linux/kernel/trace
Zheng Yejian b71645d6af tracing: Fix cpu buffers unavailable due to 'record_disabled' missed
Trace ring buffer can no longer record anything after executing
following commands at the shell prompt:

  # cd /sys/kernel/tracing
  # cat tracing_cpumask
  fff
  # echo 0 > tracing_cpumask
  # echo 1 > snapshot
  # echo fff > tracing_cpumask
  # echo 1 > tracing_on
  # echo "hello world" > trace_marker
  -bash: echo: write error: Bad file descriptor

The root cause is that:
  1. After `echo 0 > tracing_cpumask`, 'record_disabled' of cpu buffers
     in 'tr->array_buffer.buffer' became 1 (see tracing_set_cpumask());
  2. After `echo 1 > snapshot`, 'tr->array_buffer.buffer' is swapped
     with 'tr->max_buffer.buffer', then the 'record_disabled' became 0
     (see update_max_tr());
  3. After `echo fff > tracing_cpumask`, the 'record_disabled' become -1;
Then array_buffer and max_buffer are both unavailable due to value of
'record_disabled' is not 0.

To fix it, enable or disable both array_buffer and max_buffer at the same
time in tracing_set_cpumask().

Link: https://lkml.kernel.org/r/20230805033816.3284594-2-zhengyejian1@huawei.com

Cc: <mhiramat@kernel.org>
Cc: <vnagarnaik@google.com>
Cc: <shuah@kernel.org>
Fixes: 71babb2705 ("tracing: change CPU ring buffer state from tracing_cpumask")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-08-16 15:12:42 -04:00
..
rv tracing/tools: Updates for 6.4 2023-04-28 16:11:26 -07:00
blktrace.c block: remove more NULL checks after bdev_get_queue() 2023-02-21 09:23:22 -07:00
bpf_trace.c bpf: Disable preemption in bpf_event_output 2023-07-25 17:06:37 -07:00
bpf_trace.h
error_report-traces.c
fgraph.c tracing: arm64: Avoid missing-prototype warnings 2023-07-12 12:06:04 -04:00
fprobe.c Probe fixes for 6.5-rc1, the 2nd set: 2023-07-16 12:13:51 -07:00
ftrace_internal.h tracing: arm64: Avoid missing-prototype warnings 2023-07-12 12:06:04 -04:00
ftrace.c ftrace: Fix possible warning on checking all pages used in ftrace_process_locs() 2023-07-12 17:47:37 -04:00
Kconfig Probes updates for v6.5: 2023-06-30 10:44:53 -07:00
kprobe_event_gen_test.c tracing: Fix wrong return in kprobe_event_gen_test.c 2023-03-19 12:20:48 -04:00
Makefile tracing/probes: Add fprobe events for tracing function entry and exit. 2023-06-06 21:39:55 +09:00
pid_list.c
pid_list.h
power-traces.c
preemptirq_delay_test.c
rethook.c Probes fixes and clean ups for v6.5-rc1: 2023-07-12 12:01:16 -07:00
ring_buffer_benchmark.c ring_buffer: Remove unused "event" parameter 2022-11-23 19:08:30 -05:00
ring_buffer.c ring-buffer: Fix kernel-doc warnings in ring_buffer.c 2023-07-28 19:59:03 -04:00
rpm-traces.c
synth_event_gen_test.c tracing: Always use canonical ftrace path 2023-02-18 14:34:09 -05:00
trace_benchmark.c tracing: Add numeric delta time to the trace event benchmark 2022-09-26 13:01:09 -04:00
trace_benchmark.h tracing: Add numeric delta time to the trace event benchmark 2022-09-26 13:01:09 -04:00
trace_boot.c tracing/boot: Test strscpy() against less than zero for error 2023-07-05 10:30:49 -04:00
trace_branch.c
trace_clock.c
trace_dynevent.c tracing: Free buffers when a used dynamic event is removed 2022-11-23 19:07:12 -05:00
trace_dynevent.h
trace_entries.h function_graph: Support recording and printing the return value of function 2023-06-20 18:38:37 -04:00
trace_eprobe.c Probes fixes and clean ups for v6.5-rc1: 2023-07-12 12:01:16 -07:00
trace_event_perf.c tracing/perf: Use strndup_user instead of kzalloc/strncpy_from_user 2022-11-23 19:08:31 -05:00
trace_events_filter_test.h
trace_events_filter.c tracing: Add a way to filter function addresses to function names 2023-01-25 10:31:11 -05:00
trace_events_hist.c tracing/histograms: Return an error if we fail to add histogram to hist_vars list 2023-07-23 11:18:52 -04:00
trace_events_inject.c tracing: Replace all non-returning strlcpy with strscpy 2023-05-26 13:52:19 -07:00
trace_events_synth.c tracing/synthetic: Fix kernel-doc warnings in trace_events_synth.c 2023-07-28 19:59:03 -04:00
trace_events_trigger.c tracing: Fix kernel-doc warnings in trace_events_trigger.c 2023-07-28 19:59:03 -04:00
trace_events_user.c tracing/user_events: Fix struct arg size match check 2023-07-10 21:38:13 -04:00
trace_events.c tracing: Fix warning in trace_buffered_event_disable() 2023-07-28 20:29:51 -04:00
trace_export.c tracing: Fix TASK_COMM_LEN in trace event format file 2023-02-12 10:23:39 -05:00
trace_fprobe.c tracing/probes: Add $arg* meta argument for all function args 2023-06-06 21:39:56 +09:00
trace_functions_graph.c function_graph: Support recording and printing the return value of function 2023-06-20 18:38:37 -04:00
trace_functions.c
trace_hwlat.c tracing/hwlat: Replace sched_setaffinity with set_cpus_allowed_ptr 2023-03-19 13:23:22 -04:00
trace_irqsoff.c
trace_kdb.c
trace_kprobe_selftest.c tracing: arm64: Avoid missing-prototype warnings 2023-07-12 12:06:04 -04:00
trace_kprobe_selftest.h
trace_kprobe.c Probes updates for v6.5: 2023-06-30 10:44:53 -07:00
trace_mmiotrace.c
trace_nop.c
trace_osnoise.c tracing/timerlat: Add user-space interface 2023-06-22 10:39:56 -04:00
trace_output.c Tracing updates for 6.5: 2023-06-30 10:33:17 -07:00
trace_output.h tracing: Add "fields" option to show raw trace event fields 2023-03-29 06:52:08 -04:00
trace_preemptirq.c cpuidle: tracing, preempt: Squash _rcuidle tracing 2023-01-31 15:01:46 +01:00
trace_printk.c
trace_probe_kernel.h tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails 2023-07-14 17:04:58 +09:00
trace_probe_tmpl.h tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails 2023-07-14 17:04:58 +09:00
trace_probe.c tracing/probes: Fix to add NULL check for BTF APIs 2023-07-26 12:53:38 +09:00
trace_probe.h tracing/probes: Add BTF retval type support 2023-06-06 21:39:56 +09:00
trace_recursion_record.c tracing: Use trace_create_file() to simplify creation of tracefs entries 2022-05-26 21:12:52 -04:00
trace_sched_switch.c sched/tracing: Append prev_state to tp args instead 2022-05-12 00:37:11 +02:00
trace_sched_wakeup.c sched/tracing: Append prev_state to tp args instead 2022-05-12 00:37:11 +02:00
trace_selftest_dynamic.c
trace_selftest.c tracing: Have function_graph selftest call cond_resched() 2023-05-28 21:15:46 -04:00
trace_seq.c tracing: Fix kernel-doc warnings in trace_seq.c 2023-07-28 19:59:04 -04:00
trace_stack.c
trace_stat.c
trace_stat.h
trace_synth.h tracing: Allow synthetic events to pass around stacktraces 2023-01-25 10:31:24 -05:00
trace_syscalls.c tracing: Remove unused __bad_type_size() method 2022-11-17 20:21:06 -05:00
trace_uprobe.c Probe fixes for 6.5-rc1, the 2nd set: 2023-07-16 12:13:51 -07:00
trace.c tracing: Fix cpu buffers unavailable due to 'record_disabled' missed 2023-08-16 15:12:42 -04:00
trace.h Probe fixes for 6.5-rc1, the 2nd set: 2023-07-16 12:13:51 -07:00
tracing_map.c tracing: Remove unused variable 'dups' 2022-10-03 12:20:31 -04:00
tracing_map.h tracing: Remove unused extern declaration tracing_map_set_field_descr() 2023-07-23 11:08:14 -04:00