linux/kernel/trace/trace_functions.c, branch v3.14-rc5

tracing: Add ref_data to function and fgraph tracer structs

2013-07-19T01:31:31Z

The selftest for function and function graph tracers are defined as __init, as they are only executed at boot up. The "tracer" structs that are associated to those tracers are not setup as __init as they are used after boot. To stop mismatch warnings, those structures need to be annotated with __ref_data. Currently, the tracer structures are defined to __read_mostly, as they do not really change. But in the future they should be converted to consts, but that will take a little work because they have a "next" pointer that gets updated when they are registered. That will have to wait till the next major release. Link: http://lkml.kernel.org/r/1373596735.17876.84.camel@gandalf.local.home Reported-by: kbuild test robot Reported-by: Chen Gang Signed-off-by: Steven Rostedt

tracing: Add function probe to trigger a ftrace dump of current CPU trace

2013-06-11T22:38:48Z

Add the "cpudump" command to have the current CPU ftrace buffer dumped to console if a function is hit. This is useful when debugging a tripple fault, where you have an idea of a function that is called just before the tripple fault occurs, and can tell ftrace to dump its content out to the console before it continues. This differs from the "dump" command as it only dumps the content of the ring buffer for the currently executing CPU, and does not show the contents of the other CPUs. Format is: :cpudump echo 'bad_address:cpudump' > /debug/tracing/set_ftrace_filter To remove this: echo '!bad_address:cpudump' > /debug/tracing/set_ftrace_filter Signed-off-by: Steven Rostedt

tracing: Add function probe to trigger a ftrace dump to console

2013-06-11T22:38:46Z

Add the "dump" command to have the ftrace buffer dumped to console if a function is hit. This is useful when debugging a tripple fault, where you have an idea of a function that is called just before the tripple fault occurs, and can tell ftrace to dump its content out to the console before it continues. Format is: :dump echo 'bad_address:dump' > /debug/tracing/set_ftrace_filter To remove this: echo '!bad_address:dump' > /debug/tracing/set_ftrace_filter Requested-by: Luis Claudio R. Goncalves Signed-off-by: Steven Rostedt

tracing: Add function probe to trigger stack traces

2013-03-15T04:36:05Z

Add a function probe that will cause a stack trace to be traced in the ring buffer when the given function(s) are called. format is: :stacktrace[:] echo 'schedule:stacktrace' > /debug/tracing/set_ftrace_filter cat /debug/tracing/trace_pipe kworker/2:0-4329 [002] ...2 2933.558007: => kthread => ret_from_fork -0 [000] .N.2 2933.558019: => rest_init => start_kernel => x86_64_start_reservations => x86_64_start_kernel kworker/2:0-4329 [002] ...2 2933.558109: => kthread => ret_from_fork [...] This can be set to only trace a specific amount of times: echo 'schedule:stacktrace:3' > /debug/tracing/set_ftrace_filter cat /debug/tracing/trace_pipe <...>-58 [003] ...2 841.801694: => kthread => ret_from_fork -0 [001] .N.2 841.801697: => start_secondary <...>-2059 [001] ...2 841.801736: => wait_for_common => wait_for_completion => flush_work => tty_flush_to_ldisc => input_available_p => n_tty_poll => tty_poll => do_select => core_sys_select => sys_select => system_call_fastpath To remove these: echo '!schedule:stacktrace' > /debug/tracing/set_ftrace_filter echo '!schedule:stacktrace:0' > /debug/tracing/set_ftrace_filter Signed-off-by: Steven Rostedt

ftrace: Separate unlimited probes from count limited probes

2013-03-15T04:35:59Z

The function tracing probes that trigger traceon or traceoff can be set to unlimited, or given a count of # of times to execute. By separating these two types of probes, we can then use the dynamic ftrace function filtering directly, and remove the brute force "check if this function called is my probe" routines in ftrace. Signed-off-by: Steven Rostedt

tracing: Consolidate ftrace_trace_onoff_unreg() into callback

2013-03-15T04:35:58Z

The only thing ftrace_trace_onoff_unreg() does is to do a strcmp() against the cmd parameter to determine what op to unregister. But this compare is also done after the location that this function is called (and returns). By moving the check for '!' to unregister after the strcmp(), the callback function itself can just do the unregister and we can get rid of the helper function. Signed-off-by: Steven Rostedt

tracing: Consolidate updating of count for traceon/off

2013-03-15T04:35:58Z

Remove some duplicate code and replace it with a helper function. This makes the code a it cleaner. Signed-off-by: Steven Rostedt

tracing: Consolidate max_tr into main trace_array structure

2013-03-15T04:35:40Z

Currently, the way the latency tracers and snapshot feature works is to have a separate trace_array called "max_tr" that holds the snapshot buffer. For latency tracers, this snapshot buffer is used to swap the running buffer with this buffer to save the current max latency. The only items needed for the max_tr is really just a copy of the buffer itself, the per_cpu data pointers, the time_start timestamp that states when the max latency was triggered, and the cpu that the max latency was triggered on. All other fields in trace_array are unused by the max_tr, making the max_tr mostly bloat. This change removes the max_tr completely, and adds a new structure called trace_buffer, that holds the buffer pointer, the per_cpu data pointers, the time_start timestamp, and the cpu where the latency occurred. The trace_array, now has two trace_buffers, one for the normal trace and one for the max trace or snapshot. By doing this, not only do we remove the bloat from the max_trace but the instances of traces can now use their own snapshot feature and not have just the top level global_trace have the snapshot feature and latency tracers for itself. Signed-off-by: Steven Rostedt

tracing: Replace the static global per_cpu arrays with allocated per_cpu

2013-03-15T04:34:43Z

The global and max-tr currently use static per_cpu arrays for the CPU data descriptors. But in order to get new allocated trace_arrays, they need to be allocated per_cpu arrays. Instead of using the static arrays, switch the global and max-tr to use allocated data. Signed-off-by: Steven Rostedt

tracing: Fix unsigned int compare of zero in recursion check

2013-01-24T12:52:34Z

Dan's smatch found a compare bug with the result of the trace_test_and_set_recursion() and comparing to less than zero. If the function fails, it returns -1, but was saved in an unsigned int, which will never be less than zero and will ignore the result of the test if a recursion did happen. Luckily this is the last of the recursion tests, as the infrastructure of ftrace would catch recursions before it got here, except for some few exceptions. Reported-by: Dan Carpenter Signed-off-by: Steven Rostedt