On Thu, Jun 28, 2018 at 11:21:42AM -0700, Joel Fernandes wrote:
From: "Joel Fernandes (Google)" joel@joelfernandes.org
This is a posting of v9 preempt/irq tracepoint clean up series rebased onto v4.18-rc2. No changes in the series, just a rebase + repost.
All patches have a Reviewed-by tags now from reviewers. This series has been well tested and is a simplification/refactoring of existing code, along with giving a speed-up for tracepoints using the rcu-idle API. With this our users will find it easier to use tools depending on existing preempt tracepoints since it simplifies the configuration for them.
Steve, all patches of this tracing series have been reviewed and/or acked and there haven't been additional changes for a couple of reposts. Are you Ok with it?
Thanks,
-Joel
Future enhancements/fixes I am developing for preempt-off tracer will depend on these patches, so I suggest prioritizing these well reviewed and tested patches for that reason as well.
Introduction to the series: The preempt/irq tracepoints exist but not everything in the kernel is using it whenever they need to be notified that a preempt disable/enable or an irq disable/enable has occurred. This makes things not work simultaneously (for example, only either lockdep or irqsoff trace-events can be used at a time).
This is particularly painful to deal with, since turning on lockdep breaks tracers that install probes on IRQ events, such as the BCC atomic critical section tracer [1]. This constraint also makes it impossible to use synthetic events to trace irqsoff sections with lockdep simulataneously turned on.
This series solves that, and also results in a nice clean up of relevant parts of the kernel. Several ifdefs are simpler, and the design is more unified and better. Also as a result of this, we also speeded performance all rcuidle tracepoints since their handling is simpler.
[1] https://github.com/iovisor/bcc/blob/master/tools/criticalstat_example.txt
v8->v9:
- Small style changes to tracepoint code (Mathieu)
- Minor style fix to use PTR_ERR_OR_ZERO (0-day bot)
- Minor fix to test_atomic_sections to use unsigned long.
- Added Namhyung's, Mathieu's Reviewed-by to some patches.
- Added Acks from Matsami
v7->v8:
- Refactored irqsoff tracer probe defines (Namhyung)
v6->v7:
Added a module to simulate an atomic section, a kselftest to load and and trigger it which verifies the preempt-tracer and this series.
Fixed a new warning after I rebased in early boot, this is because
early_boot_irqs_disabled was set too early, I moved it after the lockdep initialization.
added back the softirq fix since it appears it wasn't picked up.
Ran Ingo's locking API selftest suite which are passing with this series.
Mathieu suggested ifdef'ing the tracepoint_synchronize_unregister function incase tracepoints aren't enabled, did that.
Joel Fernandes (Google) (6): srcu: Add notrace variant of srcu_dereference trace/irqsoff: Split reset into separate functions tracepoint: Make rcuidle tracepoint callers use SRCU tracing: Centralize preemptirq tracepoints and unify their usage lib: Add module to simulate atomic sections for testing preemptoff tracers kselftests: Add tests for the preemptoff and irqsoff tracers
Paul McKenney (1): srcu: Add notrace variants of srcu_read_{lock,unlock}
include/linux/ftrace.h | 11 +- include/linux/irqflags.h | 11 +- include/linux/lockdep.h | 8 +- include/linux/preempt.h | 2 +- include/linux/srcu.h | 22 ++ include/linux/tracepoint.h | 49 +++- include/trace/events/preemptirq.h | 23 +- init/main.c | 5 +- kernel/locking/lockdep.c | 35 +-- kernel/sched/core.c | 2 +- kernel/trace/Kconfig | 22 +- kernel/trace/Makefile | 2 +- kernel/trace/trace_irqsoff.c | 253 ++++++------------ kernel/trace/trace_preemptirq.c | 71 +++++ kernel/tracepoint.c | 16 +- lib/Kconfig.debug | 8 + lib/Makefile | 1 + lib/test_atomic_sections.c | 77 ++++++ tools/testing/selftests/ftrace/config | 3 + .../test.d/preemptirq/irqsoff_tracer.tc | 73 +++++ 20 files changed, 453 insertions(+), 241 deletions(-) create mode 100644 kernel/trace/trace_preemptirq.c create mode 100644 lib/test_atomic_sections.c create mode 100644 tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc
-- 2.18.0.rc2.346.g013aa6912e-goog
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