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authorFeras Daoud <ferasda@mellanox.com>2016-12-28 15:47:23 +0300
committerDoug Ledford <dledford@redhat.com>2017-01-12 22:01:03 +0300
commit0a0007f28304cb9fc87809c86abb80ec71317f20 (patch)
tree9be2c5ba0d6dbd4513623d4d12377474ee58720e /drivers
parent1c3098cdb05207e740715857df7b0998e372f527 (diff)
downloadlinux-0a0007f28304cb9fc87809c86abb80ec71317f20.tar.xz
IB/ipoib: Fix deadlock between rmmod and set_mode
When calling set_mode from sys/fs, the call flow locks the sys/fs lock first and then tries to lock rtnl_lock (when calling ipoib_set_mod). On the other hand, the rmmod call flow takes the rtnl_lock first (when calling unregister_netdev) and then tries to take the sys/fs lock. Deadlock a->b, b->a. The problem starts when ipoib_set_mod frees it's rtnl_lck and tries to get it after that. set_mod: [<ffffffff8104f2bd>] ? check_preempt_curr+0x6d/0x90 [<ffffffff814fee8e>] __mutex_lock_slowpath+0x13e/0x180 [<ffffffff81448655>] ? __rtnl_unlock+0x15/0x20 [<ffffffff814fed2b>] mutex_lock+0x2b/0x50 [<ffffffff81448675>] rtnl_lock+0x15/0x20 [<ffffffffa02ad807>] ipoib_set_mode+0x97/0x160 [ib_ipoib] [<ffffffffa02b5f5b>] set_mode+0x3b/0x80 [ib_ipoib] [<ffffffff8134b840>] dev_attr_store+0x20/0x30 [<ffffffff811f0fe5>] sysfs_write_file+0xe5/0x170 [<ffffffff8117b068>] vfs_write+0xb8/0x1a0 [<ffffffff8117ba81>] sys_write+0x51/0x90 [<ffffffff8100b0f2>] system_call_fastpath+0x16/0x1b rmmod: [<ffffffff81279ffc>] ? put_dec+0x10c/0x110 [<ffffffff8127a2ee>] ? number+0x2ee/0x320 [<ffffffff814fe6a5>] schedule_timeout+0x215/0x2e0 [<ffffffff8127cc04>] ? vsnprintf+0x484/0x5f0 [<ffffffff8127b550>] ? string+0x40/0x100 [<ffffffff814fe323>] wait_for_common+0x123/0x180 [<ffffffff81060250>] ? default_wake_function+0x0/0x20 [<ffffffff8119661e>] ? ifind_fast+0x5e/0xb0 [<ffffffff814fe43d>] wait_for_completion+0x1d/0x20 [<ffffffff811f2e68>] sysfs_addrm_finish+0x228/0x270 [<ffffffff811f2fb3>] sysfs_remove_dir+0xa3/0xf0 [<ffffffff81273f66>] kobject_del+0x16/0x40 [<ffffffff8134cd14>] device_del+0x184/0x1e0 [<ffffffff8144e59b>] netdev_unregister_kobject+0xab/0xc0 [<ffffffff8143c05e>] rollback_registered+0xae/0x130 [<ffffffff8143c102>] unregister_netdevice+0x22/0x70 [<ffffffff8143c16e>] unregister_netdev+0x1e/0x30 [<ffffffffa02a91b0>] ipoib_remove_one+0xe0/0x120 [ib_ipoib] [<ffffffffa01ed95f>] ib_unregister_device+0x4f/0x100 [ib_core] [<ffffffffa021f5e1>] mlx4_ib_remove+0x41/0x180 [mlx4_ib] [<ffffffffa01ab771>] mlx4_remove_device+0x71/0x90 [mlx4_core] Fixes: 862096a8bbf8 ("IB/ipoib: Add more rtnl_link_ops callbacks") Cc: <stable@vger.kernel.org> # v3.6+ Cc: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Feras Daoud <ferasda@mellanox.com> Signed-off-by: Erez Shitrit <erezsh@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib_cm.c12
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib_main.c6
2 files changed, 9 insertions, 9 deletions
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 096c4f6fbd65..1c7a9a16efc7 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -1507,12 +1507,14 @@ static ssize_t set_mode(struct device *d, struct device_attribute *attr,
ret = ipoib_set_mode(dev, buf);
- rtnl_unlock();
-
- if (!ret)
- return count;
+ /* The assumption is that the function ipoib_set_mode returned
+ * with the rtnl held by it, if not the value -EBUSY returned,
+ * then no need to rtnl_unlock
+ */
+ if (ret != -EBUSY)
+ rtnl_unlock();
- return ret;
+ return (!ret || ret == -EBUSY) ? count : ret;
}
static DEVICE_ATTR(mode, S_IWUSR | S_IRUGO, show_mode, set_mode);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index cbd06a882a60..045f844d7f4a 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -492,8 +492,7 @@ int ipoib_set_mode(struct net_device *dev, const char *buf)
priv->tx_wr.wr.send_flags &= ~IB_SEND_IP_CSUM;
ipoib_flush_paths(dev);
- rtnl_lock();
- return 0;
+ return (!rtnl_trylock()) ? -EBUSY : 0;
}
if (!strcmp(buf, "datagram\n")) {
@@ -502,8 +501,7 @@ int ipoib_set_mode(struct net_device *dev, const char *buf)
dev_set_mtu(dev, min(priv->mcast_mtu, dev->mtu));
rtnl_unlock();
ipoib_flush_paths(dev);
- rtnl_lock();
- return 0;
+ return (!rtnl_trylock()) ? -EBUSY : 0;
}
return -EINVAL;