Re: [PATCH v6 02/13] user_events: Add minimal support for trace_event into ftrace

[Steven Rostedt]

On Thu, 9 Dec 2021 12:11:12 -0800
Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx> wrote:

> I guess I am being paranoid about an architecture that does not have
> automatic cache consistency and while the write / read don't happen at
> the exact time, they happen close together. Close enough that one CPU
> reads the old value from a cache line and gets it wrong.
> 
> I don't believe that is possible on Intel, but I don't know if it's
> possible on other architectures (especially older ones).

If this was possible, then there would be a lot more bugs out there than
this one. For one thing, the file descriptor itself would be freed while
accessed.

-- Steve