Commit 8c954368 authored by Alex Vesker's avatar Alex Vesker Committed by Greg Kroah-Hartman

IB/ipoib: Fix lockdep issue found on ipoib_ib_dev_heavy_flush

[ Upstream commit 1f80bd6a ]

The locking order of vlan_rwsem (LOCK A) and then rtnl (LOCK B),
contradicts other flows such as ipoib_open possibly causing a deadlock.
To prevent this deadlock heavy flush is called with RTNL locked and
only then tries to acquire vlan_rwsem.
This deadlock is possible only when there are child interfaces.

[  140.941758] ======================================================
[  140.946276] WARNING: possible circular locking dependency detected
[  140.950950] 4.15.0-rc1+ #9 Tainted: G           O
[  140.954797] ------------------------------------------------------
[  140.959424] kworker/u32:1/146 is trying to acquire lock:
[  140.963450]  (rtnl_mutex){+.+.}, at: [<ffffffffc083516a>] __ipoib_ib_dev_flush+0x2da/0x4e0 [ib_ipoib]
[  140.970006]
but task is already holding lock:
[  140.975141]  (&priv->vlan_rwsem){++++}, at: [<ffffffffc0834ee1>] __ipoib_ib_dev_flush+0x51/0x4e0 [ib_ipoib]
[  140.982105]
which lock already depends on the new lock.
[  140.990023]
the existing dependency chain (in reverse order) is:
[  140.998650]
-> #1 (&priv->vlan_rwsem){++++}:
[  141.005276]        down_read+0x4d/0xb0
[  141.009560]        ipoib_open+0xad/0x120 [ib_ipoib]
[  141.014400]        __dev_open+0xcb/0x140
[  141.017919]        __dev_change_flags+0x1a4/0x1e0
[  141.022133]        dev_change_flags+0x23/0x60
[  141.025695]        devinet_ioctl+0x704/0x7d0
[  141.029156]        sock_do_ioctl+0x20/0x50
[  141.032526]        sock_ioctl+0x221/0x300
[  141.036079]        do_vfs_ioctl+0xa6/0x6d0
[  141.039656]        SyS_ioctl+0x74/0x80
[  141.042811]        entry_SYSCALL_64_fastpath+0x1f/0x96
[  141.046891]
-> #0 (rtnl_mutex){+.+.}:
[  141.051701]        lock_acquire+0xd4/0x220
[  141.055212]        __mutex_lock+0x88/0x970
[  141.058631]        __ipoib_ib_dev_flush+0x2da/0x4e0 [ib_ipoib]
[  141.063160]        __ipoib_ib_dev_flush+0x71/0x4e0 [ib_ipoib]
[  141.067648]        process_one_work+0x1f5/0x610
[  141.071429]        worker_thread+0x4a/0x3f0
[  141.074890]        kthread+0x141/0x180
[  141.078085]        ret_from_fork+0x24/0x30
[  141.081559]

other info that might help us debug this:
[  141.088967]  Possible unsafe locking scenario:
[  141.094280]        CPU0                    CPU1
[  141.097953]        ----                    ----
[  141.101640]   lock(&priv->vlan_rwsem);
[  141.104771]                                lock(rtnl_mutex);
[  141.109207]                                lock(&priv->vlan_rwsem);
[  141.114032]   lock(rtnl_mutex);
[  141.116800]
 *** DEADLOCK ***

Fixes: b4b678b0 ("IB/ipoib: Grab rtnl lock on heavy flush when calling ndo_open/stop")
Signed-off-by: default avatarAlex Vesker <valex@mellanox.com>
Signed-off-by: default avatarLeon Romanovsky <leon@kernel.org>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent c750773f
......@@ -1203,13 +1203,10 @@ static void __ipoib_ib_dev_flush(struct ipoib_dev_priv *priv,
ipoib_ib_dev_down(dev);
if (level == IPOIB_FLUSH_HEAVY) {
rtnl_lock();
if (test_bit(IPOIB_FLAG_INITIALIZED, &priv->flags))
ipoib_ib_dev_stop(dev);
result = ipoib_ib_dev_open(dev);
rtnl_unlock();
if (result)
if (ipoib_ib_dev_open(dev))
return;
if (netif_queue_stopped(dev))
......@@ -1249,7 +1246,9 @@ void ipoib_ib_dev_flush_heavy(struct work_struct *work)
struct ipoib_dev_priv *priv =
container_of(work, struct ipoib_dev_priv, flush_heavy);
rtnl_lock();
__ipoib_ib_dev_flush(priv, IPOIB_FLUSH_HEAVY, 0);
rtnl_unlock();
}
void ipoib_ib_dev_cleanup(struct net_device *dev)
......
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