Merge branch 'next' into for-linus

Prepare input updates for 6.6 merge window.

Merge tag 'v6.4' into next

Sync up with mainline to bring in updates to shared infrastructure.

Merge drm/drm-next into drm-misc-next-fixes

Backmerging to sync drm-misc-next-fixes with drm-misc-next.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge branch 'drm-next' of git://anongit.freedesktop.org/drm/drm into msm-next-lumag-base

Merge the drm-next tree to pick up the DRM DSC helpers (merged via
drm-intel-next tree). MSM DSC v1.2 patche

Merge branch 'drm-next' of git://anongit.freedesktop.org/drm/drm into msm-next-lumag-base

Merge the drm-next tree to pick up the DRM DSC helpers (merged via
drm-intel-next tree). MSM DSC v1.2 patches depend on these helpers.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

show more ...

Merge tag 'v6.4-rc4' into wpan-next/staging

Linux 6.4-rc4

Merge drm/drm-next into drm-intel-gt-next

For conflict avoidance we need the following commit:

c9a9f18d3ad8 drm/i915/huc: use const struct bus_type pointers

Signed-off-by: Tvrtko Ursulin <tvrtko

Merge drm/drm-next into drm-intel-gt-next

For conflict avoidance we need the following commit:

c9a9f18d3ad8 drm/i915/huc: use const struct bus_type pointers

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

show more ...

Merge drm/drm-next into drm-intel-next

Backmerge to get some hwmon dependencies.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Merge drm/drm-fixes into drm-misc-fixes

Let's bring 6.4-rc1 in drm-misc-fixes to start the new fix cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge drm/drm-next into drm-misc-next

Start the 6.5 release cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge branch 'next' into for-linus

Prepare input updates for 6.4 merge window.

Merge branch 'for-6.4/amd-sfh' into for-linus

- assorted functional fixes for amd-sfh driver (Basavaraj Natikar)

Merge tag 'lkmm.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull Linux Kernel Memory Model updates from Paul McKenney
"This improves LKMM diagnostic messages, un

Merge tag 'lkmm.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull Linux Kernel Memory Model updates from Paul McKenney
"This improves LKMM diagnostic messages, unifies handling of the
ordering produced by unlock/lock pairs, adds support for the
smp_mb__after_srcu_read_unlock() macro, removes redundant members from
the to-r relation, brings SRCU read-side semantics into alignment with
Linux-kernel SRCU, makes ppo a subrelation of po, and improves
documentation"

* tag 'lkmm.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
Documentation: litmus-tests: Correct spelling
tools/memory-model: Add documentation about SRCU read-side critical sections
tools/memory-model: Make ppo a subrelation of po
tools/memory-model: Provide exact SRCU semantics
tools/memory-model: Restrict to-r to read-read address dependency
tools/memory-model: Add smp_mb__after_srcu_read_unlock()
tools/memory-model: Unify UNLOCK+LOCK pairings to po-unlock-lock-po
tools/memory-model: Update some warning labels

show more ...

Merge drm/drm-next into drm-intel-gt-next

Need to pull in commit from drm-next (earlier in drm-intel-next):

1eca0778f4b3 ("drm/i915: add struct i915_dsm to wrap dsm members together")

In order to

Merge drm/drm-next into drm-intel-gt-next

Need to pull in commit from drm-next (earlier in drm-intel-next):

1eca0778f4b3 ("drm/i915: add struct i915_dsm to wrap dsm members together")

In order to merge following patch to drm-intel-gt-next:

https://patchwork.freedesktop.org/patch/530942/?series=114925&rev=6

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

show more ...

Merge drm/drm-next into drm-intel-next

Catch up with 6.3-rc cycle...

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

tools/memory-model: Provide exact SRCU semantics

LKMM has long provided only approximate handling of SRCU read-side
critical sections. This has not been a pressing problem because LKMM's
traditiona

tools/memory-model: Provide exact SRCU semantics

LKMM has long provided only approximate handling of SRCU read-side
critical sections. This has not been a pressing problem because LKMM's
traditional handling is correct for the common cases of non-overlapping
and properly nested critical sections. However, LKMM's traditional
handling of partially overlapping critical sections incorrectly fuses
them into one large critical section.

For example, consider the following litmus test:

------------------------------------------------------------------------

C C-srcu-nest-5

(*
* Result: Sometimes
*
* This demonstrates non-nested overlapping of SRCU read-side critical
* sections. Unlike RCU, SRCU critical sections do not unconditionally
* nest.
*)

{}

P0(int *x, int *y, struct srcu_struct *s1)
{
int r1;
int r2;
int r3;
int r4;

r3 = srcu_read_lock(s1);
r2 = READ_ONCE(*y);
r4 = srcu_read_lock(s1);
srcu_read_unlock(s1, r3);
r1 = READ_ONCE(*x);
srcu_read_unlock(s1, r4);
}

P1(int *x, int *y, struct srcu_struct *s1)
{
WRITE_ONCE(*y, 1);
synchronize_srcu(s1);
WRITE_ONCE(*x, 1);
}

locations [0:r1]
exists (0:r1=1 /\ 0:r2=0)

------------------------------------------------------------------------

Current mainline incorrectly flattens the two critical sections into
one larger critical section, giving "Never" instead of the correct
"Sometimes":

------------------------------------------------------------------------

$ herd7 -conf linux-kernel.cfg C-srcu-nest-5.litmus
Test C-srcu-nest-5 Allowed
States 3
0:r1=0; 0:r2=0;
0:r1=0; 0:r2=1;
0:r1=1; 0:r2=1;
No
Witnesses
Positive: 0 Negative: 3
Flag srcu-bad-nesting
Condition exists (0:r1=1 /\ 0:r2=0)
Observation C-srcu-nest-5 Never 0 3
Time C-srcu-nest-5 0.01
Hash=e692c106cf3e84e20f12991dc438ff1b

------------------------------------------------------------------------

To its credit, it does complain about bad nesting. But with this
commit we get the following result, which has the virtue of being
correct:

------------------------------------------------------------------------

$ herd7 -conf linux-kernel.cfg C-srcu-nest-5.litmus
Test C-srcu-nest-5 Allowed
States 4
0:r1=0; 0:r2=0;
0:r1=0; 0:r2=1;
0:r1=1; 0:r2=0;
0:r1=1; 0:r2=1;
Ok
Witnesses
Positive: 1 Negative: 3
Condition exists (0:r1=1 /\ 0:r2=0)
Observation C-srcu-nest-5 Sometimes 1 3
Time C-srcu-nest-5 0.05
Hash=e692c106cf3e84e20f12991dc438ff1b

------------------------------------------------------------------------

In addition, there are new srcu_down_read() and srcu_up_read()
functions on their way to mainline. Roughly speaking, these are to
srcu_read_lock() and srcu_read_unlock() as down() and up() are to
mutex_lock() and mutex_unlock(). The key point is that
srcu_down_read() can execute in one process and the matching
srcu_up_read() in another, as shown in this litmus test:

------------------------------------------------------------------------

C C-srcu-nest-6

(*
* Result: Never
*
* This would be valid for srcu_down_read() and srcu_up_read().
*)

{}

P0(int *x, int *y, struct srcu_struct *s1, int *idx, int *f)
{
int r2;
int r3;

r3 = srcu_down_read(s1);
WRITE_ONCE(*idx, r3);
r2 = READ_ONCE(*y);
smp_store_release(f, 1);
}

P1(int *x, int *y, struct srcu_struct *s1, int *idx, int *f)
{
int r1;
int r3;
int r4;

r4 = smp_load_acquire(f);
r1 = READ_ONCE(*x);
r3 = READ_ONCE(*idx);
srcu_up_read(s1, r3);
}

P2(int *x, int *y, struct srcu_struct *s1)
{
WRITE_ONCE(*y, 1);
synchronize_srcu(s1);
WRITE_ONCE(*x, 1);
}

locations [0:r1]
filter (1:r4=1)
exists (1:r1=1 /\ 0:r2=0)

------------------------------------------------------------------------

When run on current mainline, this litmus test gets a complaint about
an unknown macro srcu_down_read(). With this commit:

------------------------------------------------------------------------

herd7 -conf linux-kernel.cfg C-srcu-nest-6.litmus
Test C-srcu-nest-6 Allowed
States 3
0:r1=0; 0:r2=0; 1:r1=0;
0:r1=0; 0:r2=1; 1:r1=0;
0:r1=0; 0:r2=1; 1:r1=1;
No
Witnesses
Positive: 0 Negative: 3
Condition exists (1:r1=1 /\ 0:r2=0)
Observation C-srcu-nest-6 Never 0 3
Time C-srcu-nest-6 0.02
Hash=c1f20257d052ca5e899be508bedcb2a1

------------------------------------------------------------------------

Note that the user must supply the flag "f" and the "filter" clause,
similar to what must be done to emulate call_rcu().

The commit works by treating srcu_read_lock()/srcu_down_read() as
loads and srcu_read_unlock()/srcu_up_read() as stores. This allows us
to determine which unlock matches which lock by looking for a data
dependency between them. In order for this to work properly, the data
dependencies have to be tracked through stores to intermediate
variables such as "idx" in the litmus test above; this is handled by
the new carry-srcu-data relation. But it's important here (and in the
existing carry-dep relation) to avoid tracking the dependencies
through SRCU unlock stores. Otherwise, in situations resembling:

A: r1 = srcu_read_lock(s);
B: srcu_read_unlock(s, r1);
C: r2 = srcu_read_lock(s);
D: srcu_read_unlock(s, r2);

it would look as if D was dependent on both A and C, because "s" would
appear to be an intermediate variable written by B and read by C.
This explains the complications in the definitions of carry-srcu-dep
and carry-dep.

As a debugging aid, the commit adds a check for errors in which the
value returned by one call to srcu_read_lock()/srcu_down_read() is
passed to more than one instance of srcu_read_unlock()/srcu_up_read().

Finally, since these SRCU-related primitives are now treated as
ordinary reads and writes, we have to add them into the lists of
marked accesses (i.e., not subject to data races) and lock-related
accesses (i.e., one shouldn't try to access an srcu_struct with a
non-lock-related primitive such as READ_ONCE() or a plain write).

Portions of this approach were suggested by Boqun Feng and Jonas
Oberhauser.

[ paulmck: Fix space-before-tab whitespace nit. ]

Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

show more ...

tools/memory-model: Add smp_mb__after_srcu_read_unlock()

This commit adds support for smp_mb__after_srcu_read_unlock(), which,
when combined with a prior srcu_read_unlock(), implies a full memory
ba

tools/memory-model: Add smp_mb__after_srcu_read_unlock()

This commit adds support for smp_mb__after_srcu_read_unlock(), which,
when combined with a prior srcu_read_unlock(), implies a full memory
barrier. No ordering is guaranteed to accesses between the two, and
placing accesses between is bad practice in any case.

Tests may be found at https://github.com/paulmckrcu/litmus in files
matching manual/kernel/C-srcu-mb-*.litmus.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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tools/memory-model: Update some warning labels

Some of the warning labels used in the LKMM are unfortunately
ambiguous. In particular, the same warning is used for both an
unmatched rcu_read_lock()

tools/memory-model: Update some warning labels

Some of the warning labels used in the LKMM are unfortunately
ambiguous. In particular, the same warning is used for both an
unmatched rcu_read_lock() call and for an unmatched rcu_read_unlock()
call. Likewise for the srcu_* equivalents. Also, the warning about
passing a wrong value to srcu_read_unlock() -- i.e., a value different
from the one returned by the matching srcu_read_lock() -- talks about
bad nesting rather than non-matching values.

Let's update the warning labels to make their meanings more clear.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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Merge remote-tracking branch 'drm/drm-next' into msm-next

Merge drm-next into msm-next to pick up external clk and PM dependencies
for improved a6xx GPU reset sequence.

Signed-off-by: Rob Clark <ro

Merge remote-tracking branch 'drm/drm-next' into msm-next

Merge drm-next into msm-next to pick up external clk and PM dependencies
for improved a6xx GPU reset sequence.

Signed-off-by: Rob Clark <robdclark@chromium.org>

show more ...

Merge tag 'v6.3-rc2' into next

Merge with mainline to get of_property_present() and other newer APIs.

Merge drm/drm-fixes into drm-misc-fixes

Backmerging to get latest upstream.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge drm/drm-next into drm-misc-next

Backmerging to get v6.3-rc1 and sync with the other DRM trees.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge remote-tracking branch 'acme/perf-tools' into perf-tools-next

To pick up perf-tools fixes just merged upstream.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Merge tag 'lkmm.2023.02.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull LKMM (Linux Kernel Memory Model) updates from Paul McKenney:
"Documentation updates.

Add read

Merge tag 'lkmm.2023.02.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull LKMM (Linux Kernel Memory Model) updates from Paul McKenney:
"Documentation updates.

Add read-modify-write sequences, which means that stronger primitives
more consistently result in stronger ordering, while still remaining
in the envelope of the hardware that supports Linux.

Address, data, and control dependencies used to ignore data that was
stored in temporaries. This update extends these dependency chains to
include unmarked intra-thread stores and loads. Note that these
unmarked stores and loads should not be concurrently accessed from
multiple threads, and doing so will cause LKMM to flag such accesses
as data races"

* tag 'lkmm.2023.02.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
tools: memory-model: Make plain accesses carry dependencies
Documentation: Fixed a typo in atomic_t.txt
tools: memory-model: Add rmw-sequences to the LKMM
locking/memory-barriers.txt: Improve documentation for writel() example

show more ...

tools: memory-model: Make plain accesses carry dependencies

As reported by Viktor, plain accesses in LKMM are weaker than
accesses to registers: the latter carry dependencies but the former
do not.

tools: memory-model: Make plain accesses carry dependencies

As reported by Viktor, plain accesses in LKMM are weaker than
accesses to registers: the latter carry dependencies but the former
do not. This is exemplified in the following snippet:

int r = READ_ONCE(*x);
WRITE_ONCE(*y, r);

Here a data dependency links the READ_ONCE() to the WRITE_ONCE(),
preserving their order, because the model treats r as a register.
If r is turned into a memory location accessed by plain accesses,
however, the link is broken and the order between READ_ONCE() and
WRITE_ONCE() is no longer preserved.

This is too conservative, since any optimizations on plain
accesses that might break dependencies are also possible on
registers; it also contradicts the intuitive notion of "dependency"
as the data stored by the WRITE_ONCE() does depend on the data read
by the READ_ONCE(), independently of whether r is a register or a
memory location.

This is resolved by redefining all dependencies to include
dependencies carried by memory accesses; a dependency is said to be
carried by memory accesses (in the model: carry-dep) from one load
to another load if the initial load is followed by an arbitrarily
long sequence alternating between stores and loads of the same
thread, where the data of each store depends on the previous load,
and is read by the next load.

Any dependency linking the final load in the sequence to another
access also links the initial load in the sequence to that access.

More deep details can be found in this LKML discussion:

https://lore.kernel.org/lkml/d86295788ad14a02874ab030ddb8a6f8@huawei.com/

Reported-by: Viktor Vafeiadis <viktor@mpi-sws.org>
Signed-off-by: Jonas Oberhauser <jonas.oberhauser@huawei.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

show more ...

Merge branch 'next' into for-linus

Prepare input updates for 5.4 merge window.