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-rw-r--r--kernel/trace/trace.c62
-rw-r--r--kernel/trace/trace_selftest.c9
2 files changed, 31 insertions, 40 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7713d1b33da9..3f28192b420b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5168,36 +5168,32 @@ void trace_init_global_iter(struct trace_iterator *iter)
iter->cpu_file = TRACE_PIPE_ALL_CPU;
}
-static void
-__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
+void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
{
- static arch_spinlock_t ftrace_dump_lock =
- (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
+ static atomic_t dump_running;
unsigned int old_userobj;
- static int dump_ran;
unsigned long flags;
int cnt = 0, cpu;
- /* only one dump */
- local_irq_save(flags);
- arch_spin_lock(&ftrace_dump_lock);
- if (dump_ran)
- goto out;
-
- dump_ran = 1;
+ /* Only allow one dump user at a time. */
+ if (atomic_inc_return(&dump_running) != 1) {
+ atomic_dec(&dump_running);
+ return;
+ }
+ /*
+ * Always turn off tracing when we dump.
+ * We don't need to show trace output of what happens
+ * between multiple crashes.
+ *
+ * If the user does a sysrq-z, then they can re-enable
+ * tracing with echo 1 > tracing_on.
+ */
tracing_off();
- /* Did function tracer already get disabled? */
- if (ftrace_is_dead()) {
- printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
- printk("# MAY BE MISSING FUNCTION EVENTS\n");
- }
-
- if (disable_tracing)
- ftrace_kill();
+ local_irq_save(flags);
/* Simulate the iterator */
trace_init_global_iter(&iter);
@@ -5227,6 +5223,12 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
printk(KERN_TRACE "Dumping ftrace buffer:\n");
+ /* Did function tracer already get disabled? */
+ if (ftrace_is_dead()) {
+ printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
+ printk("# MAY BE MISSING FUNCTION EVENTS\n");
+ }
+
/*
* We need to stop all tracing on all CPUS to read the
* the next buffer. This is a bit expensive, but is
@@ -5266,26 +5268,14 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
printk(KERN_TRACE "---------------------------------\n");
out_enable:
- /* Re-enable tracing if requested */
- if (!disable_tracing) {
- trace_flags |= old_userobj;
+ trace_flags |= old_userobj;
- for_each_tracing_cpu(cpu) {
- atomic_dec(&iter.tr->data[cpu]->disabled);
- }
- tracing_on();
+ for_each_tracing_cpu(cpu) {
+ atomic_dec(&iter.tr->data[cpu]->disabled);
}
-
- out:
- arch_spin_unlock(&ftrace_dump_lock);
+ atomic_dec(&dump_running);
local_irq_restore(flags);
}
-
-/* By default: disable tracing after the dump */
-void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
-{
- __ftrace_dump(true, oops_dump_mode);
-}
EXPORT_SYMBOL_GPL(ftrace_dump);
__init static int tracer_alloc_buffers(void)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 51c819c12c29..eedc2978a884 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -703,8 +703,6 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
/* Maximum number of functions to trace before diagnosing a hang */
#define GRAPH_MAX_FUNC_TEST 100000000
-static void
-__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode);
static unsigned int graph_hang_thresh;
/* Wrap the real function entry probe to avoid possible hanging */
@@ -714,8 +712,11 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace)
if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
ftrace_graph_stop();
printk(KERN_WARNING "BUG: Function graph tracer hang!\n");
- if (ftrace_dump_on_oops)
- __ftrace_dump(false, DUMP_ALL);
+ if (ftrace_dump_on_oops) {
+ ftrace_dump(DUMP_ALL);
+ /* ftrace_dump() disables tracing */
+ tracing_on();
+ }
return 0;
}