From cf7ad3030271c55a7119a8c2162563e3f6e93879 Mon Sep 17 00:00:00 2001 From: Parav Pandit Date: Fri, 21 Dec 2018 16:19:24 +0200 Subject: [PATCH] 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: 0f29b46d49b0 ("IB/mad: add new ioctl to ABI to support new registration options") Signed-off-by: Parav Pandit Reviewed-by: Jack Morgenstein Reviewed-by: Ira Weiny Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/user_mad.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 52ebb1711d14..0204a4fefd13 100644 --- a/drivers/infiniband/core/user_mad.c +++ b/drivers/infiniband/core/user_mad.c @@ -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); }