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. --- tools/lib/perf/TODO | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 tools/lib/perf/TODO (limited to 'tools/lib/perf/TODO') diff --git a/tools/lib/perf/TODO b/tools/lib/perf/TODO new file mode 100644 index 000000000..e17972869 --- /dev/null +++ b/tools/lib/perf/TODO @@ -0,0 +1,30 @@ +Future ABI changes +================== + +This file collects items that require a libperf ABI bump. Each entry +should describe the current limitation, the desired end state, and the +scope of the change so that a future ABI revision can batch them +together. + +1. Widen struct perf_cpu.cpu from int16_t to int + - Current limit: 32767 CPUs. No architecture exceeds this today + (x86_64 max is 8192, arm64 is 4096), but NR_CPUS limits keep + growing. perf clamps to INT16_MAX in set_max_cpu_num() as a + safety net. + - Code simplification: the int16_t forces defensive truncation + checks at every boundary where a wider CPU index (int from + sample->cpu, al->cpu, etc.) is narrowed into struct perf_cpu. + Without these checks, values > 32767 silently wrap to negative + numbers (two's complement), bypassing bounds validation. + Widening to int eliminates this entire class of silent + truncation bugs and removes the need for the INT16_MAX clamp + in set_max_cpu_num(). + - Scope: struct perf_cpu is embedded everywhere — perf_cpu_map__cpu(), + perf_cpu_map__min(), perf_cpu_map__max(), perf_cpu_map__has(), the + for_each_cpu macros, and all internal callers. The perf_cpu_map + internal array (RC_CHK_ACCESS(map)->map[]) stores struct perf_cpu + directly. Widening changes the struct layout and every function + that returns or accepts struct perf_cpu by value. + - Migration: bump LIBPERF version in libperf.map, audit all + sizeof(struct perf_cpu) assumptions, update perf.data + serialization if needed. -- cgit v1.3.1