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linux/kernel/trace
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Frederic Weisbecker 4903620034 tracing/ftrace: stop {irqs, preempt}soff tracers when tracing is stopped 
Impact: fix a selftest warning

In some cases, it's possible to see the following warning on irqsoff
tracer selftest:

[    4.640003] Testing tracer irqsoff: <4>------------[ cut here ]------------
[    4.653562] WARNING: at kernel/trace/trace.c:458 update_max_tr_single+0x9a/0xc4()
[    4.660000] Hardware name: System Product Name
[    4.660000] Modules linked in:
[    4.660000] Pid: 301, comm: kstop/1 Not tainted 2.6.29-rc8-tip #35837
[    4.660000] Call Trace:
[    4.660000]  [<4014b588>] warn_slowpath+0x79/0x8f
[    4.660000]  [<402d6949>] ? put_dec+0x64/0x6b
[    4.660000]  [<40162b56>] ? getnstimeofday+0x58/0xdd
[    4.660000]  [<40162210>] ? clocksource_read+0x3/0xf
[    4.660000]  [<4015eb44>] ? ktime_set+0x8/0x34
[    4.660000]  [<4014101a>] ? balance_runtime+0x8/0x56
[    4.660000]  [<405f6f11>] ? _spin_lock+0x3/0x10
[    4.660000]  [<4011f643>] ? ftrace_call+0x5/0x8
[    4.660000]  [<4015d0f1>] ? task_cputime_zero+0x3/0x27
[    4.660000]  [<40190ee7>] ? cpupri_set+0x90/0xcb
[    4.660000]  [<405f7208>] ? _spin_lock_irqsave+0x22/0x34
[    4.660000]  [<40190f12>] ? cpupri_set+0xbb/0xcb
[    4.660000]  [<405f7151>] ? _spin_unlock_irqrestore+0x23/0x35
[    4.660000]  [<4018493f>] ? ring_buffer_reset_cpu+0x27/0x51
[    4.660000]  [<405f7208>] ? _spin_lock_irqsave+0x22/0x34
[    4.660000]  [<40184962>] ? ring_buffer_reset_cpu+0x4a/0x51
[    4.660000]  [<405f7151>] ? _spin_unlock_irqrestore+0x23/0x35
[    4.660000]  [<4018cc29>] ? trace_hardirqs_off+0x1a/0x1c
[    4.660000]  [<405f7151>] ? _spin_unlock_irqrestore+0x23/0x35
[    4.660000]  [<40184962>] ? ring_buffer_reset_cpu+0x4a/0x51
[    4.660000]  [<401850f3>] ? cpumask_next+0x15/0x18
[    4.660000]  [<4018a41f>] update_max_tr_single+0x9a/0xc4
[    4.660000]  [<4014e5fe>] ? exit_notify+0x16/0xf2
[    4.660000]  [<4018cd13>] check_critical_timing+0xcc/0x11e
[    4.660000]  [<4014e5fe>] ? exit_notify+0x16/0xf2
[    4.660000]  [<4014e5fe>] ? exit_notify+0x16/0xf2
[    4.660000]  [<4018cdf1>] stop_critical_timing+0x8c/0x9f
[    4.660000]  [<4014e5c4>] ? forget_original_parent+0xac/0xd0
[    4.660000]  [<4018ce3a>] trace_hardirqs_on+0x1a/0x1c
[    4.660000]  [<4014e5c4>] forget_original_parent+0xac/0xd0
[    4.660000]  [<4014e5fe>] exit_notify+0x16/0xf2
[    4.660000]  [<4014e8a5>] do_exit+0x1cb/0x225
[    4.660000]  [<4015c72b>] ? kthread+0x0/0x69
[    4.660000]  [<4011f61d>] kernel_thread_helper+0xd/0x10
[    4.660000] ---[ end trace a7919e7f17c0a725 ]---
[    4.660164] .. no entries found ..FAILED!

During the selftest of irqsoff tracer, we do that:

	/* disable interrupts for a bit */
	local_irq_disable();
	udelay(100);
	local_irq_enable();
	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);

If a callsite performs a new max delay with irqs off just after
tracing_stop, update_max_tr_single() -> ring_buffer_swap_cpu()
will be called with the buffers disabled by tracing_stop(), hence
the warning, then ring_buffer_swap_cpu() return -EAGAIN and
update_max_tr_single() complains.

Fix it by also stopping the tracer before stopping the tracing globally.
A similar situation can happen with preemptoff and preemptirqsoff tracers
where we apply the same fix.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237325938-5240-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-18 10:12:38 +01:00
..
blktrace.c tracing: protect reader of cmdline output 2009-03-16 23:27:06 -04:00
events.c tracing: use generic __stringify 2009-03-10 00:35:05 -04:00
ftrace.c tracing/ftrace: fix the check on nopped sites 2009-03-16 22:15:36 -04:00
Kconfig tracing/syscalls: select kallsysms 2009-03-16 09:13:17 +01:00
kmemtrace.c
Makefile tracing/ftrace: syscall tracing infrastructure, basics 2009-03-13 06:25:43 +01:00
ring_buffer.c ring-buffer: add api to allow a tracer to change clock source 2009-03-17 23:06:31 -04:00
trace_boot.c
trace_branch.c tracing: remove funky whitespace in the trace code 2009-03-10 14:13:14 -04:00
trace_clock.c trace_clock: fix preemption bug 2009-03-10 20:03:01 +01:00
trace_event_types.h tracing: make bprint event use the proper event id 2009-03-12 21:15:00 -04:00
trace_events_stage_1.h tracing: update comments to match event code macros 2009-03-10 13:12:58 -04:00
trace_events_stage_2.h tracing: show event name in trace for TRACE_EVENT created events 2009-03-12 22:00:19 -04:00
trace_events_stage_3.h tracing: remove funky whitespace in the trace code 2009-03-10 14:13:14 -04:00
trace_events.c tracing: fix leak in event_format_read() 2009-03-17 08:38:23 +01:00
trace_export.c tracing: remove funky whitespace in the trace code 2009-03-10 14:13:14 -04:00
trace_functions_graph.c tracing: protect reader of cmdline output 2009-03-16 23:27:06 -04:00
trace_functions.c
trace_hw_branches.c tracing/hw-branch-tracing: convert bts-tracer mutex to a spinlock 2009-02-25 09:16:01 +01:00
trace_irqsoff.c tracing: have latency tracers set the latency format 2009-03-04 22:15:30 -05:00
trace_mmiotrace.c tracing/core: bring back raw trace_printk for dynamic formats strings 2009-03-12 21:15:00 -04:00
trace_nop.c
trace_output.c tracing: protect reader of cmdline output 2009-03-16 23:27:06 -04:00
trace_output.h tracing/core: drop the old trace_printk() implementation in favour of trace_bprintk() 2009-03-06 17:59:12 +01:00
trace_power.c tracing: make power tracer start/stop methods lighter weight 2009-03-17 23:12:11 -04:00
trace_printk.c tracing: export trace formats to user space 2009-03-12 21:15:01 -04:00
trace_sched_switch.c tracing: make sched_switch stop/start light weight 2009-03-17 23:10:45 -04:00
trace_sched_wakeup.c tracing: have latency tracers set the latency format 2009-03-04 22:15:30 -05:00
trace_selftest_dynamic.c
trace_selftest.c tracing/ftrace: stop {irqs, preempt}soff tracers when tracing is stopped 2009-03-18 10:12:38 +01:00
trace_stack.c tracing: left align location header in stack_trace 2009-03-13 00:00:58 -04:00
trace_stat.c
trace_stat.h
trace_syscalls.c tracing/syscalls: protect thread flag toggling from races 2009-03-16 09:13:16 +01:00
trace_sysprof.c tracing: make all file_operations const 2009-03-05 21:46:40 -05:00
trace_workqueue.c tracing: Don't use tracing_record_cmdline() in workqueue tracer fix 2009-03-12 21:23:47 -04:00
trace.c Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace 2009-03-18 06:59:56 +01:00
trace.h Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace 2009-03-18 06:59:56 +01:00