linux/kernel/trace
Steven Rostedt ef7f38df89 tracing: Do not register unsupported perf events
Synthetic events currently do not have a function to register perf events.
This leads to calling the tracepoint register functions with a NULL
function pointer which triggers:

 ------------[ cut here ]------------
 WARNING: kernel/tracepoint.c:175 at tracepoint_add_func+0x357/0x370, CPU#2: perf/2272
 Modules linked in: kvm_intel kvm irqbypass
 CPU: 2 UID: 0 PID: 2272 Comm: perf Not tainted 6.18.0-ftest-11964-ge022764176fc-dirty #323 PREEMPTLAZY
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
 RIP: 0010:tracepoint_add_func+0x357/0x370
 Code: 28 9c e8 4c 0b f5 ff eb 0f 4c 89 f7 48 c7 c6 80 4d 28 9c e8 ab 89 f4 ff 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc <0f> 0b 49 c7 c6 ea ff ff ff e9 ee fe ff ff 0f 0b e9 f9 fe ff ff 0f
 RSP: 0018:ffffabc0c44d3c40 EFLAGS: 00010246
 RAX: 0000000000000001 RBX: ffff9380aa9e4060 RCX: 0000000000000000
 RDX: 000000000000000a RSI: ffffffff9e1d4a98 RDI: ffff937fcf5fd6c8
 RBP: 0000000000000001 R08: 0000000000000007 R09: ffff937fcf5fc780
 R10: 0000000000000003 R11: ffffffff9c193910 R12: 000000000000000a
 R13: ffffffff9e1e5888 R14: 0000000000000000 R15: ffffabc0c44d3c78
 FS:  00007f6202f5f340(0000) GS:ffff93819f00f000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055d3162281a8 CR3: 0000000106a56003 CR4: 0000000000172ef0
 Call Trace:
  <TASK>
  tracepoint_probe_register+0x5d/0x90
  synth_event_reg+0x3c/0x60
  perf_trace_event_init+0x204/0x340
  perf_trace_init+0x85/0xd0
  perf_tp_event_init+0x2e/0x50
  perf_try_init_event+0x6f/0x230
  ? perf_event_alloc+0x4bb/0xdc0
  perf_event_alloc+0x65a/0xdc0
  __se_sys_perf_event_open+0x290/0x9f0
  do_syscall_64+0x93/0x7b0
  ? entry_SYSCALL_64_after_hwframe+0x76/0x7e
  ? trace_hardirqs_off+0x53/0xc0
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

Instead, have the code return -ENODEV, which doesn't warn and has perf
error out with:

 # perf record -e synthetic:futex_wait
Error:
The sys_perf_event_open() syscall returned with 19 (No such device) for event (synthetic:futex_wait).
"dmesg | grep -i perf" may provide additional information.

Ideally perf should support synthetic events, but for now just fix the
warning. The support can come later.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://patch.msgid.link/20251216182440.147e4453@gandalf.local.home
Fixes: 4b147936fa ("tracing: Add support for 'synthetic' events")
Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-12-17 15:47:35 -05:00
..
rv rv: Convert to use __free 2025-12-02 07:28:32 +01:00
blktrace.c tracing updates for v6.19: 2025-12-05 09:51:37 -08:00
bpf_trace.c bpf: make kprobe_multi_link_prog_run always_inline 2025-11-29 09:47:10 -08:00
bpf_trace.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
error_report-traces.c
fgraph.c tracing: Fix typo in fpgraph.c 2025-12-05 15:43:39 -05:00
fprobe.c tracing fixes for v6.19: 2025-12-06 13:49:40 -08:00
ftrace.c tracing updates for v6.19: 2025-12-05 09:51:37 -08:00
ftrace_internal.h function_graph: Make fgraph_update_pid_func() a stub for !DYNAMIC_FTRACE 2024-06-10 18:08:23 -04:00
Kconfig tracing updates for v6.19: 2025-12-05 09:51:37 -08:00
kprobe_event_gen_test.c
Makefile ftrace: Allow tracing of some of the tracing code 2025-11-26 15:13:30 -05:00
pid_list.c trace/pid_list: optimize pid_list->lock contention 2025-11-13 15:15:54 -05:00
pid_list.h trace/pid_list: optimize pid_list->lock contention 2025-11-13 15:15:54 -05:00
power-traces.c PM: cpufreq: powernv/tracing: Move powernv_throttle trace event 2025-07-21 16:40:56 -04:00
preemptirq_delay_test.c kernel: trace: preemptirq_delay_test: use offstack cpu mask 2025-07-08 18:17:38 -04:00
rethook.c rethook: honor CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING in rethook_try_get() 2024-05-01 23:18:48 +09:00
ring_buffer.c tracing: Fix multiple typos in ring_buffer.c 2025-12-05 15:43:40 -05:00
ring_buffer_benchmark.c tracing: Fix typo in ring_buffer_benchmark.c 2025-12-05 15:43:40 -05:00
rpm-traces.c
synth_event_gen_test.c tracing / synthetic: Disable events after testing in synth_event_gen_test_init() 2023-12-21 10:04:45 -05:00
trace.c tracing: Fix multiple typos in trace.c 2025-12-05 15:43:40 -05:00
trace.h ftrace fixes for v6.19: 2025-12-05 10:13:04 -08:00
trace_benchmark.c tracing: Improve benchmark test performance by using do_div() 2024-05-13 20:00:57 -04:00
trace_benchmark.h
trace_boot.c
trace_branch.c tracing: branch: Use trace_tracing_is_on_cpu() instead of "disabled" field 2025-05-09 15:19:10 -04:00
trace_btf.c tracing/probes: Fix to search structure fields correctly 2024-02-17 21:25:42 +09:00
trace_btf.h
trace_clock.c tracing: Use atomic64_inc_return() in trace_clock_counter() 2024-10-09 19:59:49 -04:00
trace_dynevent.c tracing: Report wrong dynamic event command 2025-11-10 19:26:14 -05:00
trace_dynevent.h tracing: probes: Fix a possible race in trace_probe_log APIs 2025-05-13 22:23:34 +09:00
trace_entries.h function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously 2025-11-26 15:13:30 -05:00
trace_eprobe.c Probes for v6.19 2025-12-05 10:55:47 -08:00
trace_event_perf.c perf: Remove unnecessary parameter of security check 2025-02-26 14:13:58 -05:00
trace_events.c tracing: Do not register unsupported perf events 2025-12-17 15:47:35 -05:00
trace_events_filter.c tracing: Fix typo in trace_events_filter.c 2025-12-05 15:43:40 -05:00
trace_events_filter_test.h
trace_events_hist.c tracing: Fix typo in trace_events_hist.c 2025-12-05 15:43:40 -05:00
trace_events_inject.c tracing: Have format file honor EVENT_FILE_FL_FREED 2024-08-07 18:12:46 -04:00
trace_events_synth.c tracing: Fix fixed array of synthetic event 2025-12-05 15:38:10 -05:00
trace_events_trigger.c tracing: Fix typo in trace_events_trigger.c 2025-12-05 15:43:41 -05:00
trace_events_user.c tracing: Fix multiple typos in trace_events_user.c 2025-12-05 15:43:41 -05:00
trace_export.c
trace_fprobe.c tracing updates for v6.19: 2025-12-05 09:51:37 -08:00
trace_functions.c tracing: Have function tracer define options per instance 2025-11-12 09:59:54 -05:00
trace_functions_graph.c ftrace fixes for v6.19: 2025-12-05 10:13:04 -08:00
trace_hwlat.c tracing: Replace opencoded cpumask_next_wrap() in move_to_next_cpu() 2025-07-08 18:17:29 -04:00
trace_irqsoff.c tracing: Allow tracer to add more than 32 options 2025-11-04 21:44:00 +09:00
trace_kdb.c tracing: Allow tracer to add more than 32 options 2025-11-04 21:44:00 +09:00
trace_kprobe.c tracing: Allow tracer to add more than 32 options 2025-11-04 21:44:00 +09:00
trace_kprobe_selftest.c
trace_kprobe_selftest.h
trace_mmiotrace.c tracing/mmiotrace: Remove reference to unused per CPU data pointer 2025-05-08 09:36:09 -04:00
trace_nop.c
trace_osnoise.c tracing: Fix multiple typos in trace_osnoise.c 2025-12-05 15:43:41 -05:00
trace_output.c tracing updates for v6.19: 2025-12-05 09:51:37 -08:00
trace_output.h tracing: Allow tracer to add more than 32 options 2025-11-04 21:44:00 +09:00
trace_preemptirq.c tracing: Fix archs that still call tracepoints without RCU watching 2024-12-05 09:28:58 -05:00
trace_printk.c
trace_probe.c tracing fixes for v6.19: 2025-12-06 13:49:40 -08:00
trace_probe.h tracing: probes: Use __free() for trace_probe_log 2025-11-01 01:10:28 +09:00
trace_probe_kernel.h
trace_probe_tmpl.h tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS 2024-12-26 10:50:04 -05:00
trace_recursion_record.c
trace_sched_switch.c tracing: Ensure optimized hashing works 2025-09-30 17:27:58 -04:00
trace_sched_wakeup.c tracing: Allow tracer to add more than 32 options 2025-11-04 21:44:00 +09:00
trace_selftest.c fgraph: Pass ftrace_regs to retfunc 2024-12-26 10:50:03 -05:00
trace_selftest_dynamic.c
trace_seq.c tracing: Fix typo in trace_seq.c 2025-12-05 15:43:41 -05:00
trace_stack.c tracing updates for v6.16: 2025-05-29 21:04:36 -07:00
trace_stat.c tracing: Switch trace_stat.c code over to use guard() 2024-12-26 10:38:37 -05:00
trace_stat.h
trace_synth.h
trace_syscalls.c tracing: Hide __NR_utimensat and _NR_mq_timedsend when not defined 2025-11-10 14:23:53 -05:00
trace_uprobe.c tracing: uprobe: eprobes: Allocate traceprobe_parse_context per probe 2025-11-01 01:10:29 +09:00
tracing_map.c tracing: Use vmalloc_array() to improve code 2025-09-23 09:31:58 -04:00
tracing_map.h