1. 27 6月, 2013 1 次提交
    • N
      net: fix kernel deadlock with interface rename and netdev name retrieval. · 5dbe7c17
      Nicolas Schichan 提交于
      When the kernel (compiled with CONFIG_PREEMPT=n) is performing the
      rename of a network interface, it can end up waiting for a workqueue
      to complete. If userland is able to invoke a SIOCGIFNAME ioctl or a
      SO_BINDTODEVICE getsockopt in between, the kernel will deadlock due to
      the fact that read_secklock_begin() will spin forever waiting for the
      writer process (the one doing the interface rename) to update the
      devnet_rename_seq sequence.
      
      This patch fixes the problem by adding a helper (netdev_get_name())
      and using it in the code handling the SIOCGIFNAME ioctl and
      SO_BINDTODEVICE setsockopt.
      
      The netdev_get_name() helper uses raw_seqcount_begin() to avoid
      spinning forever, waiting for devnet_rename_seq->sequence to become
      even. cond_resched() is used in the contended case, before retrying
      the access to give the writer process a chance to finish.
      
      The use of raw_seqcount_begin() will incur some unneeded work in the
      reader process in the contended case, but this is better than
      deadlocking the system.
      Signed-off-by: NNicolas Schichan <nschichan@freebox.fr>
      Acked-by: NEric Dumazet <edumazet@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5dbe7c17
  2. 26 6月, 2013 8 次提交
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