1. 13 Feb, 2020 1 commit
    • Witold Krecicki's avatar
      Make isc_task_pause/isc_task_unpause thread safe. · 70c463a6
      Witold Krecicki authored
      isc_task_pause/unpause were inherently thread-unsafe - a task
      could be paused only once by one thread, if the task was running
      while we paused it it led to races. Fix it by making sure that
      the task will pause if requested to, and by using a 'pause reference
      counter' to count task pause requests - a task will be unpaused
      iff all threads unpause it.
      
      Don't remove from queue when pausing task - we lock the queue lock
      (expensive), while it's unlikely that the task will be running -
      and we'll remove it anyway in dispatcher
      70c463a6
  2. 12 Feb, 2020 16 commits
  3. 11 Feb, 2020 6 commits
    • Stephen Morris's avatar
      Minor README tweaks · bc539d48
      Stephen Morris authored
      bc539d48
    • Witold Krecicki's avatar
      Don't limit the size of uvreq/nmhandle pool artificially. · a1332396
      Witold Krecicki authored
      There was a hard limit set on number of uvreq and nmhandles
      that can be allocated by a pool, but we don't handle a situation
      where we can't get an uvreq. Don't limit the number at all,
      let the OS deal with it.
      a1332396
    • Ondřej Surý's avatar
      Merge branch '1428-possible-data-race-in-rbtdb-happens-occasionally-on-ppc64le' into 'master' · d3843161
      Ondřej Surý authored
      Convert all atomic operations in isc_rwlock to release-acquire memory ordering
      
      Closes #1428
      
      See merge request !2985
      d3843161
    • Ondřej Surý's avatar
      Convert all atomic operations in isc_rwlock to release-acquire memory ordering · b43f5e02
      Ondřej Surý authored
      The memory ordering in the rwlock was all wrong, I am copying excerpts
      from the https://en.cppreference.com/w/c/atomic/memory_order#Relaxed_ordering
      for the convenience of the reader:
      
        Relaxed ordering
      
        Atomic operations tagged memory_order_relaxed are not synchronization
        operations; they do not impose an order among concurrent memory
        accesses. They only guarantee atomicity and modification order
        consistency.
      
        Release-Acquire ordering
      
        If an atomic store in thread A is tagged memory_order_release and an
        atomic load in thread B from the same variable is tagged
        memory_order_acquire, all memory writes (non-atomic and relaxed atomic)
        that happened-before the atomic store from the point of view of thread
        A, become visible side-effects in thread B. That is, once the atomic
        load is completed, thread B is guaranteed to see everything thread A
        wrote to memory.
      
        The synchronization is established only between the threads releasing
        and acquiring the same atomic variable. Other threads can see different
        order of memory accesses than either or both of the synchronized
        threads.
      
      Which basically means that we had no or weak synchronization between
      threads using the same variables in the rwlock structure.  There should
      not be a significant performance drop because the critical sections were
      already protected by:
      
        while(1) {
          if (relaxed_atomic_operation) {
            break;
          }
          LOCK(lock);
          if (!relaxed_atomic_operation) {
            WAIT(sem, lock);
          }
          UNLOCK(lock)l
        }
      
      I would add one more thing to "Don't do your own crypto, folks.":
      
        - Also don't do your own locking, folks.
      b43f5e02
    • Evan Hunt's avatar
      Merge branch '1598-dnssec-policy-doc' into 'master' · 3116a1c2
      Evan Hunt authored
      Resolve "Improve dnssec-policy documentation"
      
      Closes #1598
      
      See merge request !3023
      3116a1c2
    • Evan Hunt's avatar
      revise dnssec-policy documentation · c7866acb
      Evan Hunt authored
      c7866acb
  4. 10 Feb, 2020 6 commits
  5. 09 Feb, 2020 2 commits
  6. 08 Feb, 2020 9 commits