diff options
Diffstat (limited to 'kernel/trace/trace_functions_graph.c')
| -rw-r--r-- | kernel/trace/trace_functions_graph.c | 62 |
1 files changed, 46 insertions, 16 deletions
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index deff1120026..f0a0c982cde 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -15,6 +15,33 @@ #include "trace.h" #include "trace_output.h" +static bool kill_ftrace_graph; + +/** + * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called + * + * ftrace_graph_stop() is called when a severe error is detected in + * the function graph tracing. This function is called by the critical + * paths of function graph to keep those paths from doing any more harm. + */ +bool ftrace_graph_is_dead(void) +{ + return kill_ftrace_graph; +} + +/** + * ftrace_graph_stop - set to permanently disable function graph tracincg + * + * In case of an error int function graph tracing, this is called + * to try to keep function graph tracing from causing any more harm. + * Usually this is pretty severe and this is called to try to at least + * get a warning out to the user. + */ +void ftrace_graph_stop(void) +{ + kill_ftrace_graph = true; +} + /* When set, irq functions will be ignored */ static int ftrace_graph_skip_irqs; @@ -38,15 +65,6 @@ struct fgraph_data { #define TRACE_GRAPH_INDENT 2 -/* Flag options */ -#define TRACE_GRAPH_PRINT_OVERRUN 0x1 -#define TRACE_GRAPH_PRINT_CPU 0x2 -#define TRACE_GRAPH_PRINT_OVERHEAD 0x4 -#define TRACE_GRAPH_PRINT_PROC 0x8 -#define TRACE_GRAPH_PRINT_DURATION 0x10 -#define TRACE_GRAPH_PRINT_ABS_TIME 0x20 -#define TRACE_GRAPH_PRINT_IRQS 0x40 - static unsigned int max_depth; static struct tracer_opt trace_opts[] = { @@ -64,11 +82,13 @@ static struct tracer_opt trace_opts[] = { { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) }, /* Display interrupts */ { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) }, + /* Display function name after trailing } */ + { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) }, { } /* Empty entry */ }; static struct tracer_flags tracer_flags = { - /* Don't display overruns and proc by default */ + /* Don't display overruns, proc, or tail by default */ .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD | TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS, .opts = trace_opts @@ -99,6 +119,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, unsigned long long calltime; int index; + if (unlikely(ftrace_graph_is_dead())) + return -EBUSY; + if (!current->ret_stack) return -EBUSY; @@ -330,7 +353,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) return ret; } -int trace_graph_thresh_entry(struct ftrace_graph_ent *trace) +static int trace_graph_thresh_entry(struct ftrace_graph_ent *trace) { if (tracing_thresh) return 1; @@ -419,7 +442,7 @@ void set_graph_array(struct trace_array *tr) smp_mb(); } -void trace_graph_thresh_return(struct ftrace_graph_ret *trace) +static void trace_graph_thresh_return(struct ftrace_graph_ret *trace) { if (tracing_thresh && (trace->rettime - trace->calltime < tracing_thresh)) @@ -452,6 +475,12 @@ static void graph_trace_reset(struct trace_array *tr) unregister_ftrace_graph(); } +static int graph_trace_update_thresh(struct trace_array *tr) +{ + graph_trace_reset(tr); + return graph_trace_init(tr); +} + static int max_bytes_for_cpu; static enum print_line_t @@ -1176,9 +1205,10 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s, * If the return function does not have a matching entry, * then the entry was lost. Instead of just printing * the '}' and letting the user guess what function this - * belongs to, write out the function name. + * belongs to, write out the function name. Always do + * that if the funcgraph-tail option is enabled. */ - if (func_match) { + if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL)) { ret = trace_seq_puts(s, "}\n"); if (!ret) return TRACE_TYPE_PARTIAL_LINE; @@ -1405,7 +1435,7 @@ static void __print_graph_headers_flags(struct seq_file *s, u32 flags) seq_printf(s, " | | | |\n"); } -void print_graph_headers(struct seq_file *s) +static void print_graph_headers(struct seq_file *s) { print_graph_headers_flags(s, tracer_flags.val); } @@ -1501,11 +1531,11 @@ static struct trace_event graph_trace_ret_event = { static struct tracer graph_trace __tracer_data = { .name = "function_graph", + .update_thresh = graph_trace_update_thresh, .open = graph_trace_open, .pipe_open = graph_trace_open, .close = graph_trace_close, .pipe_close = graph_trace_close, - .wait_pipe = poll_wait_pipe, .init = graph_trace_init, .reset = graph_trace_reset, .print_line = print_graph_function, |