This should add race because new PDE for directory will be glued to tree
with NULL ->proc_iops and, at least, vfs_getattr() doesn't check for
I've tried to reproduce this scenario with udelay() inserted before
S_ISDIR checks in proc_register() but got some panic while in X,
so no cookie for me. Maybe it's impossible, indeed.
Anyway, this patch + moving ->proc_fops and ->proc_iops initialization
before gluing is OK with me.