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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-05-12 19:15:45 +0200 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-05-19 05:57:56 +0200 |
| commit | a33d7d94eed92b23fbbc7b0de06a41b2bbaa49e3 (patch) | |
| tree | 4663e28c01cc8cffb139af6afeb950532d1e4adc | |
| parent | kprobes: Document how optimized kprobes are removed from module unload (diff) | |
| download | linux-a33d7d94eed92b23fbbc7b0de06a41b2bbaa49e3.tar.xz linux-a33d7d94eed92b23fbbc7b0de06a41b2bbaa49e3.zip | |
tracing: Make sure RCU is watching before calling a stack trace
As stack tracing now requires "rcu watching", force RCU to be watching when
recording a stack trace.
Link: http://lkml.kernel.org/r/20170512172449.879684501@goodmis.org
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/trace.c | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index fcc9a2d774c3..1122f151466f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2568,7 +2568,36 @@ static inline void ftrace_trace_stack(struct trace_array *tr, void __trace_stack(struct trace_array *tr, unsigned long flags, int skip, int pc) { - __ftrace_trace_stack(tr->trace_buffer.buffer, flags, skip, pc, NULL); + struct ring_buffer *buffer = tr->trace_buffer.buffer; + + if (rcu_is_watching()) { + __ftrace_trace_stack(buffer, flags, skip, pc, NULL); + return; + } + + /* + * When an NMI triggers, RCU is enabled via rcu_nmi_enter(), + * but if the above rcu_is_watching() failed, then the NMI + * triggered someplace critical, and rcu_irq_enter() should + * not be called from NMI. + */ + if (unlikely(in_nmi())) + return; + + /* + * It is possible that a function is being traced in a + * location that RCU is not watching. A call to + * rcu_irq_enter() will make sure that it is, but there's + * a few internal rcu functions that could be traced + * where that wont work either. In those cases, we just + * do nothing. + */ + if (unlikely(rcu_irq_enter_disabled())) + return; + + rcu_irq_enter_irqson(); + __ftrace_trace_stack(buffer, flags, skip, pc, NULL); + rcu_irq_exit_irqson(); } /** |