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IB/umad: Avoid destroying device while it is accessed 

ib_umad_reg_agent2() and ib_umad_reg_agent() access the device name in
dev_notice(), while concurrently, ib_umad_kill_port() can destroy the
device using device_destroy().

        cpu-0                               cpu-1
        -----                               -----
    ib_umad_ioctl()
        [...]                            ib_umad_kill_port()
                                              device_destroy(dev)

        ib_umad_reg_agent()
            dev_notice(dev)

Therefore, first mark ib_dev as NULL, to block any further access in file
ops, unregister the mad agent and destroy the device at the end after
mutex is unlocked.

This ensures that device doesn't get destroyed, while it may get accessed.

Fixes: 0f29b46d49 ("IB/mad: add new ioctl to ABI to support new registration options")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Jack Morgenstein <jackm@mellanox.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
hifive-unleashed-5.1
Parav Pandit 2018-12-21 16:19:24 +02:00 committed by Jason Gunthorpe
parent 900d07c12d
commit cf7ad30302
1 changed files with 13 additions and 9 deletions
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22
drivers/infiniband/core/user_mad.c
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@ -1244,17 +1244,11 @@ static void ib_umad_kill_port(struct ib_umad_port *port)
struct ib_umad_file *file;
int id;
dev_set_drvdata(port->dev, NULL);
dev_set_drvdata(port->sm_dev, NULL);
device_destroy(&umad_class, port->cdev.dev);
device_destroy(&umad_class, port->sm_cdev.dev);
cdev_del(&port->cdev);
cdev_del(&port->sm_cdev);
mutex_lock(&port->file_mutex);
/* Mark ib_dev NULL and block ioctl or other file ops to progress
* further.
*/
port->ib_dev = NULL;
list_for_each_entry(file, &port->file_list, port_list) {
@ -1268,6 +1262,16 @@ static void ib_umad_kill_port(struct ib_umad_port *port)
}
mutex_unlock(&port->file_mutex);
dev_set_drvdata(port->dev, NULL);
dev_set_drvdata(port->sm_dev, NULL);
device_destroy(&umad_class, port->cdev.dev);
device_destroy(&umad_class, port->sm_cdev.dev);
cdev_del(&port->cdev);
cdev_del(&port->sm_cdev);
ida_free(&umad_ida, port->dev_num);
}