From a9839d204896c59b0e2ae08e571515b1cf752bd1 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 5 May 2025 17:21:10 -0400 Subject: [PATCH] tracing: kdb: Use tracer_tracing_on/off() instead of setting per CPU disabled 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 Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Daniel Thompson Reviewed-by: Douglas Anderson Link: https://lore.kernel.org/20250505212235.549033722@goodmis.org Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_kdb.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c index 1e72d20b3c2f..d7b135de958a 100644 --- a/kernel/trace/trace_kdb.c +++ b/kernel/trace/trace_kdb.c @@ -98,7 +98,6 @@ static int kdb_ftdump(int argc, const char **argv) long cpu_file; int err; int cnt; - int cpu; if (argc > 2) return KDB_ARGCOUNT; @@ -120,9 +119,7 @@ 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_disable(iter.tr); /* A negative skip_entries means skip all but the last entries */ if (skip_entries < 0) { @@ -135,9 +132,7 @@ 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_enable(iter.tr); kdb_trap_printk--; -- 2.25.1