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/perf/tests/backward-ring-buffer.c | 170 ++++++++++++++++++++++++++++++++ 1 file changed, 170 insertions(+) create mode 100644 tools/perf/tests/backward-ring-buffer.c (limited to 'tools/perf/tests/backward-ring-buffer.c') diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c new file mode 100644 index 000000000..c5e7999f2 --- /dev/null +++ b/tools/perf/tests/backward-ring-buffer.c @@ -0,0 +1,170 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test backward bit in event attribute, read ring buffer from end to + * beginning + */ + +#include +#include +#include "record.h" +#include "tests.h" +#include "debug.h" +#include "parse-events.h" +#include "util/mmap.h" +#include +#include +#include + +#define NR_ITERS 111 + +static void testcase(void) +{ + int i; + + for (i = 0; i < NR_ITERS; i++) { + char proc_name[15]; + + snprintf(proc_name, sizeof(proc_name), "p:%d\n", i); + prctl(PR_SET_NAME, proc_name); + } +} + +static int count_samples(struct evlist *evlist, int *sample_count, + int *comm_count) +{ + int i; + + for (i = 0; i < evlist->core.nr_mmaps; i++) { + struct mmap *map = &evlist->overwrite_mmap[i]; + union perf_event *event; + + perf_mmap__read_init(&map->core); + while ((event = perf_mmap__read_event(&map->core)) != NULL) { + const u32 type = event->header.type; + + switch (type) { + case PERF_RECORD_SAMPLE: + (*sample_count)++; + break; + case PERF_RECORD_COMM: + (*comm_count)++; + break; + default: + pr_err("Unexpected record of type %d\n", type); + return TEST_FAIL; + } + } + perf_mmap__read_done(&map->core); + } + return TEST_OK; +} + +static int do_test(struct evlist *evlist, int mmap_pages, + int *sample_count, int *comm_count) +{ + int err; + char sbuf[STRERR_BUFSIZE]; + + err = evlist__mmap(evlist, mmap_pages); + if (err < 0) { + pr_debug("evlist__mmap: %s\n", + str_error_r(errno, sbuf, sizeof(sbuf))); + return TEST_FAIL; + } + + evlist__enable(evlist); + testcase(); + evlist__disable(evlist); + + err = count_samples(evlist, sample_count, comm_count); + evlist__munmap(evlist); + return err; +} + + +static int test__backward_ring_buffer(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int ret = TEST_SKIP, err, sample_count = 0, comm_count = 0; + char pid[16], sbuf[STRERR_BUFSIZE]; + struct evlist *evlist; + struct evsel *evsel __maybe_unused; + struct parse_events_error parse_error; + struct record_opts opts = { + .target = { + .uses_mmap = true, + }, + .freq = 0, + .mmap_pages = 256, + .default_interval = 1, + }; + + snprintf(pid, sizeof(pid), "%d", getpid()); + pid[sizeof(pid) - 1] = '\0'; + opts.target.tid = opts.target.pid = pid; + + evlist = evlist__new(); + if (!evlist) { + pr_debug("Not enough memory to create evlist\n"); + return TEST_FAIL; + } + + err = evlist__create_maps(evlist, &opts.target); + if (err < 0) { + pr_debug("Not enough memory to create thread/cpu maps\n"); + goto out_delete_evlist; + } + + parse_events_error__init(&parse_error); + /* + * Set backward bit, ring buffer should be writing from end. Record + * it in aux evlist + */ + err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error); + parse_events_error__exit(&parse_error); + if (err) { + pr_debug("Failed to parse tracepoint event, try use root\n"); + ret = TEST_SKIP; + goto out_delete_evlist; + } + + evlist__config(evlist, &opts, NULL); + + err = evlist__open(evlist); + if (err < 0) { + pr_debug("perf_evlist__open: %s\n", + str_error_r(errno, sbuf, sizeof(sbuf))); + goto out_delete_evlist; + } + + ret = TEST_FAIL; + err = do_test(evlist, opts.mmap_pages, &sample_count, + &comm_count); + if (err != TEST_OK) + goto out_delete_evlist; + + if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) { + pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n", + sample_count, comm_count); + goto out_delete_evlist; + } + + evlist__close(evlist); + + err = evlist__open(evlist); + if (err < 0) { + pr_debug("perf_evlist__open: %s\n", + str_error_r(errno, sbuf, sizeof(sbuf))); + goto out_delete_evlist; + } + + err = do_test(evlist, 1, &sample_count, &comm_count); + if (err != TEST_OK) + goto out_delete_evlist; + + ret = TEST_OK; +out_delete_evlist: + evlist__delete(evlist); + return ret; +} + +DEFINE_SUITE("Read backward ring buffer", backward_ring_buffer); -- cgit v1.3.1