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authorParav Pandit <parav@mellanox.com>2018-11-16 03:50:57 +0200
committerJason Gunthorpe <jgg@mellanox.com>2018-11-22 12:39:26 -0700
commit01b671170d7f82b959dad6d5dbb44d7a915e647d (patch)
tree4d63f4aee9785f4f39cf42b8c39ce98b9e22f720 /drivers/infiniband/core/core_priv.h
parentRDMA/cma: Move cma module specific functions to cma_priv.h (diff)
downloadlinux-dev-01b671170d7f82b959dad6d5dbb44d7a915e647d.tar.xz
linux-dev-01b671170d7f82b959dad6d5dbb44d7a915e647d.zip
RDMA/core: Sync unregistration with netlink commands
When the rdma device is getting removed, get resource info can race with device removal, as below: CPU-0 CPU-1 -------- -------- rdma_nl_rcv_msg() nldev_res_get_cq_dumpit() mutex_lock(device_lock); get device reference mutex_unlock(device_lock); [..] ib_unregister_device() /* Valid reference to * device->dev exists. */ ib_dealloc_device() [..] provider->fill_res_entry(); Even though device object is not freed, fill_res_entry() can get called on device which doesn't have a driver anymore. Kernel core device reference count is not sufficient, as this only keeps the structure valid, and doesn't guarantee the driver is still loaded. Similar race can occur with device renaming and device removal, where device_rename() tries to rename a unregistered device. While this is fine for devices of a class which are not net namespace aware, but it is incorrect for net namespace aware class coming in subsequent series. If a class is net namespace aware, then the below [1] call trace is observed in above situation. Therefore, to avoid the race, keep a reference count and let device unregistration wait until all netlink users drop the reference. [1] Call trace: kernfs: ns required in 'infiniband' for 'mlx5_0' WARNING: CPU: 18 PID: 44270 at fs/kernfs/dir.c:842 kernfs_find_ns+0x104/0x120 libahci i2c_core mlxfw libata dca [last unloaded: devlink] RIP: 0010:kernfs_find_ns+0x104/0x120 Call Trace: kernfs_find_and_get_ns+0x2e/0x50 sysfs_rename_link_ns+0x40/0xb0 device_rename+0xb2/0xf0 ib_device_rename+0xb3/0x100 [ib_core] nldev_set_doit+0x165/0x190 [ib_core] rdma_nl_rcv_msg+0x249/0x250 [ib_core] ? netlink_deliver_tap+0x8f/0x3e0 rdma_nl_rcv+0xd6/0x120 [ib_core] netlink_unicast+0x17c/0x230 netlink_sendmsg+0x2f0/0x3e0 sock_sendmsg+0x30/0x40 __sys_sendto+0xdc/0x160 Fixes: da5c85078215 ("RDMA/nldev: add driver-specific resource tracking") Signed-off-by: Parav Pandit <parav@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'drivers/infiniband/core/core_priv.h')
-rw-r--r--drivers/infiniband/core/core_priv.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h
index 1b2575430032..cc7535c5e192 100644
--- a/drivers/infiniband/core/core_priv.h
+++ b/drivers/infiniband/core/core_priv.h
@@ -267,6 +267,7 @@ static inline int ib_mad_enforce_security(struct ib_mad_agent_private *map,
#endif
struct ib_device *ib_device_get_by_index(u32 ifindex);
+void ib_device_put(struct ib_device *device);
/* RDMA device netlink */
void nldev_init(void);
void nldev_exit(void);