RDMA: Restore ability to fail on PD deallocate

The IB verbs objects are counted by the kernel and ib_core ensures that
deallocate PD will success so it will be called once all other objects
that depends on PD will be released. This is achieved by managing various
reference counters on such objects.

The mlx5 driver didn't follow this standard flow when allowed DEVX objects
that are not managed by ib_core to be interleaved with the ones under
ib_core responsibility.

In such interleaved scenarios deallocate command can fail and ib_core will
leave uobject in internal DB and attempt to clean it later to free
resources anyway.

This change partially restores returned value from dealloc_pd() for all
drivers, but keeping in mind that non-DEVX devices and kernel verbs paths
shouldn't fail.

Fixes: 21a428a019 ("RDMA: Handle PD allocations by IB/core")
Link: https://lore.kernel.org/r/20200907120921.476363-2-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/uverbs_std_types.c

@@ -122,8 +122,7 @@ static int uverbs_free_pd(struct ib_uobject *uobject,
 	if (ret)
 		return ret;
 
-	ib_dealloc_pd_user(pd, &attrs->driver_udata);
-	return 0;
+	return ib_dealloc_pd_user(pd, &attrs->driver_udata);
 }
 
 void ib_uverbs_free_event_queue(struct ib_uverbs_event_queue *event_queue)

drivers/infiniband/core/verbs.c

@@ -329,7 +329,7 @@ EXPORT_SYMBOL(__ib_alloc_pd);
  * exist.  The caller is responsible to synchronously destroy them and
  * guarantee no new allocations will happen.
  */
-void ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata)
+int ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata)
 {
 	int ret;
 
@@ -343,9 +343,13 @@ void ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata)
 	   requires the caller to guarantee we can't race here. */
 	WARN_ON(atomic_read(&pd->usecnt));
 
+	ret = pd->device->ops.dealloc_pd(pd, udata);
+	if (ret)
+		return ret;
+
 	rdma_restrack_del(&pd->res);
-	pd->device->ops.dealloc_pd(pd, udata);
 	kfree(pd);
+	return ret;
 }
 EXPORT_SYMBOL(ib_dealloc_pd_user);
 

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -532,7 +532,7 @@ fail:
 }
 
 /* Protection Domains */
-void bnxt_re_dealloc_pd(struct ib_pd *ib_pd, struct ib_udata *udata)
+int bnxt_re_dealloc_pd(struct ib_pd *ib_pd, struct ib_udata *udata)
 {
 	struct bnxt_re_pd *pd = container_of(ib_pd, struct bnxt_re_pd, ib_pd);
 	struct bnxt_re_dev *rdev = pd->rdev;
@@ -542,6 +542,7 @@ void bnxt_re_dealloc_pd(struct ib_pd *ib_pd, struct ib_udata *udata)
 	if (pd->qplib_pd.id)
 		bnxt_qplib_dealloc_pd(&rdev->qplib_res, &rdev->qplib_res.pd_tbl,
 				      &pd->qplib_pd);
+	return 0;
 }
 
 int bnxt_re_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)

drivers/infiniband/hw/bnxt_re/ib_verbs.h

@@ -163,7 +163,7 @@ int bnxt_re_query_gid(struct ib_device *ibdev, u8 port_num,
 enum rdma_link_layer bnxt_re_get_link_layer(struct ib_device *ibdev,
 					    u8 port_num);
 int bnxt_re_alloc_pd(struct ib_pd *pd, struct ib_udata *udata);
-void bnxt_re_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
+int bnxt_re_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
 int bnxt_re_create_ah(struct ib_ah *ah, struct rdma_ah_init_attr *init_attr,
 		      struct ib_udata *udata);
 int bnxt_re_modify_ah(struct ib_ah *ah, struct rdma_ah_attr *ah_attr);

drivers/infiniband/hw/cxgb4/provider.c

@@ -190,7 +190,7 @@ static int c4iw_mmap(struct ib_ucontext *context, struct vm_area_struct *vma)
 	return ret;
 }
 
-static void c4iw_deallocate_pd(struct ib_pd *pd, struct ib_udata *udata)
+static int c4iw_deallocate_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	struct c4iw_dev *rhp;
 	struct c4iw_pd *php;
@@ -202,6 +202,7 @@ static void c4iw_deallocate_pd(struct ib_pd *pd, struct ib_udata *udata)
 	mutex_lock(&rhp->rdev.stats.lock);
 	rhp->rdev.stats.pd.cur--;
 	mutex_unlock(&rhp->rdev.stats.lock);
+	return 0;
 }
 
 static int c4iw_allocate_pd(struct ib_pd *pd, struct ib_udata *udata)

drivers/infiniband/hw/efa/efa.h

@@ -134,7 +134,7 @@ int efa_query_gid(struct ib_device *ibdev, u8 port, int index,
 int efa_query_pkey(struct ib_device *ibdev, u8 port, u16 index,
 		   u16 *pkey);
 int efa_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
-void efa_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
+int efa_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
 int efa_destroy_qp(struct ib_qp *ibqp, struct ib_udata *udata);
 struct ib_qp *efa_create_qp(struct ib_pd *ibpd,
 			    struct ib_qp_init_attr *init_attr,

drivers/infiniband/hw/efa/efa_verbs.c

@@ -383,13 +383,14 @@ err_out:
 	return err;
 }
 
-void efa_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
+int efa_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 {
 	struct efa_dev *dev = to_edev(ibpd->device);
 	struct efa_pd *pd = to_epd(ibpd);
 
 	ibdev_dbg(&dev->ibdev, "Dealloc pd[%d]\n", pd->pdn);
 	efa_pd_dealloc(dev, pd->pdn);
+	return 0;
 }
 
 static int efa_destroy_qp_handle(struct efa_dev *dev, u32 qp_handle)

drivers/infiniband/hw/hns/hns_roce_device.h

@@ -1182,7 +1182,7 @@ int hns_roce_query_ah(struct ib_ah *ibah, struct rdma_ah_attr *ah_attr);
 void hns_roce_destroy_ah(struct ib_ah *ah, u32 flags);
 
 int hns_roce_alloc_pd(struct ib_pd *pd, struct ib_udata *udata);
-void hns_roce_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
+int hns_roce_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
 
 struct ib_mr *hns_roce_get_dma_mr(struct ib_pd *pd, int acc);
 struct ib_mr *hns_roce_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,

drivers/infiniband/hw/hns/hns_roce_pd.c

@@ -82,9 +82,10 @@ int hns_roce_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return 0;
 }
 
-void hns_roce_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+int hns_roce_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	hns_roce_pd_free(to_hr_dev(pd->device), to_hr_pd(pd)->pdn);
+	return 0;
 }
 
 int hns_roce_uar_alloc(struct hns_roce_dev *hr_dev, struct hns_roce_uar *uar)

drivers/infiniband/hw/i40iw/i40iw_verbs.c

@@ -328,12 +328,13 @@ error:
  * @ibpd: ptr of pd to be deallocated
  * @udata: user data or null for kernel object
  */
-static void i40iw_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
+static int i40iw_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 {
 	struct i40iw_pd *iwpd = to_iwpd(ibpd);
 	struct i40iw_device *iwdev = to_iwdev(ibpd->device);
 
 	i40iw_rem_pdusecount(iwpd, iwdev);
+	return 0;
 }
 
 /**

drivers/infiniband/hw/mlx4/main.c

@@ -1214,9 +1214,10 @@ static int mlx4_ib_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return 0;
 }
 
-static void mlx4_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+static int mlx4_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	mlx4_pd_free(to_mdev(pd->device)->dev, to_mpd(pd)->pdn);
+	return 0;
 }
 
 static int mlx4_ib_alloc_xrcd(struct ib_xrcd *ibxrcd, struct ib_udata *udata)

drivers/infiniband/hw/mlx5/cmd.c

@@ -209,14 +209,14 @@ void mlx5_cmd_dealloc_transport_domain(struct mlx5_core_dev *dev, u32 tdn,
 	mlx5_cmd_exec_in(dev, dealloc_transport_domain, in);
 }
 
-void mlx5_cmd_dealloc_pd(struct mlx5_core_dev *dev, u32 pdn, u16 uid)
+int mlx5_cmd_dealloc_pd(struct mlx5_core_dev *dev, u32 pdn, u16 uid)
 {
 	u32 in[MLX5_ST_SZ_DW(dealloc_pd_in)] = {};
 
 	MLX5_SET(dealloc_pd_in, in, opcode, MLX5_CMD_OP_DEALLOC_PD);
 	MLX5_SET(dealloc_pd_in, in, pd, pdn);
 	MLX5_SET(dealloc_pd_in, in, uid, uid);
-	mlx5_cmd_exec_in(dev, dealloc_pd, in);
+	return mlx5_cmd_exec_in(dev, dealloc_pd, in);
 }
 
 int mlx5_cmd_attach_mcg(struct mlx5_core_dev *dev, union ib_gid *mgid,

drivers/infiniband/hw/mlx5/cmd.h

@@ -44,7 +44,7 @@ int mlx5_cmd_query_cong_params(struct mlx5_core_dev *dev, int cong_point,
 int mlx5_cmd_alloc_memic(struct mlx5_dm *dm, phys_addr_t *addr,
 			 u64 length, u32 alignment);
 void mlx5_cmd_dealloc_memic(struct mlx5_dm *dm, phys_addr_t addr, u64 length);
-void mlx5_cmd_dealloc_pd(struct mlx5_core_dev *dev, u32 pdn, u16 uid);
+int mlx5_cmd_dealloc_pd(struct mlx5_core_dev *dev, u32 pdn, u16 uid);
 void mlx5_cmd_destroy_tir(struct mlx5_core_dev *dev, u32 tirn, u16 uid);
 void mlx5_cmd_destroy_tis(struct mlx5_core_dev *dev, u32 tisn, u16 uid);
 void mlx5_cmd_destroy_rqt(struct mlx5_core_dev *dev, u32 rqtn, u16 uid);

drivers/infiniband/hw/mlx5/main.c

@@ -2569,12 +2569,12 @@ static int mlx5_ib_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return 0;
 }
 
-static void mlx5_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+static int mlx5_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	struct mlx5_ib_dev *mdev = to_mdev(pd->device);
 	struct mlx5_ib_pd *mpd = to_mpd(pd);
 
-	mlx5_cmd_dealloc_pd(mdev->mdev, mpd->pdn, mpd->uid);
+	return mlx5_cmd_dealloc_pd(mdev->mdev, mpd->pdn, mpd->uid);
 }
 
 static int mlx5_ib_mcg_attach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)

drivers/infiniband/hw/mthca/mthca_provider.c

@@ -373,9 +373,10 @@ static int mthca_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return 0;
 }
 
-static void mthca_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+static int mthca_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	mthca_pd_free(to_mdev(pd->device), to_mpd(pd));
+	return 0;
 }
 
 static int mthca_ah_create(struct ib_ah *ibah,

drivers/infiniband/hw/ocrdma/ocrdma_verbs.c

@@ -664,7 +664,7 @@ exit:
 	return status;
 }
 
-void ocrdma_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
+int ocrdma_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 {
 	struct ocrdma_pd *pd = get_ocrdma_pd(ibpd);
 	struct ocrdma_dev *dev = get_ocrdma_dev(ibpd->device);
@@ -682,10 +682,11 @@ void ocrdma_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 
 		if (is_ucontext_pd(uctx, pd)) {
 			ocrdma_release_ucontext_pd(uctx);
-			return;
+			return 0;
 		}
 	}
 	_ocrdma_dealloc_pd(dev, pd);
+	return 0;
 }
 
 static int ocrdma_alloc_lkey(struct ocrdma_dev *dev, struct ocrdma_mr *mr,

drivers/infiniband/hw/ocrdma/ocrdma_verbs.h

@@ -67,7 +67,7 @@ void ocrdma_dealloc_ucontext(struct ib_ucontext *uctx);
 int ocrdma_mmap(struct ib_ucontext *, struct vm_area_struct *vma);
 
 int ocrdma_alloc_pd(struct ib_pd *pd, struct ib_udata *udata);
-void ocrdma_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
+int ocrdma_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
 
 int ocrdma_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
 		     struct ib_udata *udata);

drivers/infiniband/hw/qedr/verbs.c

@@ -471,13 +471,14 @@ int qedr_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return 0;
 }
 
-void qedr_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
+int qedr_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 {
 	struct qedr_dev *dev = get_qedr_dev(ibpd->device);
 	struct qedr_pd *pd = get_qedr_pd(ibpd);
 
 	DP_DEBUG(dev, QEDR_MSG_INIT, "Deallocating PD %d\n", pd->pd_id);
 	dev->ops->rdma_dealloc_pd(dev->rdma_ctx, pd->pd_id);
+	return 0;
 }
 
 static void qedr_free_pbl(struct qedr_dev *dev,

drivers/infiniband/hw/qedr/verbs.h

@@ -47,7 +47,7 @@ void qedr_dealloc_ucontext(struct ib_ucontext *uctx);
 int qedr_mmap(struct ib_ucontext *ucontext, struct vm_area_struct *vma);
 void qedr_mmap_free(struct rdma_user_mmap_entry *rdma_entry);
 int qedr_alloc_pd(struct ib_pd *pd, struct ib_udata *udata);
-void qedr_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
+int qedr_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
 
 int qedr_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
 		   struct ib_udata *udata);

drivers/infiniband/hw/usnic/usnic_ib_verbs.c

@@ -449,9 +449,10 @@ int usnic_ib_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return 0;
 }
 
-void usnic_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+int usnic_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	usnic_uiom_dealloc_pd((to_upd(pd))->umem_pd);
+	return 0;
 }
 
 struct ib_qp *usnic_ib_create_qp(struct ib_pd *pd,

drivers/infiniband/hw/usnic/usnic_ib_verbs.h

@@ -49,7 +49,7 @@ int usnic_ib_query_qp(struct ib_qp *qp, struct ib_qp_attr *qp_attr,
 int usnic_ib_query_gid(struct ib_device *ibdev, u8 port, int index,
 				union ib_gid *gid);
 int usnic_ib_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
-void usnic_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
+int usnic_ib_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata);
 struct ib_qp *usnic_ib_create_qp(struct ib_pd *pd,
 					struct ib_qp_init_attr *init_attr,
 					struct ib_udata *udata);

drivers/infiniband/hw/vmw_pvrdma/pvrdma_verbs.c

@@ -479,9 +479,9 @@ err:
  * @pd: the protection domain to be released
  * @udata: user data or null for kernel object
  *
- * @return: 0 on success, otherwise errno.
+ * @return: Always 0
  */
-void pvrdma_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+int pvrdma_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	struct pvrdma_dev *dev = to_vdev(pd->device);
 	union pvrdma_cmd_req req = {};
@@ -498,6 +498,7 @@ void pvrdma_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 			 ret);
 
 	atomic_dec(&dev->num_pds);
+	return 0;
 }
 
 /**

drivers/infiniband/hw/vmw_pvrdma/pvrdma_verbs.h

@@ -399,7 +399,7 @@ int pvrdma_mmap(struct ib_ucontext *context, struct vm_area_struct *vma);
 int pvrdma_alloc_ucontext(struct ib_ucontext *uctx, struct ib_udata *udata);
 void pvrdma_dealloc_ucontext(struct ib_ucontext *context);
 int pvrdma_alloc_pd(struct ib_pd *pd, struct ib_udata *udata);
-void pvrdma_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
+int pvrdma_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
 struct ib_mr *pvrdma_get_dma_mr(struct ib_pd *pd, int acc);
 struct ib_mr *pvrdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
 				 u64 virt_addr, int access_flags,

drivers/infiniband/sw/rdmavt/pd.c

@@ -95,11 +95,12 @@ bail:
  *
  * Return: always 0
  */
-void rvt_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
+int rvt_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 {
 	struct rvt_dev_info *dev = ib_to_rvt(ibpd->device);
 
 	spin_lock(&dev->n_pds_lock);
 	dev->n_pds_allocated--;
 	spin_unlock(&dev->n_pds_lock);
+	return 0;
 }

drivers/infiniband/sw/rdmavt/pd.h

@@ -51,6 +51,6 @@
 #include <rdma/rdma_vt.h>
 
 int rvt_alloc_pd(struct ib_pd *pd, struct ib_udata *udata);
-void rvt_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
+int rvt_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata);
 
 #endif          /* DEF_RDMAVTPD_H */

drivers/infiniband/sw/rxe/rxe_verbs.c

@@ -148,11 +148,12 @@ static int rxe_alloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 	return rxe_add_to_pool(&rxe->pd_pool, &pd->pelem);
 }
 
-static void rxe_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
+static int rxe_dealloc_pd(struct ib_pd *ibpd, struct ib_udata *udata)
 {
 	struct rxe_pd *pd = to_rpd(ibpd);
 
 	rxe_drop_ref(pd);
+	return 0;
 }
 
 static int rxe_create_ah(struct ib_ah *ibah,

drivers/infiniband/sw/siw/siw_verbs.c

@@ -234,12 +234,13 @@ int siw_alloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 	return 0;
 }
 
-void siw_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
+int siw_dealloc_pd(struct ib_pd *pd, struct ib_udata *udata)
 {
 	struct siw_device *sdev = to_siw_dev(pd->device);
 
 	siw_dbg_pd(pd, "free PD\n");
 	atomic_dec(&sdev->num_pd);
+	return 0;
 }
 
 void siw_qp_get_ref(struct ib_qp *base_qp)

drivers/infiniband/sw/siw/siw_verbs.h

@@ -49,7 +49,7 @@ int siw_query_port(struct ib_device *base_dev, u8 port,
 int siw_query_gid(struct ib_device *base_dev, u8 port, int idx,
 		  union ib_gid *gid);
 int siw_alloc_pd(struct ib_pd *base_pd, struct ib_udata *udata);
-void siw_dealloc_pd(struct ib_pd *base_pd, struct ib_udata *udata);
+int siw_dealloc_pd(struct ib_pd *base_pd, struct ib_udata *udata);
 struct ib_qp *siw_create_qp(struct ib_pd *base_pd,
 			    struct ib_qp_init_attr *attr,
 			    struct ib_udata *udata);

include/rdma/ib_verbs.h

@@ -2398,7 +2398,7 @@ struct ib_device_ops {
 	void (*mmap_free)(struct rdma_user_mmap_entry *entry);
 	void (*disassociate_ucontext)(struct ib_ucontext *ibcontext);
 	int (*alloc_pd)(struct ib_pd *pd, struct ib_udata *udata);
-	void (*dealloc_pd)(struct ib_pd *pd, struct ib_udata *udata);
+	int (*dealloc_pd)(struct ib_pd *pd, struct ib_udata *udata);
 	int (*create_ah)(struct ib_ah *ah, struct rdma_ah_init_attr *attr,
 			 struct ib_udata *udata);
 	int (*modify_ah)(struct ib_ah *ah, struct rdma_ah_attr *ah_attr);
@@ -3456,12 +3456,7 @@ struct ib_pd *__ib_alloc_pd(struct ib_device *device, unsigned int flags,
 #define ib_alloc_pd(device, flags) \
 	__ib_alloc_pd((device), (flags), KBUILD_MODNAME)
 
-/**
- * ib_dealloc_pd_user - Deallocate kernel/user PD
- * @pd: The protection domain
- * @udata: Valid user data or NULL for kernel objects
- */
-void ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata);
+int ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata);
 
 /**
  * ib_dealloc_pd - Deallocate kernel PD
@@ -3471,7 +3466,9 @@ void ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata);
  */
 static inline void ib_dealloc_pd(struct ib_pd *pd)
 {
-	ib_dealloc_pd_user(pd, NULL);
+	int ret = ib_dealloc_pd_user(pd, NULL);
+
+	WARN_ONCE(ret, "Destroy of kernel PD shouldn't fail");
 }
 
 enum rdma_create_ah_flags {