linux-toradex.git/net/can/af_can.c, branch v5.4-rc1

can: af_can: use spin_lock_bh() for &net->can.rcvlists_lock

2019-09-04T11:29:15+00:00

The can_rx_unregister() can be called from NAPI (soft IRQ) context, at least
by j1939 stack. This leads to potential dead lock with &net->can.rcvlists_lock
called from can_rx_register:
===============================================================================
 WARNING: inconsistent lock state
 4.19.0-20181029-1-g3e67f95ba0d3 #3 Not tainted
 --------------------------------
 inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
 testj1939/224 [HC0[0]:SC1[1]:HE1:SE0] takes:
 1ad0fda3 (&(&net->can.rcvlists_lock)->rlock){+.?.}, at: can_rx_unregister+0x4c/0x1ac
 {SOFTIRQ-ON-W} state was registered at:
   lock_acquire+0xd0/0x1f4
   _raw_spin_lock+0x30/0x40
   can_rx_register+0x5c/0x14c
   j1939_netdev_start+0xdc/0x1f8
   j1939_sk_bind+0x18c/0x1c8
   __sys_bind+0x70/0xb0
   sys_bind+0x10/0x14
   ret_fast_syscall+0x0/0x28
   0xbedc9b64
 irq event stamp: 2440
 hardirqs last  enabled at (2440): [] __local_bh_enable_ip+0xac/0x184
 hardirqs last disabled at (2439): [] __local_bh_enable_ip+0x60/0x184
 softirqs last  enabled at (2412): [] release_sock+0x84/0xa4
 softirqs last disabled at (2415): [] irq_exit+0x100/0x1b0

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&(&net->can.rcvlists_lock)->rlock);
   
     lock(&(&net->can.rcvlists_lock)->rlock);

  *** DEADLOCK ***

 2 locks held by testj1939/224:
  #0: 168eb13b (rcu_read_lock){....}, at: netif_receive_skb_internal+0x3c/0x350
  #1: 168eb13b (rcu_read_lock){....}, at: can_receive+0x88/0x1c0
===============================================================================

To avoid this situation, we should use spin_lock_bh() instead of spin_lock().

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: af_can: remove NULL-ptr checks from users of can_dev_rcv_lists_find()

2019-09-04T11:29:15+00:00

Since using the "struct can_ml_priv" for the per device "struct
dev_rcv_lists" the call can_dev_rcv_lists_find() cannot fail anymore.
This patch simplifies af_can by removing the NULL pointer checks from
the dev_rcv_lists returned by can_dev_rcv_lists_find().

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: make use of preallocated can_ml_priv for per device struct can_dev_rcv_lists

2019-09-04T11:29:15+00:00

This patch removes the old method of allocating the per device protocol
specific memory via a netdevice_notifier. This had the drawback, that
the allocation can fail, leading to a lot of null pointer checks in the
code. This also makes the live cycle management of this memory quite
complicated.

This patch switches from the allocating the struct can_dev_rcv_lists in
a NETDEV_REGISTER call to using the dev->ml_priv, which is allocated by
the driver since the previous patch.

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: introduce CAN midlayer private and allocate it automatically

2019-09-04T11:29:14+00:00

This patch introduces the CAN midlayer private structure ("struct
can_ml_priv") which should be used to hold protocol specific per device
data structures. For now it's only member is "struct can_dev_rcv_lists".

The CAN midlayer private is allocated via alloc_netdev()'s private and
assigned to "struct net_device::ml_priv" during device creation. This is
done transparently for CAN drivers using alloc_candev(). The slcan, vcan
and vxcan drivers which are not using alloc_candev() have been adopted
manually. The memory layout of the netdev_priv allocated via
alloc_candev() will looke like this:

  +-------------------------+
  | driver's priv           |
  +-------------------------+
  | struct can_ml_priv      |
  +-------------------------+
  | array of struct sk_buff |
  +-------------------------+

Signed-off-by: Oleksij Rempel 
Signed-off-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: af_can: can_pernet_exit(): no need to iterate over and cleanup registered CAN devices

2019-09-04T11:29:14+00:00

The networking core takes care and unregisters every network device in
a namespace before calling the can_pernet_exit() hook. This patch
removes the unneeded cleanup.

Acked-by: Oliver Hartkopp 
Suggested-by: Kirill Tkhai 
Signed-off-by: Oleksij Rempel 
Signed-off-by: Marc Kleine-Budde

can: af_can: can_rx_register(): use max() instead of open coding it

2019-09-04T11:29:14+00:00

This patch replaces an open coded max by the proper kernel define max().

Acked-by: Oliver Hartkopp 
Signed-off-by: Oleksij Rempel 
Signed-off-by: Marc Kleine-Budde

can: af_can: give variable holding the CAN receiver and the receiver list a sensible name

2019-09-04T11:29:14+00:00

This patch gives the variables holding the CAN receiver and the receiver
list a better name by renaming them from "r to "rcv" and "rl" to
"recv_list".

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: af_can: rename find_dev_rcv_lists() to can_dev_rcv_lists_find()

2019-09-04T11:29:14+00:00

This patch add the commonly used prefix "can_" to the find_dev_rcv_lists()
function and moves the "find" to the end, as the function returns a struct
can_dev_rcv_list. This improves the overall readability of the code.

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: af_can: rename find_rcv_list() to can_rcv_list_find()

2019-09-04T11:29:14+00:00

This patch add the commonly used prefix "can_" to the find_rcv_list()
function and add the "find" to the end, as the function returns a struct
rcv_list. This improves the overall readability of the code.

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde

can: af_can: give variable holding the CAN per device receive lists a sensible name

2019-09-04T11:29:14+00:00

This patch gives the variables holding the CAN receive filter lists a
better name by renaming them from "d" to "dev_rcv_lists".

Signed-off-by: Oleksij Rempel 
Acked-by: Oliver Hartkopp 
Signed-off-by: Marc Kleine-Budde