• Daniel Bristot de Oliveira's avatar
    rv/monitor: Add the wip monitor · 10bde81c
    Daniel Bristot de Oliveira authored
    The wakeup in preemptive (wip) monitor verifies if the
    wakeup events always take place with preemption disabled:
    
                         |
                         |
                         v
                       #==================#
                       H    preemptive    H <+
                       #==================#  |
                         |                   |
                         | preempt_disable   | preempt_enable
                         v                   |
        sched_waking   +------------------+  |
      +--------------- |                  |  |
      |                |  non_preemptive  |  |
      +--------------> |                  | -+
                       +------------------+
    
    The wakeup event always takes place with preemption disabled because
    of the scheduler synchronization. However, because the preempt_count
    and its trace event are not atomic with regard to interrupts, some
    inconsistencies might happen.
    
    The documentation illustrates one of these cases.
    
    Link: https://lkml.kernel.org/r/c98ca678df81115fddc04921b3c79720c836b18f.1659052063.git.bristot@kernel.org
    
    Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
    Cc: Guenter Roeck <linux@roeck-us.net>
    Cc: Jonathan Corbet <corbet@lwn.net>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Will Deacon <will@kernel.org>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Marco Elver <elver@google.com>
    Cc: Dmitry Vyukov <dvyukov@google.com>
    Cc: "Paul E. McKenney" <paulmck@kernel.org>
    Cc: Shuah Khan <skhan@linuxfoundation.org>
    Cc: Gabriele Paoloni <gpaoloni@redhat.com>
    Cc: Juri Lelli <juri.lelli@redhat.com>
    Cc: Clark Williams <williams@redhat.com>
    Cc: Tao Zhou <tao.zhou@linux.dev>
    Cc: Randy Dunlap <rdunlap@infradead.org>
    Cc: linux-doc@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Cc: linux-trace-devel@vger.kernel.org
    Signed-off-by: default avatarDaniel Bristot de Oliveira <bristot@kernel.org>
    Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
    10bde81c
wip.c 2.02 KB