On Thu, 1 Feb 2024 03:02:05 +0000 Al Viro <viro@xxxxxxxxxxxxxxxxxx> 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
