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Frederic Weisbecker f3b9aae162 tracing/ring-buffer: Add unlock recursion protection on discard 
The pair of helpers trace_recursive_lock() and trace_recursive_unlock()
have been introduced recently to provide generic tracing recursion
protection.

They are used in a symetric way:

 - trace_recursive_lock() on buffer reserve
 - trace_recursive_unlock() on buffer commit

However sometimes, we don't commit but discard on entry
to the buffer, ie: in case of filter checking.

Then we must also unlock the recursion protection on discard time,
otherwise the tracing gets definitely deactivated and a warning
is raised spuriously, such as:

111.119821] ------------[ cut here ]------------
[  111.119829] WARNING: at kernel/trace/ring_buffer.c:1498 ring_buffer_lock_reserve+0x1b7/0x1d0()
[  111.119835] Hardware name: AMILO Li 2727
[  111.119839] Modules linked in:
[  111.119846] Pid: 5731, comm: Xorg Tainted: G        W  2.6.30-rc1 #69
[  111.119851] Call Trace:
[  111.119863]  [<ffffffff8025ce68>] warn_slowpath+0xd8/0x130
[  111.119873]  [<ffffffff8028a30f>] ? __lock_acquire+0x19f/0x1ae0
[  111.119882]  [<ffffffff8028a30f>] ? __lock_acquire+0x19f/0x1ae0
[  111.119891]  [<ffffffff802199b0>] ? native_sched_clock+0x20/0x70
[  111.119899]  [<ffffffff80286dee>] ? put_lock_stats+0xe/0x30
[  111.119906]  [<ffffffff80286eb8>] ? lock_release_holdtime+0xa8/0x150
[  111.119913]  [<ffffffff802c8ae7>] ring_buffer_lock_reserve+0x1b7/0x1d0
[  111.119921]  [<ffffffff802cd110>] trace_buffer_lock_reserve+0x30/0x70
[  111.119930]  [<ffffffff802ce000>] trace_current_buffer_lock_reserve+0x20/0x30
[  111.119939]  [<ffffffff802474e8>] ftrace_raw_event_sched_switch+0x58/0x100
[  111.119948]  [<ffffffff808103b7>] __schedule+0x3a7/0x4cd
[  111.119957]  [<ffffffff80211b56>] ? ftrace_call+0x5/0x2b
[  111.119964]  [<ffffffff80211b56>] ? ftrace_call+0x5/0x2b
[  111.119971]  [<ffffffff80810c08>] schedule+0x18/0x40
[  111.119977]  [<ffffffff80810e09>] preempt_schedule+0x39/0x60
[  111.119985]  [<ffffffff80813bd3>] _read_unlock+0x53/0x60
[  111.119993]  [<ffffffff807259d2>] sock_def_readable+0x72/0x80
[  111.120002]  [<ffffffff807ad5ed>] unix_stream_sendmsg+0x24d/0x3d0
[  111.120011]  [<ffffffff807219a3>] sock_aio_write+0x143/0x160
[  111.120019]  [<ffffffff80211b56>] ? ftrace_call+0x5/0x2b
[  111.120026]  [<ffffffff80721860>] ? sock_aio_write+0x0/0x160
[  111.120033]  [<ffffffff80721860>] ? sock_aio_write+0x0/0x160
[  111.120042]  [<ffffffff8031c283>] do_sync_readv_writev+0xf3/0x140
[  111.120049]  [<ffffffff80211b56>] ? ftrace_call+0x5/0x2b
[  111.120057]  [<ffffffff80276ff0>] ? autoremove_wake_function+0x0/0x40
[  111.120067]  [<ffffffff8045d489>] ? cap_file_permission+0x9/0x10
[  111.120074]  [<ffffffff8045c1e6>] ? security_file_permission+0x16/0x20
[  111.120082]  [<ffffffff8031cab4>] do_readv_writev+0xd4/0x1f0
[  111.120089]  [<ffffffff80211b56>] ? ftrace_call+0x5/0x2b
[  111.120097]  [<ffffffff80211b56>] ? ftrace_call+0x5/0x2b
[  111.120105]  [<ffffffff8031cc18>] vfs_writev+0x48/0x70
[  111.120111]  [<ffffffff8031cd65>] sys_writev+0x55/0xc0
[  111.120119]  [<ffffffff80211e32>] system_call_fastpath+0x16/0x1b
[  111.120125] ---[ end trace 15605f4e98d5ccb5 ]---

[ Impact: fix spurious warning triggering tracing shutdown ]

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2009-04-20 10:59:20 +02:00
..
blktrace.c blktrace: fix context-info when mixed-using blk tracer and trace events 2009-04-16 10:11:01 +02:00
ftrace.c ftrace: use module notifier for function tracer 2009-04-17 16:59:15 +02:00
Kconfig Merge branch 'linus' into tracing/core 2009-04-14 00:02:22 +02:00
kmemtrace.c tracing/filters: use ring_buffer_discard_commit() in filter_check_discard() 2009-04-14 00:00:56 +02:00
Makefile tracing/events: move the ftrace event tracing code to core 2009-04-14 12:57:59 -04:00
ring_buffer.c tracing/ring-buffer: Add unlock recursion protection on discard 2009-04-20 10:59:20 +02:00
trace.c tracing: protect trace_printk from recursion 2009-04-17 16:21:35 -04:00
trace.h tracing/filters: add filter_mutex to protect filter predicates 2009-04-17 18:28:27 +02:00
trace_boot.c tracing: use macros to denote usec and nsec per second 2009-04-07 14:43:06 +02:00
trace_branch.c tracing/filters: use ring_buffer_discard_commit() in filter_check_discard() 2009-04-14 00:00:56 +02:00
trace_clock.c tracing: fix four sparse warnings 2009-03-22 18:16:54 +01:00
trace_event_profile.c tracing/events: convert event call sites to use a link list 2009-04-14 12:58:00 -04:00
trace_event_types.h tracing/filters: add TRACE_EVENT_FORMAT_NOFILTER event macro 2009-04-14 00:00:51 +02:00
trace_events.c tracing/filters: add filter_mutex to protect filter predicates 2009-04-17 18:28:27 +02:00
trace_events_filter.c tracing/filters: add filter_mutex to protect filter predicates 2009-04-17 18:28:27 +02:00
trace_export.c tracing/filters: allow on-the-fly filter switching 2009-04-14 00:03:55 +02:00
trace_functions.c tracing/core: use appropriate waiting on trace_pipe 2009-02-18 01:40:20 +01:00
trace_functions_graph.c function-graph: add option to calculate graph time or not 2009-03-24 23:41:11 -04:00
trace_hw_branches.c tracing/filters: use ring_buffer_discard_commit() in filter_check_discard() 2009-04-14 00:00:56 +02:00
trace_irqsoff.c tracing: have latency tracers set the latency format 2009-03-04 22:15:30 -05:00
trace_mmiotrace.c tracing: use macros to denote usec and nsec per second 2009-04-07 14:43:06 +02:00
trace_nop.c tracing/ftrace: make nop-tracer use polling wait for events on pipe 2009-03-23 09:22:15 +01:00
trace_output.c tracing/events: add export symbols for trace events in modules 2009-04-14 12:58:01 -04:00
trace_output.h tracing/events: move declarations from trace directory to core include 2009-04-14 12:57:58 -04:00
trace_power.c tracing/filters: use ring_buffer_discard_commit() in filter_check_discard() 2009-04-14 00:00:56 +02:00
trace_printk.c tracing/ftrace: factorize the tracing files creation 2009-04-07 14:43:07 +02:00
trace_sched_switch.c tracing/events: move trace point headers into include/trace/events 2009-04-14 22:05:43 -04:00
trace_sched_wakeup.c tracing/events: move trace point headers into include/trace/events 2009-04-14 22:05:43 -04:00
trace_selftest.c tracing: keep the tracing buffer after self-test failure 2009-03-22 15:17:21 +01:00
trace_selftest_dynamic.c ftrace: fix dynamic ftrace selftest 2008-05-23 21:13:23 +02:00
trace_stack.c tracing/ftrace: factorize the tracing files creation 2009-04-07 14:43:07 +02:00
trace_stat.c Merge branch 'linus' into tracing/core 2009-04-07 13:47:45 +02:00
trace_stat.h tracing: add handler to trace_stat 2009-03-24 23:22:58 -04:00
trace_syscalls.c tracing/syscalls: use a dedicated file header 2009-04-09 05:43:32 +02:00
trace_sysprof.c tracing/ftrace: factorize the tracing files creation 2009-04-07 14:43:07 +02:00
trace_workqueue.c Merge branch 'linus' into tracing/core 2009-04-07 13:47:45 +02:00