2fd5a462eb
commit b40341fad6cc2daa195f8090fd3348f18fff640a upstream.
The first thing that the ftrace function callback helper functions should do
is to check for recursion. Peter Zijlstra found that when
"rcu_is_watching()" had its notrace removed, it caused perf function tracing
to crash. This is because the call of rcu_is_watching() is tested before
function recursion is checked and and if it is traced, it will cause an
infinite recursion loop.
rcu_is_watching() should still stay notrace, but to prevent this should
never had crashed in the first place. The recursion prevention must be the
first thing done in callback functions.
Link: https://lore.kernel.org/r/20200929112541.GM2628@hirez.programming.kicks-ass.net
Cc: stable@vger.kernel.org
Cc: Paul McKenney <paulmck@kernel.org>
Fixes:
|
||
|---|---|---|
| .. | ||
| blktrace.c | ||
| bpf_trace.c | ||
| ftrace.c | ||
| Kconfig | ||
| Makefile | ||
| power-traces.c | ||
| preemptirq_delay_test.c | ||
| ring_buffer.c | ||
| ring_buffer_benchmark.c | ||
| rpm-traces.c | ||
| trace.c | ||
| trace.h | ||
| trace_benchmark.c | ||
| trace_benchmark.h | ||
| trace_branch.c | ||
| trace_clock.c | ||
| trace_entries.h | ||
| trace_event_perf.c | ||
| trace_events.c | ||
| trace_events_filter.c | ||
| trace_events_filter_test.h | ||
| trace_events_hist.c | ||
| trace_events_trigger.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_output.c | ||
| trace_output.h | ||
| trace_preemptirq.c | ||
| trace_printk.c | ||
| trace_probe.c | ||
| trace_probe.h | ||
| 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_syscalls.c | ||
| trace_uprobe.c | ||
| tracing_map.c | ||
| tracing_map.h | ||