• Joel Fernandes (Google)'s avatar
    tracing: Centralize preemptirq tracepoints and unify their usage · c3bc8fd6
    Joel Fernandes (Google) authored
    This patch detaches the preemptirq tracepoints from the tracers and
    keeps it separate.
    
    Advantages:
    * Lockdep and irqsoff event can now run in parallel since they no longer
    have their own calls.
    
    * This unifies the usecase of adding hooks to an irqsoff and irqson
    event, and a preemptoff and preempton event.
      3 users of the events exist:
      - Lockdep
      - irqsoff and preemptoff tracers
      - irqs and preempt trace events
    
    The unification cleans up several ifdefs and makes the code in preempt
    tracer and irqsoff tracers simpler. It gets rid of all the horrific
    ifdeferry around PROVE_LOCKING and makes configuration of the different
    users of the tracepoints more easy and understandable. It also gets rid
    of the time_* function calls from the lockdep hooks used to call into
    the preemptirq tracer which is not needed anymore. The negative delta in
    lines of code in this patch is quite large too.
    
    In the patch we introduce a new CONFIG option PREEMPTIRQ_TRACEPOINTS
    as a single point for registering probes onto the tracepoints. With
    this,
    the web of config options for preempt/irq toggle tracepoints and its
    users becomes:
    
     PREEMPT_TRACER   PREEMPTIRQ_EVENTS  IRQSOFF_TRACER PROVE_LOCKING
           |                 |     \         |           |
           \    (selects)    /      \        \ (selects) /
          TRACE_PREEMPT_TOGGLE       ----> TRACE_IRQFLAGS
                          \                  /
                           \ (depends on)   /
                         PREEMPTIRQ_TRACEPOINTS
    
    Other than the performance tests mentioned in the previous patch, I also
    ran the locking API test suite. I verified that all tests cases are
    passing.
    
    I also injected issues by not registering lockdep probes onto the
    tracepoints and I see failures to confirm that the probes are indeed
    working.
    
    This series + lockdep probes not registered (just to inject errors):
    [    0.000000]      hard-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
    [    0.000000]      soft-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
    [    0.000000]        sirq-safe-A => hirqs-on/12:FAILED|FAILED|  ok  |
    [    0.000000]        sirq-safe-A => hirqs-on/21:FAILED|FAILED|  ok  |
    [    0.000000]          hard-safe-A + irqs-on/12:FAILED|FAILED|  ok  |
    [    0.000000]          soft-safe-A + irqs-on/12:FAILED|FAILED|  ok  |
    [    0.000000]          hard-safe-A + irqs-on/21:FAILED|FAILED|  ok  |
    [    0.000000]          soft-safe-A + irqs-on/21:FAILED|FAILED|  ok  |
    [    0.000000]     hard-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |
    [    0.000000]     soft-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |
    
    With this series + lockdep probes registered, all locking tests pass:
    
    [    0.000000]      hard-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
    [    0.000000]      soft-irqs-on + irq-safe-A/21:  ok  |  ok  |  ok  |
    [    0.000000]        sirq-safe-A => hirqs-on/12:  ok  |  ok  |  ok  |
    [    0.000000]        sirq-safe-A => hirqs-on/21:  ok  |  ok  |  ok  |
    [    0.000000]          hard-safe-A + irqs-on/12:  ok  |  ok  |  ok  |
    [    0.000000]          soft-safe-A + irqs-on/12:  ok  |  ok  |  ok  |
    [    0.000000]          hard-safe-A + irqs-on/21:  ok  |  ok  |  ok  |
    [    0.000000]          soft-safe-A + irqs-on/21:  ok  |  ok  |  ok  |
    [    0.000000]     hard-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |
    [    0.000000]     soft-safe-A + unsafe-B #1/123:  ok  |  ok  |  ok  |
    
    Link: http://lkml.kernel.org/r/20180730222423.196630-4-joel@joelfernandes.orgAcked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: default avatarNamhyung Kim <namhyung@kernel.org>
    Signed-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
    Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
    c3bc8fd6
preempt.h 9.33 KB