linux-kernel - [PATCH 5.8 45/99] RDMA/core: Fix ordering of CQ pool destruction

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Date:   Tue, 29 Sep 2020 13:01:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bart Van Assche <bvanassche@....org>,
        Yi Zhang <yi.zhang@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 45/99] RDMA/core: Fix ordering of CQ pool destruction

From: Jason Gunthorpe <jgg@...dia.com>

[ Upstream commit 4aa1615268a8ac2b20096211d3f9ac53874067d7 ]

rxe will hold a refcount on the IB device as long as CQ objects exist,
this causes destruction of a rxe device to hang if the CQ pool has any
cached CQs since they are being destroyed after the refcount must go to
zero.

Treat the CQ pool like a client and create/destroy it before/after all
other clients. No users of CQ pool can exist past a client remove call.

Link: https://lore.kernel.org/r/e8a240aa-9e9b-3dca-062f-9130b787f29b@acm.org
Fixes: c7ff819aefea ("RDMA/core: Introduce shared CQ pool API")
Tested-by: Bart Van Assche <bvanassche@....org>
Tested-by: Yi Zhang <yi.zhang@...hat.com>
Signed-off-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/infiniband/core/device.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index eadba29432dd7..abcfe4dc1284f 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1282,6 +1282,8 @@ static void disable_device(struct ib_device *device)
 		remove_client_context(device, cid);
 	}
 
+	ib_cq_pool_destroy(device);
+
 	/* Pairs with refcount_set in enable_device */
 	ib_device_put(device);
 	wait_for_completion(&device->unreg_completion);
@@ -1325,6 +1327,8 @@ static int enable_device_and_get(struct ib_device *device)
 			goto out;
 	}
 
+	ib_cq_pool_init(device);
+
 	down_read(&clients_rwsem);
 	xa_for_each_marked (&clients, index, client, CLIENT_REGISTERED) {
 		ret = add_client_context(device, client);
@@ -1397,7 +1401,6 @@ int ib_register_device(struct ib_device *device, const char *name)
 		goto dev_cleanup;
 	}
 
-	ib_cq_pool_init(device);
 	ret = enable_device_and_get(device);
 	dev_set_uevent_suppress(&device->dev, false);
 	/* Mark for userspace that device is ready */
@@ -1452,7 +1455,6 @@ static void __ib_unregister_device(struct ib_device *ib_dev)
 		goto out;
 
 	disable_device(ib_dev);
-	ib_cq_pool_destroy(ib_dev);
 
 	/* Expedite removing unregistered pointers from the hash table */
 	free_netdevs(ib_dev);
-- 
2.25.1