From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- 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