Commit ac1d52d0 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

tracing/ftrace: fix double calls to tracing_start()



Impact: fix a warning during preemptirqsoff selftests

When the preemptirqsoff selftest fails, we see the following
warning:

[    6.050000] Testing tracer preemptirqsoff: .. no entries found ..
------------[ cut here ]------------
[    6.060000] WARNING: at kernel/trace/trace.c:688 tracing_start+0x67/0xd3()
[    6.060000] Modules linked in:
[    6.060000] Pid: 1, comm: swapper Tainted: G
[    6.060000] Call Trace:
[    6.060000]  [<ffffffff802460ff>] warn_slowpath+0xb1/0x100
[    6.060000]  [<ffffffff802a8f5b>] ? trace_preempt_on+0x35/0x4b
[    6.060000]  [<ffffffff802a37fb>] ? tracing_start+0x31/0xd3
[    6.060000]  [<ffffffff802a37fb>] ? tracing_start+0x31/0xd3
[    6.060000]  [<ffffffff80271e0b>] ? __lock_acquired+0xe6/0x1f2
[    6.060000]  [<ffffffff802a37fb>] ? tracing_start+0x31/0xd3
[    6.060000]  [<ffffffff802a3831>] tracing_start+0x67/0xd3
[    6.060000]  [<ffffffff802a8ace>] ? irqsoff_tracer_reset+0x2d/0x57
[    6.060000]  [<ffffffff802a4d1c>] trace_selftest_startup_preemptirqsoff+0x1c8/0x1f1
[    6.060000]  [<ffffffff802a4798>] register_tracer+0x12f/0x241
[    6.060000]  [<ffffffff810250d0>] ? init_irqsoff_tracer+0x0/0x53
[    6.060000]  [<ffffffff8102510b>] init_irqsoff_tracer+0x3b/0x53

This is because in fail case, the preemptirqsoff tracer selftest calls twice
the tracing_start() function:

int
trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
{
        if (!ret && !count) {
                printk(KERN_CONT ".. no entries found ..");
                ret = -1;
                tracing_start(); <-----
                goto out;
        }
        [...]
out:
        trace->reset(tr);
        tracing_start(); <------
        tracing_max_latency = save_max;

        return ret;
}

Since it is well handled in the out path, we don't need the conditional one.
Reported-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237159961-7447-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 59f586db
......@@ -414,7 +414,7 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
ret = tracer_init(trace, tr);
if (ret) {
warn_failed_init_tracer(trace, ret);
goto out;
goto out_no_start;
}
/* reset the max latency */
......@@ -432,21 +432,16 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(tr, NULL);
if (ret) {
tracing_start();
if (ret)
goto out;
}
ret = trace_test_buffer(&max_tr, &count);
if (ret) {
tracing_start();
if (ret)
goto out;
}
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
tracing_start();
goto out;
}
......@@ -475,9 +470,10 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *
goto out;
}
out:
trace->reset(tr);
out:
tracing_start();
out_no_start:
trace->reset(tr);
tracing_max_latency = save_max;
return ret;
......
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