[PATCH rdma-rc] RDMA/mlx5: Fix crash when unbind multiport slave

[Leon Romanovsky <leon@kernel.org>]

From: Maor Gottlieb <maorg@nvidia.com>

Fix the below crash when delete slave from the unaffiliated list
twice. First time when the slave is bounded to the master and the
second when the slave is unloaded.

Fix it by checking if slave is unaffiliated (doesn't have ib device)
before removing from the list.

[ 5140.584361] RIP: 0010:mlx5r_mp_remove+0x4e/0xa0 [mlx5_ib]
[ 5140.595866] Call Trace:
[ 5140.596213]  auxiliary_bus_remove+0x18/0x30
[ 5140.596738]  __device_release_driver+0x177/x220
[ 5140.597304]  device_release_driver+0x24/0x30
[ 5140.597832]  bus_remove_device+0xd8/0x140
[ 5140.598339]  device_del+0x18a/0x3e0
[ 5140.598795]  mlx5_rescan_drivers_locked+0xa9/0x210 [mlx5_core]
[ 5140.599521]  mlx5_unregister_device+0x34/0x60 [mlx5_core]
[ 5140.600184]  mlx5_uninit_one+0x32/0x100 [mlx5_core]
[ 5140.600792]  remove_one+0x6e/0xe0 [mlx5_core]
[ 5140.601350]  pci_device_remove+0x36/0xa0
[ 5140.601846]  __device_release_driver+0x177/0x220
[ 5140.602408]  device_driver_detach+0x3c/0xa0
[ 5140.602931]  unbind_store+0x113/0x130
[ 5140.603400]  kernfs_fop_write_iter+0x110/0x1a0
[ 5140.603942]  new_sync_write+0x116/0x1a0
[ 5140.604428]  vfs_write+0x1ba/0x260
[ 5140.604873]  ksys_write+0x5f/0xe0
[ 5140.605310]  do_syscall_64+0x3d/0x90
[ 5140.605778]  entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 93f8244431ad ("RDMA/mlx5: Convert mlx5_ib to use auxiliary bus")
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/hw/mlx5/main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 094c976b1eed..2507051f7b89 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -4454,7 +4454,8 @@ static void mlx5r_mp_remove(struct auxiliary_device *adev)
 	mutex_lock(&mlx5_ib_multiport_mutex);
 	if (mpi->ibdev)
 		mlx5_ib_unbind_slave_port(mpi->ibdev, mpi);
-	list_del(&mpi->list);
+	else
+		list_del(&mpi->list);
 	mutex_unlock(&mlx5_ib_multiport_mutex);
 	kfree(mpi);
 }
-- 
2.31.1