diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2021-11-26 19:15:29 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-11-29 15:12:36 +0300 |
| commit | fd888e85fe6b661e78044dddfec0be5271afa626 (patch) | |
| tree | c1ef71d45fd053e110de5aeea2b0eb02b1e2c681 /net/core/rtnetlink.c | |
| parent | 07b8ca3792dec6bc3288b08ff85d80b5330de1d6 (diff) | |
| download | linux-fd888e85fe6b661e78044dddfec0be5271afa626.tar.xz | |
net: Write lock dev_base_lock without disabling bottom halves.
The writer acquires dev_base_lock with disabled bottom halves.
The reader can acquire dev_base_lock without disabling bottom halves
because there is no writer in softirq context.
On PREEMPT_RT the softirqs are preemptible and local_bh_disable() acts
as a lock to ensure that resources, that are protected by disabling
bottom halves, remain protected.
This leads to a circular locking dependency if the lock acquired with
disabled bottom halves (as in write_lock_bh()) and somewhere else with
enabled bottom halves (as by read_lock() in netstat_show()) followed by
disabling bottom halves (cxgb_get_stats() -> t4_wr_mbox_meat_timeout()
-> spin_lock_bh()). This is the reverse locking order.
All read_lock() invocation are from sysfs callback which are not invoked
from softirq context. Therefore there is no need to disable bottom
halves while acquiring a write lock.
Acquire the write lock of dev_base_lock without disabling bottom halves.
Reported-by: Pei Zhang <pezhang@redhat.com>
Reported-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/rtnetlink.c')
| -rw-r--r-- | net/core/rtnetlink.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 6f25c0a8aebe..d6eba554b137 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -842,9 +842,9 @@ static void set_operstate(struct net_device *dev, unsigned char transition) } if (dev->operstate != operstate) { - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); dev->operstate = operstate; - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); netdev_state_change(dev); } } @@ -2778,11 +2778,11 @@ static int do_setlink(const struct sk_buff *skb, if (tb[IFLA_LINKMODE]) { unsigned char value = nla_get_u8(tb[IFLA_LINKMODE]); - write_lock_bh(&dev_base_lock); + write_lock(&dev_base_lock); if (dev->link_mode ^ value) status |= DO_SETLINK_NOTIFY; dev->link_mode = value; - write_unlock_bh(&dev_base_lock); + write_unlock(&dev_base_lock); } if (tb[IFLA_VFINFO_LIST]) { |