IB/usnic: Fix potential deadlock

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[ Upstream commit 8036e90f92 ]

Acquiring the rtnl lock while holding usdev_lock could result in a
deadlock.

For example:

usnic_ib_query_port()
| mutex_lock(&us_ibdev->usdev_lock)
 | ib_get_eth_speed()
  | rtnl_lock()

rtnl_lock()
| usnic_ib_netdevice_event()
 | mutex_lock(&us_ibdev->usdev_lock)

This commit moves the usdev_lock acquisition after the rtnl lock has been
released.

This is safe to do because usdev_lock is not protecting anything being
accessed in ib_get_eth_speed(). Hence, the correct order of holding locks
(rtnl -> usdev_lock) is not violated.

Signed-off-by: Parvi Kaustubhi <pkaustub@cisco.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Parvi Kaustubhi 2018-12-11 14:15:42 -08:00 • committed by Greg Kroah-Hartman

parent 2250c4b400

commit c0ce3a4076

1 changed files with 7 additions and 4 deletions

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drivers/infiniband/hw/usnic/usnic_ib_verbs.c

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