We are not allowed to block on the RCU reader side, so can't
just hold the mutex as before. As a quick fix, convert it to
a spinlock.
Fixes: d9f1f61c0801 ("tap: Extending tap device create/destroy APIs")
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct rcu_head rcu;
dev_t major;
struct idr minor_idr;
struct rcu_head rcu;
dev_t major;
struct idr minor_idr;
- struct mutex minor_lock;
const char *device_name;
struct list_head next;
};
const char *device_name;
struct list_head next;
};
- mutex_lock(&tap_major->minor_lock);
- retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_KERNEL);
+ spin_lock(&tap_major->minor_lock);
+ retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
if (retval >= 0) {
tap->minor = retval;
} else if (retval == -ENOSPC) {
netdev_err(tap->dev, "Too many tap devices\n");
retval = -EINVAL;
}
if (retval >= 0) {
tap->minor = retval;
} else if (retval == -ENOSPC) {
netdev_err(tap->dev, "Too many tap devices\n");
retval = -EINVAL;
}
- mutex_unlock(&tap_major->minor_lock);
+ spin_unlock(&tap_major->minor_lock);
unlock:
rcu_read_unlock();
unlock:
rcu_read_unlock();
- mutex_lock(&tap_major->minor_lock);
+ spin_lock(&tap_major->minor_lock);
if (tap->minor) {
idr_remove(&tap_major->minor_idr, tap->minor);
tap->minor = 0;
}
if (tap->minor) {
idr_remove(&tap_major->minor_idr, tap->minor);
tap->minor = 0;
}
- mutex_unlock(&tap_major->minor_lock);
+ spin_unlock(&tap_major->minor_lock);
unlock:
rcu_read_unlock();
unlock:
rcu_read_unlock();
- mutex_lock(&tap_major->minor_lock);
+ spin_lock(&tap_major->minor_lock);
tap = idr_find(&tap_major->minor_idr, minor);
if (tap) {
dev = tap->dev;
dev_hold(dev);
}
tap = idr_find(&tap_major->minor_idr, minor);
if (tap) {
dev = tap->dev;
dev_hold(dev);
}
- mutex_unlock(&tap_major->minor_lock);
+ spin_unlock(&tap_major->minor_lock);
unlock:
rcu_read_unlock();
unlock:
rcu_read_unlock();
tap_major->major = MAJOR(major);
idr_init(&tap_major->minor_idr);
tap_major->major = MAJOR(major);
idr_init(&tap_major->minor_idr);
- mutex_init(&tap_major->minor_lock);
+ spin_lock_init(&tap_major->minor_lock);
tap_major->device_name = device_name;
tap_major->device_name = device_name;