From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- include/asm-generic/futex.h | 123 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 123 insertions(+) create mode 100644 include/asm-generic/futex.h (limited to 'include/asm-generic/futex.h') diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h new file mode 100644 index 000000000..fbbcfd801 --- /dev/null +++ b/include/asm-generic/futex.h @@ -0,0 +1,123 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_GENERIC_FUTEX_H +#define _ASM_GENERIC_FUTEX_H + +#include +#include +#include + +#ifndef futex_atomic_cmpxchg_inatomic +#ifndef CONFIG_SMP +/* + * The following implementation only for uniprocessor machines. + * It relies on preempt_disable() ensuring mutual exclusion. + * + */ +#define futex_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval) \ + futex_atomic_cmpxchg_inatomic_local(uval, uaddr, oldval, newval) +#define arch_futex_atomic_op_inuser(op, oparg, oval, uaddr) \ + futex_atomic_op_inuser_local(op, oparg, oval, uaddr) +#endif /* CONFIG_SMP */ +#endif + +/** + * futex_atomic_op_inuser_local() - Atomic arithmetic operation with constant + * argument and comparison of the previous + * futex value with another constant. + * + * @op: operation to execute + * @oparg: argument of the operation + * @oval: previous value at @uaddr on successful return + * @uaddr: pointer to user space address + * + * Return: + * 0 - On success + * -EFAULT - User access resulted in a page fault + * -EAGAIN - Atomic operation was unable to complete due to contention + * -ENOSYS - Operation not supported + */ +static inline int +futex_atomic_op_inuser_local(int op, u32 oparg, int *oval, u32 __user *uaddr) +{ + int oldval, ret; + u32 tmp; + + preempt_disable(); + + ret = -EFAULT; + if (unlikely(get_user(oldval, uaddr) != 0)) + goto out_pagefault_enable; + + ret = 0; + tmp = oldval; + + switch (op) { + case FUTEX_OP_SET: + tmp = oparg; + break; + case FUTEX_OP_ADD: + tmp += oparg; + break; + case FUTEX_OP_OR: + tmp |= oparg; + break; + case FUTEX_OP_ANDN: + tmp &= ~oparg; + break; + case FUTEX_OP_XOR: + tmp ^= oparg; + break; + default: + ret = -ENOSYS; + } + + if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) + ret = -EFAULT; + +out_pagefault_enable: + preempt_enable(); + + if (ret == 0) + *oval = oldval; + + return ret; +} + +/** + * futex_atomic_cmpxchg_inatomic_local() - Compare and exchange the content of the + * uaddr with newval if the current value is + * oldval. + * @uval: pointer to store content of @uaddr + * @uaddr: pointer to user space address + * @oldval: old value + * @newval: new value to store to @uaddr + * + * Return: + * 0 - On success + * -EFAULT - User access resulted in a page fault + * -EAGAIN - Atomic operation was unable to complete due to contention + */ +static inline int +futex_atomic_cmpxchg_inatomic_local(u32 *uval, u32 __user *uaddr, + u32 oldval, u32 newval) +{ + u32 val; + + preempt_disable(); + if (unlikely(get_user(val, uaddr) != 0)) { + preempt_enable(); + return -EFAULT; + } + + if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { + preempt_enable(); + return -EFAULT; + } + + *uval = val; + preempt_enable(); + + return 0; +} + +#endif -- cgit v1.3.1