The init_blk_tracer() function causes significant boot delay as it waits for the trace_event_sem lock held by trace_event_update_all(). Specifically, its child function register_trace_event() requires this lock, which is occupied for an extended period during boot.
To mitigate this contention, we have moved init_blk_tracer() to the trace_init_wq workqueue, allowing it to execute asynchronously and prevent blocking the main boot thread. Signed-off-by: Yaxiong Tian <[email protected]> --- kernel/trace/blktrace.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index d031c8d80be4..d611cd1f02ef 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -1832,7 +1832,9 @@ static struct trace_event trace_blk_event = { .funcs = &trace_blk_event_funcs, }; -static int __init init_blk_tracer(void) +static struct work_struct blktrace_works __initdata; + +static int __init __init_blk_tracer(void) { if (!register_trace_event(&trace_blk_event)) { pr_warn("Warning: could not register block events\n"); @@ -1852,6 +1854,25 @@ static int __init init_blk_tracer(void) return 0; } +static void __init blktrace_works_func(struct work_struct *work) +{ + __init_blk_tracer(); +} + +static int __init init_blk_tracer(void) +{ + int ret = 0; + + if (trace_init_wq) { + INIT_WORK(&blktrace_works, blktrace_works_func); + queue_work(trace_init_wq, &blktrace_works); + } else { + ret = __init_blk_tracer(); + } + + return ret; +} + device_initcall(init_blk_tracer); static int blk_trace_remove_queue(struct request_queue *q) -- 2.25.1
