iflib_ctx_lock_get
#define ASSERT_CTX_LOCK_HELD(hw) (sx_assert(iflib_ctx_lock_get(((struct e1000_osdep *)hw->back)->ctx), SX_XLOCKED))
struct sx *iflib_ctx_lock = iflib_ctx_lock_get(sc->ctx);
struct sx *iflib_ctx_lock_get(if_ctx_t);