1. 30 Apr, 2017 5 commits
    • Arnd Bergmann's avatar
      tty: nozomi: avoid a harmless gcc warning · 58f80ccf
      Arnd Bergmann authored
      commit a4f642a8 upstream.
      
      The nozomi wireless data driver has its own helper function to
      transfer data from a FIFO, doing an extra byte swap on big-endian
      architectures, presumably to bring the data back into byte-serial
      order after readw() or readl() perform their implicit byteswap.
      
      This helper function is used in the receive_data() function to
      first read the length into a 32-bit variable, which causes
      a compile-time warning:
      
      drivers/tty/nozomi.c: In function 'receive_data':
      drivers/tty/nozomi.c:857:9: warning: 'size' may be used uninitialized in this function [-Wmaybe-uninitialized]
      
      The problem is that gcc is unsure whether the data was actually
      read or not. We know that it is at this point, so we can replace
      it with a single readl() to shut up that warning.
      
      I am leaving the byteswap in there, to preserve the existing
      behavior, even though this seems fishy: Reading the length of
      the data into a cpu-endian variable should normally not use
      a second byteswap on big-endian systems, unless the hardware
      is aware of the CPU endianess.
      
      There appears to be a lot more confusion about endianess in this
      driver, so it probably has not worked on big-endian systems in
      a long time, if ever, and I have no way to test it. It's well
      possible that this driver has not been used by anyone in a while,
      the last patch that looks like it was tested on the hardware is
      from 2008.
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      58f80ccf
    • Jon Paul Maloy's avatar
      tipc: correct error in node fsm · 2847736f
      Jon Paul Maloy authored
      commit c4282ca7 upstream.
      
      commit 88e8ac70 ("tipc: reduce transmission rate of reset messages
      when link is down") revealed a flaw in the node FSM, as defined in
      the log of commit 66996b6c ("tipc: extend node FSM").
      
      We see the following scenario:
      1: Node B receives a RESET message from node A before its link endpoint
         is fully up, i.e., the node FSM is in state SELF_UP_PEER_COMING. This
         event will not change the node FSM state, but the (distinct) link FSM
         will move to state RESETTING.
      2: As an effect of the previous event, the local endpoint on B will
         declare node A lost, and post the event SELF_DOWN to the its node
         FSM. This moves the FSM state to SELF_DOWN_PEER_LEAVING, meaning
         that no messages will be accepted from A until it receives another
         RESET message that confirms that A's endpoint has been reset. This
         is  wasteful, since we know this as a fact already from the first
         received RESET, but worse is that the link instance's FSM has not
         wasted this information, but instead moved on to state ESTABLISHING,
         meaning that it repeatedly sends out ACTIVATE messages to the reset
         peer A.
      3: Node A will receive one of the ACTIVATE messages, move its link FSM
         to state ESTABLISHED, and start repeatedly sending out STATE messages
         to node B.
      4: Node B will consistently drop these messages, since it can only accept
         accept a RESET according to its node FSM.
      5: After four lost STATE messages node A will reset its link and start
         repeatedly sending out RESET messages to B.
      6: Because of the reduced send rate for RESET messages, it is very
         likely that A will receive an ACTIVATE (which is sent out at a much
         higher frequency) before it gets the chance to send a RESET, and A
         may hence quickly move back to state ESTABLISHED and continue sending
         out STATE messages, which will again be dropped by B.
      7: GOTO 5.
      8: After having repeated the cycle 5-7 a number of times, node A will
         by chance get in between with sending a RESET, and the situation is
         resolved.
      
      Unfortunately, we have seen that it may take a substantial amount of
      time before this vicious loop is broken, sometimes in the order of
      minutes.
      
      We correct this by making a small correction to the node FSM: When a
      node in state SELF_UP_PEER_COMING receives a SELF_DOWN event, it now
      moves directly back to state SELF_DOWN_PEER_DOWN, instead of as now
      SELF_DOWN_PEER_LEAVING. This is logically consistent, since we don't
      need to wait for RESET confirmation from of an endpoint that we alread
      know has been reset. It also means that node B in the scenario above
      will not be dropping incoming STATE messages, and the link can come up
      immediately.
      
      Finally, a symmetry comparison reveals that the  FSM has a similar
      error when receiving the event PEER_DOWN in state PEER_UP_SELF_COMING.
      Instead of moving to PERR_DOWN_SELF_LEAVING, it should move directly
      to SELF_DOWN_PEER_DOWN. Although we have never seen any negative effect
      of this logical error, we choose fix this one, too.
      
      The node FSM looks as follows after those changes:
      
                                 +----------------------------------------+
                                 |                           PEER_DOWN_EVT|
                                 |                                        |
        +------------------------+----------------+                       |
        |SELF_DOWN_EVT           |                |                       |
        |                        |                |                       |
        |              +-----------+          +-----------+               |
        |              |NODE_      |          |NODE_      |               |
        |   +----------|FAILINGOVER|<---------|SYNCHING   |-----------+   |
        |   |SELF_     +-----------+ FAILOVER_+-----------+   PEER_   |   |
        |   |DOWN_EVT   |          A BEGIN_EVT  A         |   DOWN_EVT|   |
        |   |           |          |            |         |           |   |
        |   |           |          |            |         |           |   |
        |   |           |FAILOVER_ |FAILOVER_   |SYNCH_   |SYNCH_     |   |
        |   |           |END_EVT   |BEGIN_EVT   |BEGIN_EVT|END_EVT    |   |
        |   |           |          |            |         |           |   |
        |   |           |          |            |         |           |   |
        |   |           |         +--------------+        |           |   |
        |   |           +-------->|   SELF_UP_   |<-------+           |   |
        |   |   +-----------------|   PEER_UP    |----------------+   |   |
        |   |   |SELF_DOWN_EVT    +--------------+   PEER_DOWN_EVT|   |   |
        |   |   |                    A        A                   |   |   |
        |   |   |                    |        |                   |   |   |
        |   |   |         PEER_UP_EVT|        |SELF_UP_EVT        |   |   |
        |   |   |                    |        |                   |   |   |
        V   V   V                    |        |                   V   V   V
      +------------+       +-----------+    +-----------+       +------------+
      |SELF_DOWN_  |       |SELF_UP_   |    |PEER_UP_   |       |PEER_DOWN   |
      |PEER_LEAVING|       |PEER_COMING|    |SELF_COMING|       |SELF_LEAVING|
      +------------+       +-----------+    +-----------+       +------------+
             |               |       A        A       |                |
             |               |       |        |       |                |
             |       SELF_   |       |SELF_   |PEER_  |PEER_           |
             |       DOWN_EVT|       |UP_EVT  |UP_EVT |DOWN_EVT        |
             |               |       |        |       |                |
             |               |       |        |       |                |
             |               |    +--------------+    |                |
             |PEER_DOWN_EVT  +--->|  SELF_DOWN_  |<---+   SELF_DOWN_EVT|
             +------------------->|  PEER_DOWN   |<--------------------+
                                  +--------------+
      Acked-by: default avatarYing Xue <ying.xue@windriver.com>
      Signed-off-by: default avatarJon Maloy <jon.maloy@ericsson.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2847736f
    • Jon Paul Maloy's avatar
      tipc: re-enable compensation for socket receive buffer double counting · 76ca3053
      Jon Paul Maloy authored
      commit 7c8bcfb1 upstream.
      
      In the refactoring commit d570d864 ("tipc: enqueue arrived buffers
      in socket in separate function") we did by accident replace the test
      
      if (sk->sk_backlog.len == 0)
           atomic_set(&tsk->dupl_rcvcnt, 0);
      
      with
      
      if (sk->sk_backlog.len)
           atomic_set(&tsk->dupl_rcvcnt, 0);
      
      This effectively disables the compensation we have for the double
      receive buffer accounting that occurs temporarily when buffers are
      moved from the backlog to the socket receive queue. Until now, this
      has gone unnoticed because of the large receive buffer limits we are
      applying, but becomes indispensable when we reduce this buffer limit
      later in this series.
      
      We now fix this by inverting the mentioned condition.
      Acked-by: default avatarYing Xue <ying.xue@windriver.com>
      Signed-off-by: default avatarJon Maloy <jon.maloy@ericsson.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      76ca3053
    • Erik Hugne's avatar
      tipc: make dist queue pernet · 3f315590
      Erik Hugne authored
      commit 541726ab upstream.
      
      Nametable updates received from the network that cannot be applied
      immediately are placed on a defer queue. This queue is global to the
      TIPC module, which might cause problems when using TIPC in containers.
      To prevent nametable updates from escaping into the wrong namespace,
      we make the queue pernet instead.
      Signed-off-by: default avatarErik Hugne <erik.hugne@gmail.com>
      Signed-off-by: default avatarJon Maloy <jon.maloy@ericsson.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3f315590
    • Richard Alpe's avatar
      tipc: make sure IPv6 header fits in skb headroom · 44b3b7e0
      Richard Alpe authored
      commit 9bd160bf upstream.
      
      Expand headroom further in order to be able to fit the larger IPv6
      header. Prior to this patch this caused a skb under panic for certain
      tipc packets when using IPv6 UDP bearer(s).
      Signed-off-by: default avatarRichard Alpe <richard.alpe@ericsson.com>
      Acked-by: default avatarJon Maloy <jon.maloy@ericsson.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarJon Maloy <jon.maloy@ericsson.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      44b3b7e0
  2. 27 Apr, 2017 28 commits
  3. 21 Apr, 2017 7 commits