RDMA/bnxt_re: Fix system crash during RDMA resource initialization

bnxt_re_ib_reg acquires and releases the rtnl lock whenever it accesses
the L2 driver.

The following sequence can trigger a crash

Acquires the rtnl_lock ->
	Registers roce driver callback with L2 driver ->
		release the rtnl lock
bnxt_re acquires the rtnl_lock ->
	Request for MSIx vectors ->
		release the rtnl_lock

Issue happens when bnxt_re proceeds with remaining part of initialization
and L2 driver invokes bnxt_ulp_irq_stop as a part of bnxt_open_nic.

The crash is in bnxt_qplib_nq_stop_irq as the NQ structures are
not initialized yet,

<snip>
[ 3551.726647] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 3551.726656] IP: [<ffffffffc0840ee9>] bnxt_qplib_nq_stop_irq+0x59/0xb0 [bnxt_re]
[ 3551.726674] PGD 0
[ 3551.726679] Oops: 0002 1 SMP
...
[ 3551.726822] Hardware name: Dell Inc. PowerEdge R720/08RW36, BIOS 2.4.3 07/09/2014
[ 3551.726826] task: ffff97e30eec5ee0 ti: ffff97e3173bc000 task.ti: ffff97e3173bc000
[ 3551.726829] RIP: 0010:[<ffffffffc0840ee9>] [<ffffffffc0840ee9>]
bnxt_qplib_nq_stop_irq+0x59/0xb0 [bnxt_re]
...
[ 3551.726872] Call Trace:
[ 3551.726886] [<ffffffffc082cb9e>] bnxt_re_stop_irq+0x4e/0x70 [bnxt_re]
[ 3551.726899] [<ffffffffc07d6a53>] bnxt_ulp_irq_stop+0x43/0x70 [bnxt_en]
[ 3551.726908] [<ffffffffc07c82f4>] bnxt_reserve_rings+0x174/0x1e0 [bnxt_en]
[ 3551.726917] [<ffffffffc07cafd8>] __bnxt_open_nic+0x368/0x9a0 [bnxt_en]
[ 3551.726925] [<ffffffffc07cb62b>] bnxt_open_nic+0x1b/0x50 [bnxt_en]
[ 3551.726934] [<ffffffffc07cc62f>] bnxt_setup_mq_tc+0x11f/0x260 [bnxt_en]
[ 3551.726943] [<ffffffffc07d5f58>] bnxt_dcbnl_ieee_setets+0xb8/0x1f0 [bnxt_en]
[ 3551.726954] [<ffffffff890f983a>] dcbnl_ieee_set+0x9a/0x250
[ 3551.726966] [<ffffffff88fd6d21>] ? __alloc_skb+0xa1/0x2d0
[ 3551.726972] [<ffffffff890f72fa>] dcb_doit+0x13a/0x210
[ 3551.726981] [<ffffffff89003ff7>] rtnetlink_rcv_msg+0xa7/0x260
[ 3551.726989] [<ffffffff88ffdb00>] ? rtnl_unicast+0x20/0x30
[ 3551.726996] [<ffffffff88bf9dc8>] ? __kmalloc_node_track_caller+0x58/0x290
[ 3551.727002] [<ffffffff890f7326>] ? dcb_doit+0x166/0x210
[ 3551.727007] [<ffffffff88fd6d0d>] ? __alloc_skb+0x8d/0x2d0
[ 3551.727012] [<ffffffff89003f50>] ? rtnl_newlink+0x880/0x880
...
[ 3551.727104] [<ffffffff8911f7d5>] system_call_fastpath+0x1c/0x21
...
[ 3551.727164] RIP [<ffffffffc0840ee9>] bnxt_qplib_nq_stop_irq+0x59/0xb0 [bnxt_re]
[ 3551.727175] RSP <ffff97e3173bf788>
[ 3551.727177] CR2: 0000000000000000

Avoid this inconsistent state and  system crash by acquiring
the rtnl lock for the entire duration of device initialization.
Re-factor the code to remove the rtnl lock from the individual function
and acquire and release it from the caller.

Fixes: 1ac5a404 ("RDMA/bnxt_re: Add bnxt_re RoCE driver")
Fixes: 6e04b103 ("RDMA/bnxt_re: Fix broken RoCE driver due to recent L2 driver changes")
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/bnxt_re/main.c

@@ -78,7 +78,7 @@ static struct list_head bnxt_re_dev_list = LIST_HEAD_INIT(bnxt_re_dev_list);
 /* Mutex to protect the list of bnxt_re devices added */
 static DEFINE_MUTEX(bnxt_re_dev_lock);
 static struct workqueue_struct *bnxt_re_wq;
-static void bnxt_re_ib_unreg(struct bnxt_re_dev *rdev, bool lock_wait);
+static void bnxt_re_ib_unreg(struct bnxt_re_dev *rdev);
 
 /* SR-IOV helper functions */
 
@@ -182,7 +182,7 @@ static void bnxt_re_shutdown(void *p)
 	if (!rdev)
 		return;
 
-	bnxt_re_ib_unreg(rdev, false);
+	bnxt_re_ib_unreg(rdev);
 }
 
 static void bnxt_re_stop_irq(void *handle)
@@ -251,7 +251,7 @@ static struct bnxt_ulp_ops bnxt_re_ulp_ops = {
 /* Driver registration routines used to let the networking driver (bnxt_en)
  * to know that the RoCE driver is now installed
  */
-static int bnxt_re_unregister_netdev(struct bnxt_re_dev *rdev, bool lock_wait)
+static int bnxt_re_unregister_netdev(struct bnxt_re_dev *rdev)
 {
 	struct bnxt_en_dev *en_dev;
 	int rc;
@@ -260,14 +260,9 @@ static int bnxt_re_unregister_netdev(struct bnxt_re_dev *rdev, bool lock_wait)
 		return -EINVAL;
 
 	en_dev = rdev->en_dev;
-	/* Acquire rtnl lock if it is not invokded from netdev event */
-	if (lock_wait)
-		rtnl_lock();
 
 	rc = en_dev->en_ops->bnxt_unregister_device(rdev->en_dev,
 						    BNXT_ROCE_ULP);
-	if (lock_wait)
-		rtnl_unlock();
 	return rc;
 }
 
@@ -281,14 +276,12 @@ static int bnxt_re_register_netdev(struct bnxt_re_dev *rdev)
 
 	en_dev = rdev->en_dev;
 
-	rtnl_lock();
 	rc = en_dev->en_ops->bnxt_register_device(en_dev, BNXT_ROCE_ULP,
 						  &bnxt_re_ulp_ops, rdev);
-	rtnl_unlock();
 	return rc;
 }
 
-static int bnxt_re_free_msix(struct bnxt_re_dev *rdev, bool lock_wait)
+static int bnxt_re_free_msix(struct bnxt_re_dev *rdev)
 {
 	struct bnxt_en_dev *en_dev;
 	int rc;
@@ -298,13 +291,9 @@ static int bnxt_re_free_msix(struct bnxt_re_dev *rdev, bool lock_wait)
 
 	en_dev = rdev->en_dev;
 
-	if (lock_wait)
-		rtnl_lock();
 
 	rc = en_dev->en_ops->bnxt_free_msix(rdev->en_dev, BNXT_ROCE_ULP);
 
-	if (lock_wait)
-		rtnl_unlock();
 	return rc;
 }
 
@@ -320,7 +309,6 @@ static int bnxt_re_request_msix(struct bnxt_re_dev *rdev)
 
 	num_msix_want = min_t(u32, BNXT_RE_MAX_MSIX, num_online_cpus());
 
-	rtnl_lock();
 	num_msix_got = en_dev->en_ops->bnxt_request_msix(en_dev, BNXT_ROCE_ULP,
 							 rdev->msix_entries,
 							 num_msix_want);
@@ -335,7 +323,6 @@ static int bnxt_re_request_msix(struct bnxt_re_dev *rdev)
 	}
 	rdev->num_msix = num_msix_got;
 done:
-	rtnl_unlock();
 	return rc;
 }
 
@@ -358,24 +345,18 @@ static void bnxt_re_fill_fw_msg(struct bnxt_fw_msg *fw_msg, void *msg,
 	fw_msg->timeout = timeout;
 }
 
-static int bnxt_re_net_ring_free(struct bnxt_re_dev *rdev, u16 fw_ring_id,
-				 bool lock_wait)
+static int bnxt_re_net_ring_free(struct bnxt_re_dev *rdev, u16 fw_ring_id)
 {
 	struct bnxt_en_dev *en_dev = rdev->en_dev;
 	struct hwrm_ring_free_input req = {0};
 	struct hwrm_ring_free_output resp;
 	struct bnxt_fw_msg fw_msg;
-	bool do_unlock = false;
 	int rc = -EINVAL;
 
 	if (!en_dev)
 		return rc;
 
 	memset(&fw_msg, 0, sizeof(fw_msg));
-	if (lock_wait) {
-		rtnl_lock();
-		do_unlock = true;
-	}
 
 	bnxt_re_init_hwrm_hdr(rdev, (void *)&req, HWRM_RING_FREE, -1, -1);
 	req.ring_type = RING_ALLOC_REQ_RING_TYPE_L2_CMPL;
@@ -386,8 +367,6 @@ static int bnxt_re_net_ring_free(struct bnxt_re_dev *rdev, u16 fw_ring_id,
 	if (rc)
 		dev_err(rdev_to_dev(rdev),
 			"Failed to free HW ring:%d :%#x", req.ring_id, rc);
-	if (do_unlock)
-		rtnl_unlock();
 	return rc;
 }
 
@@ -405,7 +384,6 @@ static int bnxt_re_net_ring_alloc(struct bnxt_re_dev *rdev, dma_addr_t *dma_arr,
 		return rc;
 
 	memset(&fw_msg, 0, sizeof(fw_msg));
-	rtnl_lock();
 	bnxt_re_init_hwrm_hdr(rdev, (void *)&req, HWRM_RING_ALLOC, -1, -1);
 	req.enables = 0;
 	req.page_tbl_addr =  cpu_to_le64(dma_arr[0]);
@@ -426,27 +404,21 @@ static int bnxt_re_net_ring_alloc(struct bnxt_re_dev *rdev, dma_addr_t *dma_arr,
 	if (!rc)
 		*fw_ring_id = le16_to_cpu(resp.ring_id);
 
-	rtnl_unlock();
 	return rc;
 }
 
 static int bnxt_re_net_stats_ctx_free(struct bnxt_re_dev *rdev,
-				      u32 fw_stats_ctx_id, bool lock_wait)
+				      u32 fw_stats_ctx_id)
 {
 	struct bnxt_en_dev *en_dev = rdev->en_dev;
 	struct hwrm_stat_ctx_free_input req = {0};
 	struct bnxt_fw_msg fw_msg;
-	bool do_unlock = false;
 	int rc = -EINVAL;
 
 	if (!en_dev)
 		return rc;
 
 	memset(&fw_msg, 0, sizeof(fw_msg));
-	if (lock_wait) {
-		rtnl_lock();
-		do_unlock = true;
-	}
 
 	bnxt_re_init_hwrm_hdr(rdev, (void *)&req, HWRM_STAT_CTX_FREE, -1, -1);
 	req.stat_ctx_id = cpu_to_le32(fw_stats_ctx_id);
@@ -457,8 +429,6 @@ static int bnxt_re_net_stats_ctx_free(struct bnxt_re_dev *rdev,
 		dev_err(rdev_to_dev(rdev),
 			"Failed to free HW stats context %#x", rc);
 
-	if (do_unlock)
-		rtnl_unlock();
 	return rc;
 }
 
@@ -478,7 +448,6 @@ static int bnxt_re_net_stats_ctx_alloc(struct bnxt_re_dev *rdev,
 		return rc;
 
 	memset(&fw_msg, 0, sizeof(fw_msg));
-	rtnl_lock();
 
 	bnxt_re_init_hwrm_hdr(rdev, (void *)&req, HWRM_STAT_CTX_ALLOC, -1, -1);
 	req.update_period_ms = cpu_to_le32(1000);
@@ -490,7 +459,6 @@ static int bnxt_re_net_stats_ctx_alloc(struct bnxt_re_dev *rdev,
 	if (!rc)
 		*fw_stats_ctx_id = le32_to_cpu(resp.stat_ctx_id);
 
-	rtnl_unlock();
 	return rc;
 }
 
@@ -929,19 +897,19 @@ static int bnxt_re_init_res(struct bnxt_re_dev *rdev)
 	return rc;
 }
 
-static void bnxt_re_free_nq_res(struct bnxt_re_dev *rdev, bool lock_wait)
+static void bnxt_re_free_nq_res(struct bnxt_re_dev *rdev)
 {
 	int i;
 
 	for (i = 0; i < rdev->num_msix - 1; i++) {
-		bnxt_re_net_ring_free(rdev, rdev->nq[i].ring_id, lock_wait);
+		bnxt_re_net_ring_free(rdev, rdev->nq[i].ring_id);
 		bnxt_qplib_free_nq(&rdev->nq[i]);
 	}
 }
 
-static void bnxt_re_free_res(struct bnxt_re_dev *rdev, bool lock_wait)
+static void bnxt_re_free_res(struct bnxt_re_dev *rdev)
 {
-	bnxt_re_free_nq_res(rdev, lock_wait);
+	bnxt_re_free_nq_res(rdev);
 
 	if (rdev->qplib_res.dpi_tbl.max) {
 		bnxt_qplib_dealloc_dpi(&rdev->qplib_res,
@@ -1219,7 +1187,7 @@ static int bnxt_re_setup_qos(struct bnxt_re_dev *rdev)
 	return 0;
 }
 
-static void bnxt_re_ib_unreg(struct bnxt_re_dev *rdev, bool lock_wait)
+static void bnxt_re_ib_unreg(struct bnxt_re_dev *rdev)
 {
 	int i, rc;
 
@@ -1234,28 +1202,27 @@ static void bnxt_re_ib_unreg(struct bnxt_re_dev *rdev, bool lock_wait)
 		cancel_delayed_work(&rdev->worker);
 
 	bnxt_re_cleanup_res(rdev);
-	bnxt_re_free_res(rdev, lock_wait);
+	bnxt_re_free_res(rdev);
 
 	if (test_and_clear_bit(BNXT_RE_FLAG_RCFW_CHANNEL_EN, &rdev->flags)) {
 		rc = bnxt_qplib_deinit_rcfw(&rdev->rcfw);
 		if (rc)
 			dev_warn(rdev_to_dev(rdev),
 				 "Failed to deinitialize RCFW: %#x", rc);
-		bnxt_re_net_stats_ctx_free(rdev, rdev->qplib_ctx.stats.fw_id,
-					   lock_wait);
+		bnxt_re_net_stats_ctx_free(rdev, rdev->qplib_ctx.stats.fw_id);
 		bnxt_qplib_free_ctx(rdev->en_dev->pdev, &rdev->qplib_ctx);
 		bnxt_qplib_disable_rcfw_channel(&rdev->rcfw);
-		bnxt_re_net_ring_free(rdev, rdev->rcfw.creq_ring_id, lock_wait);
+		bnxt_re_net_ring_free(rdev, rdev->rcfw.creq_ring_id);
 		bnxt_qplib_free_rcfw_channel(&rdev->rcfw);
 	}
 	if (test_and_clear_bit(BNXT_RE_FLAG_GOT_MSIX, &rdev->flags)) {
-		rc = bnxt_re_free_msix(rdev, lock_wait);
+		rc = bnxt_re_free_msix(rdev);
 		if (rc)
 			dev_warn(rdev_to_dev(rdev),
 				 "Failed to free MSI-X vectors: %#x", rc);
 	}
 	if (test_and_clear_bit(BNXT_RE_FLAG_NETDEV_REGISTERED, &rdev->flags)) {
-		rc = bnxt_re_unregister_netdev(rdev, lock_wait);
+		rc = bnxt_re_unregister_netdev(rdev);
 		if (rc)
 			dev_warn(rdev_to_dev(rdev),
 				 "Failed to unregister with netdev: %#x", rc);
@@ -1276,6 +1243,12 @@ static int bnxt_re_ib_reg(struct bnxt_re_dev *rdev)
 {
 	int i, j, rc;
 
+	bool locked;
+
+	/* Acquire rtnl lock through out this function */
+	rtnl_lock();
+	locked = true;
+
 	/* Registered a new RoCE device instance to netdev */
 	rc = bnxt_re_register_netdev(rdev);
 	if (rc) {
@@ -1374,12 +1347,16 @@ static int bnxt_re_ib_reg(struct bnxt_re_dev *rdev)
 		schedule_delayed_work(&rdev->worker, msecs_to_jiffies(30000));
 	}
 
+	rtnl_unlock();
+	locked = false;
+
 	/* Register ib dev */
 	rc = bnxt_re_register_ib(rdev);
 	if (rc) {
 		pr_err("Failed to register with IB: %#x\n", rc);
 		goto fail;
 	}
+	set_bit(BNXT_RE_FLAG_IBDEV_REGISTERED, &rdev->flags);
 	dev_info(rdev_to_dev(rdev), "Device registered successfully");
 	for (i = 0; i < ARRAY_SIZE(bnxt_re_attributes); i++) {
 		rc = device_create_file(&rdev->ibdev.dev,
@@ -1395,7 +1372,6 @@ static int bnxt_re_ib_reg(struct bnxt_re_dev *rdev)
 			goto fail;
 		}
 	}
-	set_bit(BNXT_RE_FLAG_IBDEV_REGISTERED, &rdev->flags);
 	ib_get_eth_speed(&rdev->ibdev, 1, &rdev->active_speed,
 			 &rdev->active_width);
 	set_bit(BNXT_RE_FLAG_ISSUE_ROCE_STATS, &rdev->flags);
@@ -1404,17 +1380,21 @@ static int bnxt_re_ib_reg(struct bnxt_re_dev *rdev)
 
 	return 0;
 free_sctx:
-	bnxt_re_net_stats_ctx_free(rdev, rdev->qplib_ctx.stats.fw_id, true);
+	bnxt_re_net_stats_ctx_free(rdev, rdev->qplib_ctx.stats.fw_id);
 free_ctx:
 	bnxt_qplib_free_ctx(rdev->en_dev->pdev, &rdev->qplib_ctx);
 disable_rcfw:
 	bnxt_qplib_disable_rcfw_channel(&rdev->rcfw);
 free_ring:
-	bnxt_re_net_ring_free(rdev, rdev->rcfw.creq_ring_id, true);
+	bnxt_re_net_ring_free(rdev, rdev->rcfw.creq_ring_id);
 free_rcfw:
 	bnxt_qplib_free_rcfw_channel(&rdev->rcfw);
 fail:
-	bnxt_re_ib_unreg(rdev, true);
+	if (!locked)
+		rtnl_lock();
+	bnxt_re_ib_unreg(rdev);
+	rtnl_unlock();
+
 	return rc;
 }
 
@@ -1567,7 +1547,7 @@ static int bnxt_re_netdev_event(struct notifier_block *notifier,
 		 */
 		if (atomic_read(&rdev->sched_count) > 0)
 			goto exit;
-		bnxt_re_ib_unreg(rdev, false);
+		bnxt_re_ib_unreg(rdev);
 		bnxt_re_remove_one(rdev);
 		bnxt_re_dev_unreg(rdev);
 		break;
@@ -1646,7 +1626,10 @@ static void __exit bnxt_re_mod_exit(void)
 		 */
 		flush_workqueue(bnxt_re_wq);
 		bnxt_re_dev_stop(rdev);
-		bnxt_re_ib_unreg(rdev, true);
+		/* Acquire the rtnl_lock as the L2 resources are freed here */
+		rtnl_lock();
+		bnxt_re_ib_unreg(rdev);
+		rtnl_unlock();
 		bnxt_re_remove_one(rdev);
 		bnxt_re_dev_unreg(rdev);
 	}