On Thu, 1 Feb 2024 03:02:05 +0000
Al Viro <v...@zeniv.linux.org.uk> wrote:
> > We had a problem here with just returning NULL. It leaves the negative
> > dentry around and doesn't get refreshed.
>
> Why would that dentry stick around? And how would anyone find
> it, anyway, when it's not hashed?
We (Linus and I) got it wrong. It originally had:
d_add(dentry, NULL);
[..]
return NULL;
and it caused the:
# ls events/kprobes/sched/
ls: cannot access 'events/kprobes/sched/': No such file or directory
# echo 'p:sched schedule' >> /sys/kernel/tracing/kprobe_events
# ls events/kprobes/sched/
ls: cannot access 'events/kprobes/sched/': No such file or directory
I just changed the code to simply return NULL, and it had no issues:
# ls events/kprobes/sched/
ls: cannot access 'events/kprobes/sched/': No such file or directory
# echo 'p:sched schedule' >> /sys/kernel/tracing/kprobe_events
# ls events/kprobes/sched/
enable filter format hist hist_debug id inject trigger
But then I added the: d_add(dentry, NULL); that we originally had, and then
it caused the issue again.
So it wasn't the returning NULL that was causing a problem, it was calling
the d_add(dentry, NULL); that was.
I'll update the patch.
-- Steve
