On Mon, 29 Jan 2024 16:01:25 -0800
Linus Torvalds [off-list ref] wrote:

I'll go see what's up with the "create it again" case - I don't
immediately see what's wrong.

Interesting. I added a printk in the lookup, and just did this:

 # cd /sys/kernel/tracing
 # ls events/kprobes

And it showed that it tried to see if "kprobes" existed in the lookup.
Which it did not because I haven't created any kprobes yet.

Then I did:

 # echo 'p:sched schedule' >> /sys/kernel/tracing/kprobe_events
 # ls -l events/kprobes/
ls: cannot access 'events/kprobes/': No such file or directory

Where it should now exist but doesn't. But the lookup code never triggered.

If the lookup fails, does it cache the result?

-- Steve