4.4-stable review patch. If anyone has any objections, please let me know.
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From: Changbin Du changbin.du@intel.com
commit 1fe4293f4b8de75824935f8d8e9a99c7fc6873da upstream.
The function_graph tracer does not show the interrupt return marker for the leaf entry. On leaf entries, we see an unbalanced interrupt marker (the interrupt was entered, but nevern left).
Before: 1) | SyS_write() { 1) | __fdget_pos() { 1) 0.061 us | __fget_light(); 1) 0.289 us | } 1) | vfs_write() { 1) 0.049 us | rw_verify_area(); 1) + 15.424 us | __vfs_write(); 1) ==========> | 1) 6.003 us | smp_apic_timer_interrupt(); 1) 0.055 us | __fsnotify_parent(); 1) 0.073 us | fsnotify(); 1) + 23.665 us | } 1) + 24.501 us | }
After: 0) | SyS_write() { 0) | __fdget_pos() { 0) 0.052 us | __fget_light(); 0) 0.328 us | } 0) | vfs_write() { 0) 0.057 us | rw_verify_area(); 0) | __vfs_write() { 0) ==========> | 0) 8.548 us | smp_apic_timer_interrupt(); 0) <========== | 0) + 36.507 us | } /* __vfs_write */ 0) 0.049 us | __fsnotify_parent(); 0) 0.066 us | fsnotify(); 0) + 50.064 us | } 0) + 50.952 us | }
Link: http://lkml.kernel.org/r/1517413729-20411-1-git-send-email-changbin.du@intel...
Cc: stable@vger.kernel.org Fixes: f8b755ac8e0cc ("tracing/function-graph-tracer: Output arrows signal on hardirq call/return") Signed-off-by: Changbin Du changbin.du@intel.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/trace_functions_graph.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -768,6 +768,7 @@ print_graph_entry_leaf(struct trace_iter struct ftrace_graph_ret *graph_ret; struct ftrace_graph_ent *call; unsigned long long duration; + int cpu = iter->cpu; int i;
graph_ret = &ret_entry->ret; @@ -776,7 +777,6 @@ print_graph_entry_leaf(struct trace_iter
if (data) { struct fgraph_cpu_data *cpu_data; - int cpu = iter->cpu;
cpu_data = per_cpu_ptr(data->cpu_data, cpu);
@@ -806,6 +806,9 @@ print_graph_entry_leaf(struct trace_iter
trace_seq_printf(s, "%ps();\n", (void *)call->func);
+ print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET, + cpu, iter->ent->pid, flags); + return trace_handle_return(s); }