Xiao Yang 0026e356e5 tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation ...

commit 0bbe7f7199 upstream.

Traced event can trigger 'snapshot' operation(i.e. calls snapshot_trigger()
or snapshot_count_trigger()) when register_snapshot_trigger() has completed
registration but doesn't allocate buffer for 'snapshot' event trigger.  In
the rare case, 'snapshot' operation always detects the lack of allocated
buffer so make register_snapshot_trigger() allocate buffer first.

trigger-snapshot.tc in kselftest reproduces the issue on slow vm:
-----------------------------------------------------------
cat trace
...
ftracetest-3028  [002] ....   236.784290: sched_process_fork: comm=ftracetest pid=3028 child_comm=ftracetest child_pid=3036
     <...>-2875  [003] ....   240.460335: tracing_snapshot_instance_cond: *** SNAPSHOT NOT ALLOCATED ***
     <...>-2875  [003] ....   240.460338: tracing_snapshot_instance_cond: *** stopping trace here!   ***
-----------------------------------------------------------

Link: http://lkml.kernel.org/r/20200414015145.66236-1-yangx.jy@cn.fujitsu.com

Cc: stable@vger.kernel.org
Fixes: 93e31ffbf4 ("tracing: Add 'snapshot' event trigger command")
Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2020-04-21 09:04:59 +02:00

..

blktrace.c

blktrace: fix dereference after null check

2020-03-12 13:00:10 +01:00

bpf_trace.c

bpf: Fix deadlock with rq_lock in bpf_send_signal()

2020-04-17 10:49:57 +02:00

fgraph.c

ftrace: Look up the address of return_to_handler() using helpers

2019-09-18 12:24:47 +10:00

ftrace_internal.h

treewide: Rename rcu_dereference_raw_notrace() to _check()

2019-08-01 14:16:21 -07:00

ftrace.c

ftrace: fpid_next() should increase position index

2020-02-24 08:36:59 +01:00

Kconfig

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

2019-09-18 12:34:53 -07:00

Makefile

…

power-traces.c

…

preemptirq_delay_test.c

…

ring_buffer_benchmark.c

tracing: Use CONFIG_PREEMPTION

2019-07-31 19:03:35 +02:00

ring_buffer.c

tracing: Do not create directories if lockdown is in affect

2020-01-12 12:21:45 +01:00

rpm-traces.c

…

trace_benchmark.c

…

trace_benchmark.h

…

trace_branch.c

…

trace_clock.c

…

trace_dynevent.c

tracing: Add tracing_check_open_get_tr()

2019-10-12 20:44:07 -04:00

trace_dynevent.h

tracing/dynevent: Pass extra arguments to match operation

2019-08-31 12:19:38 -04:00

trace_entries.h

…

trace_event_perf.c

tracing: Fix race in perf_trace_buf initialization

2019-10-21 19:38:28 -04:00

trace_events_filter_test.h

…

trace_events_filter.c

tracing: Avoid memory leak in process_system_preds()

2020-01-09 10:20:00 +01:00

trace_events_hist.c

tracing: Fix number printing bug in print_synth_event()

2020-03-21 08:11:49 +01:00

trace_events_trigger.c

tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation

2020-04-21 09:04:59 +02:00

trace_events.c

tracing: Fix lock inversion in trace_event_enable_tgid_record()

2020-01-09 10:19:59 +01:00

trace_export.c

…

trace_functions_graph.c

fgraph: Remove redundant ftrace_graph_notrace_addr() test

2019-07-30 21:50:03 -04:00

trace_functions.c

…

trace_hwlat.c

tracing/hwlat: Don't ignore outer-loop duration when calculating max_latency

2019-10-12 20:49:33 -04:00

trace_irqsoff.c

…

trace_kdb.c

tracing: Silence GCC 9 array bounds warning

2019-05-25 23:04:30 -04:00

trace_kprobe_selftest.c

…

trace_kprobe_selftest.h

…

trace_kprobe.c

ftrace/kprobe: Show the maxactive number on kprobe_events

2020-04-17 10:50:21 +02:00

trace_mmiotrace.c

…

trace_nop.c

…

trace_output.c

tracing: Be more clever when dumping hex in __print_hex()

2019-09-17 11:21:28 -04:00

trace_output.h

…

trace_preemptirq.c

…

trace_printk.c

tracing: Add locked_down checks to the open calls of files created for tracefs

2019-10-12 20:48:06 -04:00

trace_probe_tmpl.h

tracing/probe: Support user-space dereference

2019-05-25 23:04:42 -04:00

trace_probe.c

tracing/kprobes: Have uname use __get_str() in print_fmt

2020-02-11 04:35:07 -08:00

trace_probe.h

tracing/uprobe: Fix to make trace_uprobe_filter alignment safe

2020-02-05 21:22:53 +00:00

trace_sched_switch.c

tracing: Fix sched switch start/stop refcount racy updates

2020-02-11 04:35:07 -08:00

trace_sched_wakeup.c

kernel/trace: Fix do not unregister tracepoints when register sched_migrate_task fail

2020-01-14 20:08:22 +01:00

trace_selftest_dynamic.c

…

trace_selftest.c

function_graph: Have selftest also emulate tr->reset() as it did with tr->init()

2019-04-21 19:46:56 -04:00

trace_seq.c

…

trace_stack.c

tracing: Have stack tracer compile when MCOUNT_INSN_SIZE is not defined

2020-01-14 20:08:22 +01:00

trace_stat.c

tracing: Fix very unlikely race of registering two stat tracers

2020-02-24 08:36:30 +01:00

trace_stat.h

…

trace_syscalls.c

…

trace_uprobe.c

tracing/uprobe: Fix to make trace_uprobe_filter alignment safe

2020-02-05 21:22:53 +00:00

trace.c

tracing: Disable trace_printk() on post poned tests

2020-03-05 16:43:43 +01:00

trace.h

ftrace: Protect ftrace_graph_hash with ftrace_sync

2020-02-11 04:35:28 -08:00

tracing_map.c

tracing: Have the histogram compare functions convert to u64 first

2020-01-09 10:20:00 +01:00

tracing_map.h

…