[bug report] Potential atomicity/refcounting issues in 'drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c', between 'cxgb4_clip_get()' and 'cxgb4_clip_release()'

[Ginger]

Dear Linux kernel maintainers,

My research-based static analyzer found a potential
refcounting/atomicity bug within the
'drivers/net/ethernet/chelsio/cxgb4' subsystem, more specifically, in
'drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c'.

Kernel version: long-term kernel v6.18.9

Potential concurrent triggering executions:
T0:
cxgb4_clip_get
     --> read_unlock_bh(&ctbl->lock);
     --> refcount_inc(&ce->refcnt);
or
cxgb4_clip_get
     --> write_unlock_bh(&ctbl->lock);
     --> refcount_set(&ce->refcnt, 1);

T1:
cxgb4_clip_release
    --> write_lock_bh(&ctbl->lock);
    --> spin_lock_bh(&ce->lock);
    --> refcount_dec_and_test(&ce->refcnt);
    --> spin_unlock_bh(&ce->lock);
    --> write_unlock_bh(&ctbl->lock);

In T0, the refcounting increment on 'ce->refcnt' is not operated
within 'ctbl->lock' and or does not check whether the refcount has
already reached zero, i.e., not synchronized with
'cxgb4_clip_release'.
Although 'ctbl->lock' does not seem to protect 'ce->refcnt', this is
potentially problematic because T1 decrements the 'ce->refcnt' using
synchronized locks and refcounting decrement.

Thank you for your time and consideration.

Best regards,
Ginger