Re: [PATCH v4 5/5] blktrace: Make init_blk_tracer() asynchronous when trace_async_init set

Steven Rostedt
2026-01-29T20:29:49Z

On Wed, 28 Jan 2026 19:25:46 -0700
Jens Axboe <axboe@kernel.dk> wrote:

> On Jan 28, 2026, at 5:40 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > ﻿
> > Jens,
> >
> > Can you give me an acked-by on this patch and I can take the series through
> > my tree.
>
> On phone, hope this works:
>
> Acked-by: Jens Axboe <axboe@kernel.dk>

Thanks!

>
> > Or perhaps this doesn't even need to test the trace_async_init flag and can
> > always do the work queue? Does blk_trace ever do tracing at boot up? That
> > is, before user space starts?
>
> Not via the traditonal way of running blktrace.

Masami and Yaxiong,

I've been thinking about this more and I'm not sure we need the
trace_async_init kernel parameter at all. As blktrace should only be
enabled by user space, it can always use the work queue.

For kprobes, if someone is adding a kprobe on the kernel command line, then
they are already specifying that tracing is more important.

Patch 3 already keeps kprobes from being an issue with contention of the
tracing locks, so I don't think it ever needs to use the work queue.

Wouldn't it just be better to remove the trace_async_init and make blktrace
always use the work queue and kprobes never do it (but exit out early if
there were no kprobes registered)?

That is, remove patch 2 and 4 and make this patch always use the work queue.

-- Steve