Re: [EXTERNAL] Re: audit: io_uring openat triggers audit reference count underflow in worker thread

[Dan Clash]

I retested with the following change as a sanity check:

-       BUG_ON(name->refcnt <= 0);
+       BUG_ON(atomic_read(&name->refcnt) <= 0);

checkpatch.pl suggests using WARN_ON_ONCE rather than BUG.

devvm ~ $ ~/linux/scripts/checkpatch.pl --patch ~/io_uring_audit_hang_atomic.patch 
WARNING: Do not crash the kernel unless it is absolutely unavoidable
  --use WARN_ON_ONCE() plus recovery code (if feasible) instead of BUG() or variants
#28: FILE: fs/namei.c:262:
+       BUG_ON(atomic_read(&name->refcnt) <= 0);
...

refcount_t uses WARN_ON_ONCE.

I can think of three choices:

1. Use atomic_t and remove the BUG line.
2. Use refcount_t and remove the BUG line. 
3. Use atomic_t and partially implement the warn behavior of refcount_t.

Choice 1 and 2 seem better than choice 3.