Pull futex updates from Thomas Gleixner:

 - Switch the reference counting to a RCU based per-CPU reference to
   address a performance bottleneck vs the single instance rcuref
   variant

 - Make the futex selftest build on 32-bit architectures which only
   support 64-bit time_t, e.g. RISCV-32

 - Cleanups and improvements in selftests and futex bench

* tag 'locking-futex-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests/futex: Fix spelling mistake "Succeffuly" -> "Successfully"
  selftests/futex: Define SYS_futex on 32-bit architectures with 64-bit time_t
  perf bench futex: Remove support for IMMUTABLE
  selftests/futex: Remove support for IMMUTABLE
  futex: Remove support for IMMUTABLE
  futex: Make futex_private_hash_get() static
  futex: Use RCU-based per-CPU reference counting instead of rcuref_t
  selftests/futex: Adapt the private hash test to RCU related changes

There is a spelling mistake in a ksft_exit_fail_msg() message. Fix it.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250715130627.1907017-1-colin.i.king@gmail.com

The kernel does not provide sys_futex() on 32-bit architectures that do not
support 32-bit time representations, such as riscv32.

As a result, glibc cannot define SYS_futex, causing compilation failures in
tests that rely on this syscall. Define SYS_futex as SYS_futex_time64 in
such cases to ensure successful compilation and compatibility.

Signed-off-by: Cynthia Huang <cynthia@andestech.com>
Signed-off-by: Ben Zong-You Xie <ben717@andestech.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/all/20250710103630.3156130-1-ben717@andestech.com

Testing for the IMMUTABLE part of the futex interface is not needed
after the removal of the interface.

Remove support for IMMUTABLE from the sefltest.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-6-bigeasy@linutronix.de

The auto scaling on create creation used to automatically assign the new
hash because there was the private hash was unused and could be replaced
right away.

This is already racy because if the private hash is in use by a thread
then the visibile resize will be delayed. With the upcoming change to
wait for a RCU grace period before the hash can be assigned, the test
will always fail.

If the reported number of hash buckets is not updated after an
auto scaling event, block on an acquired lock with a timeout. The timeout
is the delay to wait towards a grace period and locking and a locked
pthread_mutex_t ensure that glibc calls into kernel using futex
operation which will assign new private hash if available.
This will retry every 100ms up to 2 seconds in total.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-2-bigeasy@linutronix.de

sys_futex_wait() expects a struct __kernel_timespec pointer for the
timeout, but the provided struct timespec pointer is of type struct
old_timespec32 when compiled for 32-bit architectures, unless they use
64-bit timespecs already.

Make it work for all variants by converting the provided timespec value
into a local struct __kernel_timespec and provide a pointer to it to the
syscall. This is a pointless operation for 64-bit, but this is not a
hotpath operation, so keep it simple.

This fix is based off [1]

Originally-by: Wei Gao <wegao@suse.com>
Signed-off-by: Terry Tritton <terry.tritton@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250704190234.14230-1-terry.tritton@linaro.org
Link: https://lore.kernel.org/all/20231203235117.29677-1-wegao@suse.com/ [1]

futex_numa was never added to the .gitignore file.
Add it.

Fixes: 9140f57c1c13 ("futex,selftests: Add another FUTEX2_NUMA selftest")
Signed-off-by: Terry Tritton <terry.tritton@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/all/20250704103749.10341-1-terry.tritton@linaro.org

The test fails at the MPOL step if multiple nodes are available. The
reason is that mbind() sets the policy but the home_node, which is
retrieved by the futex code, is not set. This causes to retrieve the
current node and with multiple nodes it fails on one of the iterations.

Use numa_set_mempolicy_home_node() to set the expected node.
Use ksft_exit_fail_msg() to fail and exit in order not to confuse ktap.

Fixes: 3163369407baf ("selftests/futex: Add futex_numa_mpol")
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250528085521.1938355-3-bigeasy@linutronix.de

Mark reported that futex_priv_hash fails on ARM64.
It turns out that the command line parsing does not terminate properly
and ends in the default case assuming an invalid option was passed.

Use an int as the return type for getopt().

Closes: https://lore.kernel.org/all/31869a69-063f-44a3-a079-ba71b2506cce@sirena.org.uk/
Fixes: 3163369407baf ("selftests/futex: Add futex_numa_mpol")
Fixes: cda95faef7bcf ("selftests/futex: Add futex_priv_hash")
Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250528085521.1938355-2-bigeasy@linutronix.de

There is a spelling mistake in a fail error message. Fix it.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20250520080657.30726-1-colin.i.king@gmail.com