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tracing/ftrace: Allow for instances to trigger their own stacktrace probes

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Have the stacktrace function trigger probe trigger stack traces within the
instance that they were added to in the set_ftrace_filter.

 ># cd /sys/kernel/debug/tracing
 ># mkdir instances/foo
 ># cd instances/foo
 ># echo schedule:stacktrace:1 > set_ftrace_filter
 ># cat trace
 # tracer: nop
 #
 # entries-in-buffer/entries-written: 1/1   #P:4
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
           <idle>-0     [001] .N.2   202.585010: <stack trace>
  =>
  => schedule
  => schedule_preempt_disabled
  => do_idle
  => cpu_startup_entry
  => start_secondary
  => verify_cpu

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware)
2017-04-20 11:59:18 -04:00
parent 2290f2c589
commit dcc19d2809
1 changed files with 14 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
kernel/trace/trace_functions.c
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@@ -375,12 +375,23 @@ ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
*/
#define STACK_SKIP 4
static __always_inline void trace_stack(struct trace_array *tr)
{
unsigned long flags;
int pc;
local_save_flags(flags);
pc = preempt_count();
__trace_stack(tr, flags, STACK_SKIP, pc);
}
static void
ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
struct trace_array *tr, struct ftrace_probe_ops *ops,
void *data)
{
trace_dump_stack(STACK_SKIP);
trace_stack(tr);
}
static void
@@ -398,7 +409,7 @@ ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
/* unlimited? */
if (!mapper) {
trace_dump_stack(STACK_SKIP);
trace_stack(tr);
return;
}
@@ -417,7 +428,7 @@ ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
new_count = old_count - 1;
new_count = cmpxchg(count, old_count, new_count);
if (new_count == old_count)
trace_dump_stack(STACK_SKIP);
trace_stack(tr);
if (!tracing_is_on())
return;