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authorLinus Torvalds <torvalds@linux-foundation.org>2013-05-28 09:39:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-28 09:39:04 -0700
commite3bf756eb988ff03ac57fda3934c440fe4db6a73 (patch)
tree53dbd9a0375dd8b190d326ef032661921c9f1975 /kernel
parent3c48dd49646f156158c1a96ec637b9f987f517fe (diff)
parent6721cb60022629ae76365551f05d9658b8d14c55 (diff)
Merge tag 'trace-fixes-v3.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt: "Two more fixes: The first one was reported by Mauro Carvalho Chehab, where if a poll() is done against a trace buffer for a CPU that has never been online, it will crash the kernel, as buffers are only created when a CPU comes on line, but the trace files are for all possible CPUs. This fix is to check if the buffer was allocated and if not return -EINVAL. That was the simple fix, the real fix is a bit more complex and not for a -rc release. We could have the files created when the CPUs come online. That would require some design changes. The second one was reported by Peter Zijlstra. If the kernel command line has ftrace=nop, it will lock up the system on boot up. This is because the new design for 3.10 has the nop tracer bootstrap the tracing subsystem. When ftrace=<trace> is defined, when a that tracer is registered, it starts the tracing, but uses the nop tracer to clear things out. What happened here was that ftrace=nop caused the registering of nop to start it and use nop before it was initialized. The only thing nop needs to have done to initialize it is to have the tracer point its current_tracer structure member to the nop tracer. Doing that before registering the nop tracer makes everything work." * tag 'trace-fixes-v3.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ring-buffer: Do not poll non allocated cpu buffers tracing: Fix crash when ftrace=nop on the kernel command line
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ring_buffer.c3
-rw-r--r--kernel/trace/trace.c9
2 files changed, 10 insertions, 2 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b59aea2c48c2..e444ff88f0a4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -620,6 +620,9 @@ int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
if (cpu == RING_BUFFER_ALL_CPUS)
work = &buffer->irq_work;
else {
+ if (!cpumask_test_cpu(cpu, buffer->cpumask))
+ return -EINVAL;
+
cpu_buffer = buffer->buffers[cpu];
work = &cpu_buffer->irq_work;
}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ae6fa2d1cdf7..4d79485b3237 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6216,10 +6216,15 @@ __init static int tracer_alloc_buffers(void)
trace_init_cmdlines();
- register_tracer(&nop_trace);
-
+ /*
+ * register_tracer() might reference current_trace, so it
+ * needs to be set before we register anything. This is
+ * just a bootstrap of current_trace anyway.
+ */
global_trace.current_trace = &nop_trace;
+ register_tracer(&nop_trace);
+
/* All seems OK, enable tracing */
tracing_disabled = 0;