pin_ranges() shouldn't be used by DT drivers,
this one requires it to support quite old firmware descriptions that
do not have gpio-ranges property.
The change allows to clean up GPIO library from OF specifics.
There is no functional change intended.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20230113215352.44272-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The ->add_pin_ranges() is supposed to be called for the backward
compatiblity on Device Tree platforms or non-DT ones. Ensure that
by checking presense of the "gpio-ranges" property.
This allows to clean up a few existing drivers to avoid duplication
of the check.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20230113215352.44272-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Matthieu Baerts says:
====================
mptcp: add mixed v4/v6 support for the in-kernel PM
Before these patches, the in-kernel Path-Manager would not allow, for
the same MPTCP connection, having a mix of subflows in v4 and v6.
MPTCP's RFC 8684 doesn't forbid that and it is even recommended to do so
as the path in v4 and v6 are likely different. Some networks are also
v4 or v6 only, we cannot assume they all have both v4 and v6 support.
Patch 1 then removes this artificial constraint in the in-kernel PM
currently enforcing there are no mixed subflows in place, either in
address announcement or in subflow creation areas.
Patch 2 makes sure the sk_ipv6only attribute is also propagated to
subflows, just in case a new PM wouldn't respect it.
Some selftests have also been added for the in-kernel PM (patch 3).
Patches 4 to 8 are just some cleanups and small improvements in the
printed messages in the userspace PM. It is not linked to the rest but
identified when working on a related patch modifying this selftest,
already in -net:
commit 4656d72c1e ("selftests: mptcp: userspace: validate v4-v6 subflows mix")
---
====================
Link: https://lore.kernel.org/r/20230123-upstream-net-next-pm-v4-v6-v1-0-43fac502bfbf@tessares.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
During the cleanup phase, the server pids were killed with a SIGTERM
directly, not using a SIGUSR1 first to quit safely. As a result, this
test was often ending with two error messages:
read: Connection reset by peer
While at it, use a for-loop to terminate all the PIDs the same way.
Also the different files are now removed after having killed the PIDs
using them. It makes more sense to do that in this order.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Before, only '[FAIL]' was printed in case of error during the validation
phase.
Now, in case of failure, the variable name, its value and expected one
are displayed to help understand what was wrong.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Instead of having a long list of conditions to check, it is possible to
give a list of variable names to compare with their 'e_XXX' version.
This will ease the introduction of the following commit which will print
which condition has failed (if any).
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This script is running a few tests after having setup the environment.
Printing titles helps understand what is being tested.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Like in all other functions in this file, a single point of exit is used
when extra operations are needed: unlock, decrement refcount, etc.
There is no functional change for the moment but it is better to do the
same here to make sure all cleanups are done in case of intermediate
errors.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Note that we can't guess the listener family anymore based on the client
target address: always use IPv6.
The fullmesh flag with endpoints from different families is also
validated here.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Usually, attributes are propagated to subflows as well.
Here, if subflows are created by other ways than the MPTCP path-manager,
it is important to make sure they are in v6 if it is asked by the
userspace.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Currently the in-kernel PM arbitrary enforces that created subflow's
family must match the main MPTCP socket while the RFC allows mixing
IPv4 and IPv6 subflows.
This patch changes the in-kernel PM logic to create subflows matching
the currently selected source (or destination) address. IPv4 sockets
can pick only IPv4 addresses (and v4 mapped in v6), while IPv6 sockets
not restricted to V6ONLY can pick either IPv4 and IPv6 addresses as
long as the source and destination matches.
A helper, previously introduced is used to ease family matching checks,
taking care of IPv4 vs IPv4-mapped-IPv6 vs IPv6 only addresses.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/269
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The bcm2711 has two HDMI outputs, each with their own CEC adapter.
The CEC adapter name has to be unique, but it is currently
hardcoded to "vc4" for both outputs. Change this to use the card_name
from the variant information in order to make the adapter name unique.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 15b4511a4a ("drm/vc4: add HDMI CEC support")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/dcf1db75-d9cc-62cc-fa12-baf1b2b3bf31@xs4all.nl
Now that the i_version counter is reported in struct kstat, there is no
need for this export operation.
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Now that we can call into vfs_getattr to get the i_version field, use
that facility to fetch it instead of doing it in nfsd4_change_attribute.
Neil also pointed out recently that IS_I_VERSION directory operations
are always logged, and so we only need to mitigate the rollback problem
on regular files. Also, we don't need to factor in the ctime when
reexporting NFS or Ceph.
Set the STATX_CHANGE_COOKIE (and BTIME) bits in the request when we're
dealing with a v4 request. Then, instead of looking at IS_I_VERSION when
generating the change attr, look at the result mask and only use it if
STATX_CHANGE_COOKIE is set.
Change nfsd4_change_attribute to only factor in the ctime if it's a
regular file and the fs doesn't advertise STATX_ATTR_CHANGE_MONOTONIC.
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
This is a pretty big function for inlining. Move it to being
non-inlined.
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
When getattr requests the STX_CHANGE_COOKIE, request the full gamut of
caps (similarly to how ctime is handled). When the change attribute
seems to be valid, return it in the change_cookie field and set the flag
in the reply mask. Also, unconditionally enable
STATX_ATTR_CHANGE_MONOTONIC.
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Allow NFS to report the i_version in getattr requests. Since the cost to
fetch it is relatively cheap, do it unconditionally and just set the
flag if it looks like it's valid. Also, conditionally enable the
MONOTONIC flag when the server reports its change attr type as such.
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
The NFS server has a lot of special handling for different types of
change attribute access, depending on the underlying filesystem. In
most cases, it's doing a getattr anyway and then fetching that value
after the fact.
Rather that do that, add a new STATX_CHANGE_COOKIE flag that is a
kernel-only symbol (for now). If requested and getattr can implement it,
it can fill out this field. For IS_I_VERSION inodes, add a generic
implementation in vfs_getattr_nosec. Take care to mask
STATX_CHANGE_COOKIE off in requests from userland and in the result
mask.
Since not all filesystems can give the same guarantees of monotonicity,
claim a STATX_ATTR_CHANGE_MONOTONIC flag that filesystems can set to
indicate that they offer an i_version value that can never go backward.
Eventually if we decide to make the i_version available to userland, we
can just designate a field for it in struct statx, and move the
STATX_CHANGE_COOKIE definition to the uapi header.
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
The i_version field in the kernel has had different semantics over
the decades, but NFSv4 has certain expectations. Update the comments
in iversion.h to describe when the i_version must change.
Cc: Colin Walters <walters@verbum.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Trond Myklebust <trondmy@hammerspace.com>
Cc: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Add the Verdin Yavia Carrier-Board that exists for both Verdin iMX8M
Plus and Verdin iMX8M Mini.
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Use generic "mcu" node name for rave-sp node, as recommended by
Devicetree specification.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Add DH electronics DHCOM PDK2, PicoITX and DRC02 boards
for the DHCOM i.MX6ULL SoM.
Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
imx6ulz is derived SoC from imx6ull.
Currently, the boards based on imx6ulz are correctly recognized only if
the compatible includes "fsl,imx6ull", while "fsl,imx6ulz" is ignored.
Signed-off-by: Pierluigi Passaro <pierluigi.p@variscite.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Split the source codes related with CQ handling into a new function.
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://lore.kernel.org/r/20230116193502.66540-5-yanjun.zhu@intel.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Split the source codes related with QP handling into a new function.
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://lore.kernel.org/r/20230116193502.66540-4-yanjun.zhu@intel.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
In the function irdma_reg_user_mr, the mr allocation and free
will be used by other functions. As such, the source codes related
with mr allocation and free are split into the new functions.
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://lore.kernel.org/r/20230116193502.66540-3-yanjun.zhu@intel.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
The source codes related with IRDMA_MEMREG_TYPE_MEM are split
into a new function irdma_reg_user_mr_type_mem.
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://lore.kernel.org/r/20230116193502.66540-2-yanjun.zhu@intel.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
__acpi_{acquire,release}_global_lock(). x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after CMPXCHG
(and related MOV instruction in front of CMPXCHG).
Also, try_cmpxchg() implicitly assigns old *ptr value to "old" when CMPXCHG
fails. There is no need to re-read the value in the loop.
Note that the value from *ptr should be read using READ_ONCE() to prevent
the compiler from merging, refetching or reordering the read.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20230116162522.4072-1-ubizjak@gmail.com
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
set_page_memtype. x86 CMPXCHG instruction returns success in ZF flag,
so this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).
Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg
fails. There is no need to re-read the value in the loop.
Note that the value from *ptr should be read using READ_ONCE to prevent
the compiler from merging, refetching or reordering the read.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230116163446.4734-1-ubizjak@gmail.com
The previous patch has disabled preemption in all the down_read() and
up_read() code paths. For symmetry, this patch extends commit:
48dfb5d256 ("locking/rwsem: Disable preemption while trying for rwsem lock")
... to have preemption disabled in all the down_write() and up_write()
code paths, including downgrade_write().
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126003628.365092-4-longman@redhat.com
Commit:
91d2a812df ("locking/rwsem: Make handoff writer optimistically spin on owner")
... assumes that when the owner field is changed to NULL, the lock will
become free soon. But commit:
48dfb5d256 ("locking/rwsem: Disable preemption while trying for rwsem lock")
... disabled preemption when acquiring rwsem for write.
However, preemption has not yet been disabled when acquiring a read lock
on a rwsem. So a reader can add a RWSEM_READER_BIAS to count without
setting owner to signal a reader, got preempted out by a RT task which
then spins in the writer slowpath as owner remains NULL leading to live lock.
One easy way to fix this problem is to disable preemption at all the
down_read*() and up_read() code paths as implemented in this patch.
Fixes: 91d2a812df ("locking/rwsem: Make handoff writer optimistically spin on owner")
Reported-by: Mukesh Ojha <quic_mojha@quicinc.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126003628.365092-3-longman@redhat.com
A non-first waiter can potentially spin in the for loop of
rwsem_down_write_slowpath() without sleeping but fail to acquire the
lock even if the rwsem is free if the following sequence happens:
Non-first RT waiter First waiter Lock holder
------------------- ------------ -----------
Acquire wait_lock
rwsem_try_write_lock():
Set handoff bit if RT or
wait too long
Set waiter->handoff_set
Release wait_lock
Acquire wait_lock
Inherit waiter->handoff_set
Release wait_lock
Clear owner
Release lock
if (waiter.handoff_set) {
rwsem_spin_on_owner(();
if (OWNER_NULL)
goto trylock_again;
}
trylock_again:
Acquire wait_lock
rwsem_try_write_lock():
if (first->handoff_set && (waiter != first))
return false;
Release wait_lock
A non-first waiter cannot really acquire the rwsem even if it mistakenly
believes that it can spin on OWNER_NULL value. If that waiter happens
to be an RT task running on the same CPU as the first waiter, it can
block the first waiter from acquiring the rwsem leading to live lock.
Fix this problem by making sure that a non-first waiter cannot spin in
the slowpath loop without sleeping.
Fixes: d257cc8cb8 ("locking/rwsem: Make handoff bit handling more consistent")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230126003628.365092-2-longman@redhat.com
Kuninori Morimoto