user/sven/linux.git/kernel/trace/trace_selftest.c, branch v3.9.8

tracing: Fix ftrace_dump()

2013-05-11T14:18:36Z

commit 7fe70b579c9e3daba71635e31b6189394e7b79d3 upstream. ftrace_dump() had a lot of issues. What ftrace_dump() does, is when ftrace_dump_on_oops is set (via a kernel parameter or sysctl), it will dump out the ftrace buffers to the console when either a oops, panic, or a sysrq-z occurs. This was written a long time ago when ftrace was fragile to recursion. But it wasn't written well even for that. There's a possible deadlock that can occur if a ftrace_dump() is happening and an NMI triggers another dump. This is because it grabs a lock before checking if the dump ran. It also totally disables ftrace, and tracing for no good reasons. As the ring_buffer now checks if it is read via a oops or NMI, where there's a chance that the buffer gets corrupted, it will disable itself. No need to have ftrace_dump() do the same. ftrace_dump() is now cleaned up where it uses an atomic counter to make sure only one dump happens at a time. A simple atomic_inc_return() is enough that is needed for both other CPUs and NMIs. No need for a spinlock, as if one CPU is running the dump, no other CPU needs to do it too. The tracing_on variable is turned off and not turned on. The original code did this, but it wasn't pretty. By just disabling this variable we get the result of not seeing traces that happen between crashes. For sysrq-z, it doesn't get turned on, but the user can always write a '1' to the tracing_on file. If they are using sysrq-z, then they should know about tracing_on. The new code is much easier to read and less error prone. No more deadlock possibility when an NMI triggers here. Reported-by: zhangwei(Jovi) Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Frederic Weisbecker Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ftrace: Fix function tracing recursion self test

2013-01-23T04:37:58Z

The function tracing recursion self test should not crash the machine if the resursion test fails. If it detects that the function tracing is recursing when it should not be, then bail, don't go into an infinite recursive loop. Signed-off-by: Steven Rostedt

tracing: Fix selftest function recursion accounting

2013-01-23T04:35:11Z

The test that checks function recursion does things differently if the arch does not support all ftrace features. But that really doesn't make a difference with how the test runs, and either way the count variable should be 2 at the end. Currently the test wrongly fails for archs that don't support all the ftrace features. Signed-off-by: Steven Rostedt

ftrace: Move ARCH_SUPPORTS_FTRACE_SAVE_REGS in Kconfig

2013-01-21T18:22:35Z

Move SAVE_REGS support flag into Kconfig and rename it to CONFIG_DYNAMIC_FTRACE_WITH_REGS. This also introduces CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS which indicates the architecture depending part of ftrace has a code that saves full registers. On the other hand, CONFIG_DYNAMIC_FTRACE_WITH_REGS indicates the code is enabled. Link: http://lkml.kernel.org/r/20120928081516.3560.72534.stgit@ltc138.sdl.hitachi.co.jp Cc: Ingo Molnar Cc: Ananth N Mavinakayanahalli Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Frederic Weisbecker Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt

tracing: Use irq_work for wake ups and remove _nowake_() functions

2012-11-02T14:21:52Z

Have the ring buffer commit function use the irq_work infrastructure to wake up any waiters waiting on the ring buffer for new data. The irq_work was created for such a purpose, where doing the actual wake up at the time of adding data is too dangerous, as an event or function trace may be in the midst of the work queue locks and cause deadlocks. The irq_work will either delay the action to the next timer interrupt, or trigger an IPI to itself forcing an interrupt to do the work (in a safe location). With irq_work, all ring buffer commits can safely do wakeups, removing the need for the ring buffer commit "nowake" variants, which were used by events and function tracing. All commits can now safely use the normal commit, and the "nowake" variants can be removed. Cc: Peter Zijlstra Signed-off-by: Steven Rostedt

tracing: Make tracing_enabled be equal to tracing_on

2012-11-02T14:21:50Z

The tracing_enabled file has been deprecated as it never was able to serve its purpose well. The tracing_on file has taken over. Instead of having code to keep tracing_enabled, have the tracing_enabled file just set tracing_on, and remove the tracing_enabled variable. This allows us to remove the tracing_enabled file. The reason that the remove is in a different change set and not removed here is in case we find some lonely userspace tool that requires the file to exist. Then the removal patch will get reverted, but this one will not. Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Steven Rostedt

tracing: Fix wakeup_rt self test on virtual machines

2012-08-07T13:40:51Z

The warkeup_rt self test used msleep() calls to wait for real time tasks to wake up and run. On bare-metal hardware, this was enough as the scheduler should let the RT task run way before the non-RT task wakes up from the msleep(). If it did not, then that would mean the scheduler was broken. But when dealing with virtual machines, this is a different story. If the RT task wakes up on a VCPU, it's up to the host to decide when that task gets to schedule, which can be far behind the time that the non-RT task wakes up. In this case, the test would fail incorrectly. As we are not testing the scheduler, but instead the wake up tracing, we can use completions to wait and not depend on scheduler timings to see if events happen on time. Link: http://lkml.kernel.org/r/1343663105.3847.7.camel@fedora Reported-by: Fengguang Wu Tested-by: Fengguang Wu Signed-off-by: Steven Rostedt

ftrace: Add selftest to test function save-regs support

2012-07-31T14:29:54Z

Add selftests to test the save-regs functionality of ftrace. If the arch supports saving regs, then it will make sure that regs is at least not NULL in the callback. If the arch does not support saving regs, it makes sure that the registering of the ftrace_ops that requests saving regs fails. It then tests the registering of the ftrace_ops succeeds if the 'IF_SUPPORTED' flag is set. Then it makes sure that the regs passed to the function is NULL. Signed-off-by: Steven Rostedt

ftrace: Add selftest to test function trace recursion protection

2012-07-31T14:29:54Z

Add selftests to test the function tracing recursion protection actually does work. It also tests if a ftrace_ops states it will perform its own protection. Although, even if the ftrace_ops states it will protect itself, the ftrace infrastructure may still provide protection if the arch does not support all features or another ftrace_ops is registered. Signed-off-by: Steven Rostedt

ftrace: Add default recursion protection for function tracing

2012-07-31T14:29:52Z

As more users of the function tracer utility are being added, they do not always add the necessary recursion protection. To protect from function recursion due to tracing, if the callback ftrace_ops does not specifically specify that it protects against recursion (by setting the FTRACE_OPS_FL_RECURSION_SAFE flag), the list operation will be called by the mcount trampoline which adds recursion protection. If the flag is set, then the function will be called directly with no extra protection. Note, the list operation is called if more than one function callback is registered, or if the arch does not support all of the function tracer features. Signed-off-by: Steven Rostedt

user/sven/linux.git/kernel/trace/trace_selftest.c, branch v3.9.8

tracing: Fix ftrace_dump()

ftrace: Fix function tracing recursion self test

tracing: Fix selftest function recursion accounting

ftrace: Move ARCH_SUPPORTS_FTRACE_SAVE_REGS in Kconfig

tracing: Use irq_work for wake ups and remove *_nowake_*() functions

tracing: Make tracing_enabled be equal to tracing_on

tracing: Fix wakeup_rt self test on virtual machines

ftrace: Add selftest to test function save-regs support

ftrace: Add selftest to test function trace recursion protection

ftrace: Add default recursion protection for function tracing

tracing: Use irq_work for wake ups and remove _nowake_() functions