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    Subject[PATCH V5 04/20] trace/osnoise: Use start/stop_per_cpu_kthreads() on osnoise_cpus_write()
    Date
    When writing a new CPU mask via osnoise/cpus, if the tracer is running,
    the workload is restarted to follow the new cpumask. The restart is
    currently done using osnoise_workload_start/stop(), which disables the
    workload *and* the instrumentation. However, disabling the
    instrumentation is not necessary.

    Calling start/stop_per_cpu_kthreads() is enough to apply the new
    osnoise/cpus config.

    No functional change.

    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Tom Zanussi <zanussi@kernel.org>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Juri Lelli <juri.lelli@redhat.com>
    Cc: Clark Williams <williams@redhat.com>
    Cc: John Kacur <jkacur@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
    Cc: linux-rt-users@vger.kernel.org
    Cc: linux-trace-devel@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
    ---
    kernel/trace/trace_osnoise.c | 7 ++-----
    1 file changed, 2 insertions(+), 5 deletions(-)

    diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
    index 4381a06af916..7453b96c548b 100644
    --- a/kernel/trace/trace_osnoise.c
    +++ b/kernel/trace/trace_osnoise.c
    @@ -1677,9 +1677,6 @@ osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
    return count;
    }

    -static int osnoise_workload_start(void);
    -static void osnoise_workload_stop(void);
    -
    /*
    * osnoise_cpus_write - Write function for "cpus" entry
    * @filp: The active open file structure
    @@ -1724,7 +1721,7 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
    mutex_lock(&trace_types_lock);
    running = osnoise_busy;
    if (running)
    - osnoise_workload_stop();
    + stop_per_cpu_kthreads();

    mutex_lock(&interface_lock);
    /*
    @@ -1738,7 +1735,7 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
    mutex_unlock(&interface_lock);

    if (running)
    - osnoise_workload_start();
    + start_per_cpu_kthreads();
    mutex_unlock(&trace_types_lock);

    free_cpumask_var(osnoise_cpumask_new);
    --
    2.31.1
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