From: Steven Rostedt <[email protected]> The per CPU "disabled" value was the original way to disable tracing when the tracing subsystem was first created. Today, the ring buffer infrastructure has its own way to disable tracing. In fact, things have changed so much since 2008 that many things ignore the disable flag.
The kdb_ftdump() function iterates over all the current tracing CPUs and increments the "disabled" counter before doing the dump, and decrements it afterward. As the disabled flag can be ignored, doing this today is not reliable. Instead, simply call tracer_tracing_off() and then tracer_tracing_on() to disable and then enabled the entire ring buffer in one go! Cc: Jason Wessel <[email protected]> Cc: Daniel Thompson <[email protected]> Cc: Douglas Anderson <[email protected]> Signed-off-by: Steven Rostedt (Google) <[email protected]> --- kernel/trace/trace_kdb.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c index 1e72d20b3c2f..b5cf3fdde8cb 100644 --- a/kernel/trace/trace_kdb.c +++ b/kernel/trace/trace_kdb.c @@ -120,9 +120,7 @@ static int kdb_ftdump(int argc, const char **argv) trace_init_global_iter(&iter); iter.buffer_iter = buffer_iter; - for_each_tracing_cpu(cpu) { - atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); - } + tracer_tracing_off(iter.tr); /* A negative skip_entries means skip all but the last entries */ if (skip_entries < 0) { @@ -135,9 +133,7 @@ static int kdb_ftdump(int argc, const char **argv) ftrace_dump_buf(skip_entries, cpu_file); - for_each_tracing_cpu(cpu) { - atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); - } + tracer_tracing_on(iter.tr); kdb_trap_printk--; -- 2.47.2
