RDMA/i40iw: Remove MSS change support

MSS change on active QPs is not supported. Store new MSS
value for new QPs only. Remove code to modify MSS on the fly.
This also resolves a crash on QP modify to QP 0.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: i40iw_sc_qp_modify+0x22/0x280 [i40iw]
Oops: 0000 [#1] SMP KASAN
CPU: 2 PID: 1236 Comm: kworker/u16:4 Not tainted 4.12.0-rc1 #5
Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./Q87M-D2H,
BIOS F7 01/17/2014
Workqueue: l2params i40iw_l2params_worker [i40iw]
task: ffff88070f5a9b40 task.stack: ffff88070f5a0000
RIP: 0010:i40iw_sc_qp_modify+0x22/0x280 [i40iw]
...
Call Trace:
i40iw_exec_cqp_cmd+0x2ce/0x410 [i40iw]
? _raw_spin_lock_irqsave+0x6f/0x80
? i40iw_process_cqp_cmd+0x1d/0x80 [i40iw]
i40iw_process_cqp_cmd+0x7c/0x80 [i40iw]
i40iw_handle_cqp_op+0x2f/0x200 [i40iw]
? trace_hardirqs_off+0xd/0x10
? _raw_spin_unlock_irqrestore+0x46/0x50
i40iw_hw_modify_qp+0x5e/0x90 [i40iw]
i40iw_qp_mss_modify+0x52/0x60 [i40iw]
i40iw_change_l2params+0x145/0x160 [i40iw]
i40iw_l2params_worker+0x1f/0x40 [i40iw]
process_one_work+0x1f5/0x650
? process_one_work+0x161/0x650
worker_thread+0x48/0x3b0
kthread+0x112/0x150
? process_one_work+0x650/0x650
? kthread_create_on_node+0x40/0x40
ret_from_fork+0x2e/0x40
Code: 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 56 41 55 41 89 cd 41 54 49 89 fc
53 48 89 f3 48 89 d6 48 83 ec 08 48 8b 87 10 01 00 00 <48> 8b 40 08 4c 8b b0 40 04
00 00 4c 89 f7 e8 1b e5 ff ff 48 85
RIP: i40iw_sc_qp_modify+0x22/0x280 [i40iw] RSP: ffff88070f5a7c28
CR2: 0000000000000008
---[ end trace 77a405931e296060 ]---

Reported-by: Stefan Assmann <sassmann@redhat.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/i40iw/i40iw_ctrl.c

@@ -285,28 +285,20 @@ void i40iw_change_l2params(struct i40iw_sc_vsi *vsi, struct i40iw_l2params *l2pa
 	struct i40iw_sc_dev *dev = vsi->dev;
 	struct i40iw_sc_qp *qp = NULL;
 	bool qs_handle_change = false;
-	bool mss_change = false;
 	unsigned long flags;
 	u16 qs_handle;
 	int i;
 
-	if (vsi->mss != l2params->mss) {
-		mss_change = true;
-		vsi->mss = l2params->mss;
-	}
+	vsi->mss = l2params->mss;
 
 	i40iw_fill_qos_list(l2params->qs_handle_list);
 	for (i = 0; i < I40IW_MAX_USER_PRIORITY; i++) {
 		qs_handle = l2params->qs_handle_list[i];
 		if (vsi->qos[i].qs_handle != qs_handle)
 			qs_handle_change = true;
-		else if (!mss_change)
-			continue;       /* no MSS nor qs handle change */
 		spin_lock_irqsave(&vsi->qos[i].lock, flags);
 		qp = i40iw_get_qp(&vsi->qos[i].qplist, qp);
 		while (qp) {
-			if (mss_change)
-				i40iw_qp_mss_modify(dev, qp);
 			if (qs_handle_change) {
 				qp->qs_handle = qs_handle;
 				/* issue cqp suspend command */
@@ -2395,7 +2387,6 @@ static enum i40iw_status_code i40iw_sc_qp_modify(
 
 	set_64bit_val(wqe,
 		      8,
-		      LS_64(info->new_mss, I40IW_CQPSQ_QP_NEWMSS) |
 		      LS_64(term_len, I40IW_CQPSQ_QP_TERMLEN));
 
 	set_64bit_val(wqe, 16, qp->hw_host_ctx_pa);
@@ -2410,7 +2401,6 @@ static enum i40iw_status_code i40iw_sc_qp_modify(
 		 LS_64(info->cq_num_valid, I40IW_CQPSQ_QP_CQNUMVALID) |
 		 LS_64(info->force_loopback, I40IW_CQPSQ_QP_FORCELOOPBACK) |
 		 LS_64(qp->qp_type, I40IW_CQPSQ_QP_QPTYPE) |
-		 LS_64(info->mss_change, I40IW_CQPSQ_QP_MSSCHANGE) |
 		 LS_64(info->static_rsrc, I40IW_CQPSQ_QP_STATRSRC) |
 		 LS_64(info->remove_hash_idx, I40IW_CQPSQ_QP_REMOVEHASHENTRY) |
 		 LS_64(term_actions, I40IW_CQPSQ_QP_TERMACT) |

drivers/infiniband/hw/i40iw/i40iw_osdep.h

@@ -199,7 +199,6 @@ void i40iw_cqp_spawn_worker(struct i40iw_sc_dev *dev,
 			    struct i40iw_virtchnl_work_info *work_info, u32 iw_vf_idx);
 void *i40iw_remove_head(struct list_head *list);
 void i40iw_qp_suspend_resume(struct i40iw_sc_dev *dev, struct i40iw_sc_qp *qp, bool suspend);
-void i40iw_qp_mss_modify(struct i40iw_sc_dev *dev, struct i40iw_sc_qp *qp);
 
 void i40iw_term_modify_qp(struct i40iw_sc_qp *qp, u8 next_state, u8 term, u8 term_len);
 void i40iw_terminate_done(struct i40iw_sc_qp *qp, int timeout_occurred);

drivers/infiniband/hw/i40iw/i40iw_type.h

@@ -541,7 +541,6 @@ struct i40iw_create_qp_info {
 struct i40iw_modify_qp_info {
 	u64 rx_win0;
 	u64 rx_win1;
-	u16 new_mss;
 	u8 next_iwarp_state;
 	u8 termlen;
 	bool ord_valid;
@@ -554,7 +553,6 @@ struct i40iw_modify_qp_info {
 	bool dont_send_term;
 	bool dont_send_fin;
 	bool cached_var_valid;
-	bool mss_change;
 	bool force_loopback;
 };
 

drivers/infiniband/hw/i40iw/i40iw_utils.c

@@ -756,23 +756,6 @@ void i40iw_qp_suspend_resume(struct i40iw_sc_dev *dev, struct i40iw_sc_qp *qp, b
 		i40iw_pr_err("CQP-OP QP Suspend/Resume fail");
 }
 
-/**
- * i40iw_qp_mss_modify - modify mss for qp
- * @dev: hardware control device structure
- * @qp: hardware control qp
- */
-void i40iw_qp_mss_modify(struct i40iw_sc_dev *dev, struct i40iw_sc_qp *qp)
-{
-	struct i40iw_device *iwdev = (struct i40iw_device *)dev->back_dev;
-	struct i40iw_qp *iwqp = (struct i40iw_qp *)qp->back_qp;
-	struct i40iw_modify_qp_info info;
-
-	memset(&info, 0, sizeof(info));
-	info.mss_change = true;
-	info.new_mss = qp->vsi->mss;
-	i40iw_hw_modify_qp(iwdev, iwqp, &info, false);
-}
-
 /**
  * i40iw_term_modify_qp - modify qp for term message
  * @qp: hardware control qp