Xiao Yang 0bbe7f7199 tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation ... 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>		2020-04-14 22:02:10 -04:00
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blktrace.c
bpf_trace.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next	2020-03-30 19:52:37 -07:00
fgraph.c
ftrace_internal.h
ftrace.c	New tracing features:	2020-04-05 10:36:18 -07:00
Kconfig
kprobe_event_gen_test.c
Makefile
power-traces.c
preemptirq_delay_test.c
ring_buffer_benchmark.c
ring_buffer.c	ring-buffer/tracing: Have iterator acknowledge dropped events	2020-03-27 16:39:01 -04:00
rpm-traces.c
synth_event_gen_test.c
trace_benchmark.c
trace_benchmark.h
trace_boot.c
trace_branch.c
trace_clock.c
trace_dynevent.c
trace_dynevent.h
trace_entries.h
trace_event_perf.c
trace_events_filter_test.h
trace_events_filter.c
trace_events_hist.c
trace_events_inject.c
trace_events_trigger.c	tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation	2020-04-14 22:02:10 -04:00
trace_events.c	tracing: Create set_event_notrace_pid to not trace tasks	2020-03-27 16:39:02 -04:00
trace_export.c
trace_functions_graph.c	ring-buffer: Rename ring_buffer_read() to read_buffer_iter_advance()	2020-03-19 19:11:19 -04:00
trace_functions.c
trace_hwlat.c
trace_irqsoff.c
trace_kdb.c
trace_kprobe_selftest.c
trace_kprobe_selftest.h
trace_kprobe.c	ftrace/kprobe: Show the maxactive number on kprobe_events	2020-03-27 16:39:02 -04:00
trace_mmiotrace.c
trace_nop.c
trace_output.c	tracing: Save off entry when peeking at next entry	2020-03-19 17:48:36 -04:00
trace_output.h
trace_preemptirq.c
trace_printk.c
trace_probe_tmpl.h
trace_probe.c
trace_probe.h
trace_sched_switch.c
trace_sched_wakeup.c
trace_selftest_dynamic.c
trace_selftest.c
trace_seq.c
trace_stack.c
trace_stat.c
trace_stat.h
trace_syscalls.c
trace_uprobe.c
trace.c	tracing: Do not allocate buffer in trace_find_next_entry() in atomic	2020-04-03 11:30:50 -04:00
trace.h	tracing: Create set_event_notrace_pid to not trace tasks	2020-03-27 16:39:02 -04:00
tracing_map.c
tracing_map.h