kernel_optimize_test/kernel/trace
Masami Hiramatsu 73c8d89455 ring_buffer: tracing: Inherit the tracing setting to next ring buffer
Maintain the tracing on/off setting of the ring_buffer when switching
to the trace buffer snapshot.

Taking a snapshot is done by swapping the backup ring buffer
(max_tr_buffer). But since the tracing on/off setting is defined
by the ring buffer, when swapping it, the tracing on/off setting
can also be changed. This causes a strange result like below:

  /sys/kernel/debug/tracing # cat tracing_on
  1
  /sys/kernel/debug/tracing # echo 0 > tracing_on
  /sys/kernel/debug/tracing # cat tracing_on
  0
  /sys/kernel/debug/tracing # echo 1 > snapshot
  /sys/kernel/debug/tracing # cat tracing_on
  1
  /sys/kernel/debug/tracing # echo 1 > snapshot
  /sys/kernel/debug/tracing # cat tracing_on
  0

We don't touch tracing_on, but snapshot changes tracing_on
setting each time. This is an anomaly, because user doesn't know
that each "ring_buffer" stores its own tracing-enable state and
the snapshot is done by swapping ring buffers.

Link: http://lkml.kernel.org/r/153149929558.11274.11730609978254724394.stgit@devbox

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Hiraku Toyooka <hiraku.toyooka@cybertrust.co.jp>
Cc: stable@vger.kernel.org
Fixes: debdd57f51 ("tracing: Make a snapshot feature available from userspace")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ Updated commit log and comment in the code ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-07-25 10:29:41 -04:00
..
blktrace.c blktrace: fix trace mutex deadlock 2017-11-27 12:03:58 -07:00
bpf_trace.c bpf: guard bpf_get_current_cgroup_id() with CONFIG_CGROUPS 2018-06-04 21:52:26 +02:00
ftrace.c ftrace: Nuke clear_ftrace_function 2018-07-03 18:33:19 -04:00
Kconfig docs: Fix some broken references 2018-06-15 18:10:01 -03:00
Makefile Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
power-traces.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ring_buffer_benchmark.c ring-buffer: Have ring_buffer_alloc_read_page() return error on offline CPU 2017-08-02 14:23:02 -04:00
ring_buffer.c ring_buffer: tracing: Inherit the tracing setting to next ring buffer 2018-07-25 10:29:41 -04:00
rpm-traces.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_benchmark.c rcu: Rename cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs() 2018-05-15 10:27:29 -07:00
trace_benchmark.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_branch.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_clock.c tracing: Hide global trace clock from lockdep 2018-04-06 08:56:52 -04:00
trace_entries.h tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_event_perf.c perf/core: Fix perf_uprobe_init() 2018-04-10 07:33:10 +02:00
trace_events_filter_test.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_events_filter.c tracing: Make create_filter() code match the comments 2018-07-03 18:14:40 -04:00
trace_events_hist.c tracing: Avoid string overflow 2018-07-03 18:14:39 -04:00
trace_events_trigger.c tracing: Fix double free of event_trigger_data 2018-07-25 10:29:24 -04:00
trace_events.c tracing: Do not show filter file for ftrace internal events 2018-05-29 08:28:46 -04:00
trace_export.c tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_functions_graph.c tracing: Fix missing return symbol in function_graph output 2018-07-03 18:47:11 -04:00
trace_functions.c tracing: Update stack trace skipping for ORC unwinder 2018-01-23 15:57:00 -05:00
trace_hwlat.c trace: make trace_hwlat timestamp y2038 safe 2017-05-08 17:15:15 -07:00
trace_irqsoff.c tracing: Add support for preempt and irq enable/disable events 2017-10-10 18:58:43 -04:00
trace_kdb.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_kprobe.c tracing/kprobe: Release kprobe print_fmt properly 2018-07-11 15:50:52 -04:00
trace_mmiotrace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_nop.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_output.c tracing: Reorder display of TGID to be after PID 2018-07-12 19:56:25 -04:00
trace_output.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_printk.c treewide: Align function definition open/close braces 2018-03-26 11:13:09 +02:00
trace_probe.c tracing: probeevent: Fix to support minus offset from symbol 2018-03-23 12:02:37 -04:00
trace_probe.h Merge branch 'perf/urgent' into perf/core 2018-03-29 16:03:48 +02:00
trace_sched_switch.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_sched_wakeup.c Merge branch 'linus' into sched/core, to pick up fixes 2017-11-08 10:17:15 +01:00
trace_selftest_dynamic.c ftrace: Mark function tracer test functions noinline/noclone 2018-01-23 15:57:29 -05:00
trace_selftest.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_seq.c tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
trace_stack.c tracing: Fix the file mode of stack tracer 2018-05-03 11:58:05 -04:00
trace_stat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_stat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_syscalls.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_uprobe.c bpf: introduce bpf subcommand BPF_TASK_FD_QUERY 2018-05-24 18:18:19 -07:00
trace.c ring_buffer: tracing: Inherit the tracing setting to next ring buffer 2018-07-25 10:29:41 -04:00
trace.h tracing: Optimize trace_buffer_iter() logic 2018-07-03 18:23:33 -04:00
tracing_map.c treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
tracing_map.h tracing: Add per-element variable support to tracing_map 2018-03-10 16:05:53 -05:00