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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Selvin Xavier <selvin.xavier@broadcom.com>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 073/142] RDMA/bnxt_re: Fix system hang when registration with L2 driver fails
Date:   Fri, 14 Dec 2018 12:59:18 +0100
Message-Id: <20181214115749.982029974@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 3c4b1419c33c2417836a63f8126834ee36968321 ]

Driver doesn't release rtnl lock if registration with
L2 driver (bnxt_re_register_netdev) fais and this causes
hang while requesting for the next lock.

[  371.635416] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  371.635417] kworker/u48:1   D    0   634      2 0x80000000
[  371.635423] Workqueue: bnxt_re bnxt_re_task [bnxt_re]
[  371.635424] Call Trace:
[  371.635426]  ? __schedule+0x36b/0xbd0
[  371.635429]  schedule+0x39/0x90
[  371.635430]  schedule_preempt_disabled+0x11/0x20
[  371.635431]  __mutex_lock+0x45b/0x9c0
[  371.635433]  ? __mutex_lock+0x16d/0x9c0
[  371.635435]  ? bnxt_re_ib_reg+0x2b/0xb30 [bnxt_re]
[  371.635438]  ? wake_up_klogd+0x37/0x40
[  371.635442]  bnxt_re_ib_reg+0x2b/0xb30 [bnxt_re]
[  371.635447]  bnxt_re_task+0xfd/0x180 [bnxt_re]
[  371.635449]  process_one_work+0x216/0x5b0
[  371.635450]  ? process_one_work+0x189/0x5b0
[  371.635453]  worker_thread+0x4e/0x3d0
[  371.635455]  kthread+0x10e/0x140
[  371.635456]  ? process_one_work+0x5b0/0x5b0
[  371.635458]  ? kthread_stop+0x220/0x220
[  371.635460]  ret_from_fork+0x3a/0x50
[  371.635477] INFO: task NetworkManager:1228 blocked for more than 120 seconds.
[  371.635478]       Tainted: G    B      OE     4.20.0-rc1+ #42
[  371.635479] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

Release the rtnl_lock correctly in the failure path.

Fixes: de5c95d0f518 ("RDMA/bnxt_re: Fix system crash during RDMA resource initialization")
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/infiniband/hw/bnxt_re/main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/infiniband/hw/bnxt_re/main.c b/drivers/infiniband/hw/bnxt_re/main.c
index 85cd1a3593d6..bb3f16273938 100644
--- a/drivers/infiniband/hw/bnxt_re/main.c
+++ b/drivers/infiniband/hw/bnxt_re/main.c
@@ -1252,6 +1252,7 @@ static int bnxt_re_ib_reg(struct bnxt_re_dev *rdev)
 	/* Registered a new RoCE device instance to netdev */
 	rc = bnxt_re_register_netdev(rdev);
 	if (rc) {
+		rtnl_unlock();
 		pr_err("Failed to register with netedev: %#x\n", rc);
 		return -EINVAL;
 	}
-- 
2.19.1