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| author | Parvi Kaustubhi <pkaustub@cisco.com> | 2018-12-11 14:15:42 -0800 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@mellanox.com> | 2018-12-19 16:30:16 -0700 |
| commit | 8036e90f92aae2784b855a0007ae2d8154d28b3c (patch) | |
| tree | 9318314659953114da77ef2f3739ef0ff4c7a28b | |
| parent | 50c582de1d39231af31c881a8444333bff6f11a8 (diff) | |
| download | linux-8036e90f92aae2784b855a0007ae2d8154d28b3c.tar.gz linux-8036e90f92aae2784b855a0007ae2d8154d28b3c.tar.bz2 linux-8036e90f92aae2784b855a0007ae2d8154d28b3c.zip | |
IB/usnic: Fix potential deadlock
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>
| -rw-r--r-- | drivers/infiniband/hw/usnic/usnic_ib_verbs.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/infiniband/hw/usnic/usnic_ib_verbs.c b/drivers/infiniband/hw/usnic/usnic_ib_verbs.c index 1b9f69d65111..1d4abef17e38 100644 --- a/drivers/infiniband/hw/usnic/usnic_ib_verbs.c +++ b/drivers/infiniband/hw/usnic/usnic_ib_verbs.c @@ -336,13 +336,16 @@ int usnic_ib_query_port(struct ib_device *ibdev, u8 port, usnic_dbg("\n"); - mutex_lock(&us_ibdev->usdev_lock); if (ib_get_eth_speed(ibdev, port, &props->active_speed, - &props->active_width)) { - mutex_unlock(&us_ibdev->usdev_lock); + &props->active_width)) return -EINVAL; - } + /* + * usdev_lock is acquired after (and not before) ib_get_eth_speed call + * because acquiring rtnl_lock in ib_get_eth_speed, while holding + * usdev_lock could lead to a deadlock. + */ + mutex_lock(&us_ibdev->usdev_lock); /* props being zeroed by the caller, avoid zeroing it here */ props->lid = 0; |