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Masami Hiramatsu 60baabc37b ring_buffer: tracing: Inherit the tracing setting to next ring buffer 
commit 73c8d89455 upstream.

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>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-08-09 12:16:38 +02:00
..
bpf bpf: fix references to free_bpf_prog_info() in comments 2018-08-03 07:50:37 +02:00
cgroup cgroup: fix rule checking for threaded mode switching 2018-03-28 18:24:37 +02:00
configs ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES. 2017-08-22 18:43:23 -07:00
debug kdb: make "mdr" command repeat 2018-05-30 07:52:41 +02:00
events perf/core: Fix perf_output_read_group() 2018-05-30 07:52:34 +02:00
gcov License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq genirq: Make force irq threading setup more robust 2018-08-09 12:16:38 +02:00
livepatch License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
locking locking/percpu-rwsem: Annotate rwsem ownership transfer by setting RWSEM_OWNER_UNKNOWN 2018-06-21 04:03:00 +09:00
power PM / wakeup: Make s2idle_lock a RAW_SPINLOCK 2018-08-03 07:50:29 +02:00
printk printk: drop in_nmi check from printk_safe_flush_on_panic() 2018-08-03 07:50:24 +02:00
rcu rcu: Call touch_nmi_watchdog() while printing stall warnings 2018-05-30 07:52:39 +02:00
sched sched/core: Require cpu_active() in select_task_rq(), for user tasks 2018-07-08 15:30:53 +02:00
time nohz: Fix local_timer_softirq_pending() 2018-08-09 12:16:38 +02:00
trace ring_buffer: tracing: Inherit the tracing setting to next ring buffer 2018-08-09 12:16:38 +02:00
.gitignore
acct.c kernel/acct.c: fix the acct->needcheck check in check_free_space() 2018-01-10 09:31:17 +01:00
async.c kernel/async.c: revert "async: simplify lowest_in_progress()" 2018-02-16 20:23:05 +01:00
audit.c audit: return on memory error to avoid null pointer dereference 2018-05-30 07:52:39 +02:00
audit.h ipc: mqueue: Replace timespec with timespec64 2017-09-03 20:21:24 -04:00
audit_fsnotify.c
audit_tree.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
audit_watch.c audit/stable-4.13 PR 20170816 2017-08-16 16:48:34 -07:00
auditfilter.c audit: allow not equal op for audit by executable 2018-08-03 07:50:39 +02:00
auditsc.c audit: fix potential null dereference 'context->module.name' 2018-08-06 16:20:49 +02:00
backtracetest.c
bounds.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
capability.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat.c compat: fix 4-byte infoleak via uninitialized struct field 2018-05-16 10:10:26 +02:00
configs.c
context_tracking.c
cpu.c timers: Reinitialize per cpu bases on hotplug 2018-01-02 20:31:15 +01:00
cpu_pm.c
crash_core.c kdump: write correct address of mem_section into vmcoreinfo 2018-01-17 09:45:27 +01:00
crash_dump.c
cred.c
delayacct.c delayacct: Use raw_spinlocks 2018-08-03 07:50:38 +02:00
dma.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
elfcore.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
exec_domain.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
exit.c kernel/exit.c: export abort() to modules 2018-02-13 10:19:49 +01:00
extable.c extable: Enable RCU if it is not watching in kernel_text_address() 2017-09-23 16:50:20 -04:00
fork.c fork: unconditionally clear stack on fork 2018-08-03 07:50:20 +02:00
freezer.c
futex.c futex: Fix OWNER_DEAD fixup 2018-02-03 17:38:47 +01:00
futex_compat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
groups.c kernel: make groups_sort calling a responsibility group_info allocators 2017-12-20 10:10:18 +01:00
hung_task.c kernel/hung_task.c: show all hung tasks before panic 2018-08-03 07:50:23 +02:00
irq_work.c
jump_label.c jump_label: Invoke jump_label_test() via early_initcall() 2017-12-14 09:53:13 +01:00
kallsyms.c
kcmp.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c kcov: ensure irq code sees a valid area 2018-08-03 07:50:22 +02:00
kexec.c
kexec_core.c
kexec_file.c
kexec_internal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kmod.c kmod: move #ifdef CONFIG_MODULES wrapper to Makefile 2017-09-08 18:26:51 -07:00
kprobes.c kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y 2017-12-10 13:40:40 +01:00
ksysfs.c
kthread.c kthread, tracing: Don't expose half-written comm when creating kthreads 2018-08-03 07:50:21 +02:00
latencytop.c
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
memremap.c mm: Fix memory size alignment in devm_memremap_pages_release() 2018-02-22 15:42:27 +01:00
module-internal.h
module.c init: fix false positives in W+X checking 2018-06-21 04:02:57 +09:00
module_signing.c
notifier.c
nsproxy.c
padata.c
panic.c locking/refcounts, x86/asm: Implement fast refcount overflow protection 2017-08-17 10:40:26 +02:00
params.c kernel/params.c: improve STANDARD_PARAM_DEF readability 2017-10-03 17:54:26 -07:00
pid.c pids: make task_tgid_nr_ns() safe 2017-08-21 12:47:31 -07:00
pid_namespace.c
profile.c
ptrace.c
range.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c
relay.c kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE 2018-05-30 07:52:00 +02:00
resource.c resource: fix integer overflow at reallocation 2018-04-24 09:36:22 +02:00
seccomp.c seccomp: Move speculation migitation control to arch code 2018-05-22 18:54:04 +02:00
signal.c sched/core: Introduce set_special_state() 2018-06-21 04:02:54 +09:00
smp.c treewide: make "nr_cpu_ids" unsigned 2017-09-08 18:26:48 -07:00
smpboot.c watchdog/core, powerpc: Lock cpus across reconfiguration 2017-10-04 10:53:54 +02:00
smpboot.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
softirq.c nohz: Fix missing tick reprogram when interrupting an inline softirq 2018-08-09 12:16:38 +02:00
stacktrace.c
stop_machine.c stop_machine: Use raw spinlocks 2018-08-03 07:50:38 +02:00
sys.c kernel/sys.c: fix potential Spectre v1 issue 2018-05-30 07:51:50 +02:00
sys_ni.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sysctl.c kmemcheck: rip it out 2018-02-22 15:42:24 +01:00
sysctl_binary.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
task_work.c locking/barriers: Convert users of lockless_dereference() to READ_ONCE() 2017-12-25 14:26:21 +01:00
taskstats.c
test_kprobes.c
torture.c
tracepoint.c tracepoint: Do not warn on ENOMEM 2018-05-09 09:51:50 +02:00
tsacct.c
ucount.c
uid16.c kernel: make groups_sort calling a responsibility group_info allocators 2017-12-20 10:10:18 +01:00
umh.c kmod: split out umh code into its own file 2017-09-08 18:26:50 -07:00
up.c smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
watchdog.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
watchdog_hld.c Merge branch 'linus' into core/urgent, to pick up dependent commits 2017-11-04 08:53:04 +01:00
workqueue.c workqueue: use put_device() instead of kfree() 2018-05-30 07:52:14 +02:00
workqueue_internal.h Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2017-11-06 12:26:49 -08:00