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alistair23-linux/kernel/trace
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
..
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2019-09-18 12:34:53 -07:00
Makefile
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.c ftrace: fpid_next() should increase position index 2020-02-24 08:36:59 +01:00
ftrace_internal.h
power-traces.c
preemptirq_delay_test.c
ring_buffer.c tracing: Do not create directories if lockdown is in affect 2020-01-12 12:21:45 +01:00
ring_buffer_benchmark.c
rpm-traces.c
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
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.c tracing: Fix lock inversion in trace_event_enable_tgid_record() 2020-01-09 10:19:59 +01:00
trace_events_filter.c tracing: Avoid memory leak in process_system_preds() 2020-01-09 10:20:00 +01:00
trace_events_filter_test.h
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_export.c
trace_functions.c
trace_functions_graph.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
trace_kprobe.c ftrace/kprobe: Show the maxactive number on kprobe_events 2020-04-17 10:50:21 +02:00
trace_kprobe_selftest.c
trace_kprobe_selftest.h
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.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_probe_tmpl.h
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.c
trace_selftest_dynamic.c
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
tracing_map.c tracing: Have the histogram compare functions convert to u64 first 2020-01-09 10:20:00 +01:00
tracing_map.h