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7249921d94
If in perf_trace_event_init(), the perf_trace_event_open() fails, then it
will call perf_trace_event_unreg() which will not only unregister the perf
trace event, but will also call the put() function of the tp_event.
The problem here is that the trace_event_try_get_ref() is called by the
caller of perf_trace_event_init() and if perf_trace_event_init() returns a
failure, it will then call trace_event_put(). But since the
perf_trace_event_unreg() already called the trace_event_put() function, it
triggers a WARN_ON().
WARNING: CPU: 1 PID: 30309 at kernel/trace/trace_dynevent.c:46 trace_event_dyn_put_ref+0x15/0x20
If perf_trace_event_reg() does not call the trace_event_try_get_ref() then
the perf_trace_event_unreg() should not be calling trace_event_put(). This
breaks symmetry and causes bugs like these.
Pull out the trace_event_put() from perf_trace_event_unreg() and call it
in the locations that perf_trace_event_unreg() is called. This not only
fixes this bug, but also brings back the proper symmetry of the reg/unreg
vs get/put logic.
Link: https://lore.kernel.org/all/cover.1660347763.git.kjlx@templeofstupid.com/
Link: https://lkml.kernel.org/r/20220816192817.43d5e17f@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes:
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.. | ||
rv | ||
blktrace.c | ||
bpf_trace.c | ||
bpf_trace.h | ||
error_report-traces.c | ||
fgraph.c | ||
fprobe.c | ||
ftrace.c | ||
ftrace_internal.h | ||
Kconfig | ||
kprobe_event_gen_test.c | ||
Makefile | ||
pid_list.c | ||
pid_list.h | ||
power-traces.c | ||
preemptirq_delay_test.c | ||
rethook.c | ||
ring_buffer.c | ||
ring_buffer_benchmark.c | ||
rpm-traces.c | ||
synth_event_gen_test.c | ||
trace.c | ||
trace.h | ||
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_eprobe.c | ||
trace_event_perf.c | ||
trace_events.c | ||
trace_events_filter.c | ||
trace_events_filter_test.h | ||
trace_events_hist.c | ||
trace_events_inject.c | ||
trace_events_synth.c | ||
trace_events_trigger.c | ||
trace_events_user.c | ||
trace_export.c | ||
trace_functions.c | ||
trace_functions_graph.c | ||
trace_hwlat.c | ||
trace_irqsoff.c | ||
trace_kdb.c | ||
trace_kprobe.c | ||
trace_kprobe_selftest.c | ||
trace_kprobe_selftest.h | ||
trace_mmiotrace.c | ||
trace_nop.c | ||
trace_osnoise.c | ||
trace_output.c | ||
trace_output.h | ||
trace_preemptirq.c | ||
trace_printk.c | ||
trace_probe.c | ||
trace_probe.h | ||
trace_probe_tmpl.h | ||
trace_recursion_record.c | ||
trace_sched_switch.c | ||
trace_sched_wakeup.c | ||
trace_selftest.c | ||
trace_selftest_dynamic.c | ||
trace_seq.c | ||
trace_stack.c | ||
trace_stat.c | ||
trace_stat.h | ||
trace_synth.h | ||
trace_syscalls.c | ||
trace_uprobe.c | ||
tracing_map.c | ||
tracing_map.h |