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MXS-1875 Ensure cleanup of DCB does not cause crash.

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- If a client DCB should be moved to some other worker than
  the current one (cli and maxinfo), and that fails, the
  thread id must be reset to that of the calling thread as
  otherwise asserts will be triggered.
- If the creation of the first DCB fails, then the dcb list
  for that thread will be NULL and thus must be accessed
  with some caution.
This commit is contained in:
Johan Wikman 2018-05-22 14:13:54 +03:00
parent 14dc215a78
commit 3097137a2f
1 changed files with 17 additions and 4 deletions
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21
server/core/dcb.cc
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@ -2812,8 +2812,11 @@ static void dcb_remove_from_list(DCB *dcb)
}
else
{
DCB *current = this_unit.all_dcbs[dcb->poll.thread.id]->thread.next;
// If the creation of the DCB failed, it will not have been added
// to the list at all. And if it happened to be the first DCB to be
// created, then `prev` is NULL at this point.
DCB *prev = this_unit.all_dcbs[dcb->poll.thread.id];
DCB *current = prev ? prev->thread.next : NULL;
while (current)
{
@ -3397,7 +3400,14 @@ public:
void execute(Worker& worker)
{
ss_dassert(worker.id() == m_dcb->poll.thread.id);
dcb_add_to_worker(worker.id(), m_dcb, m_events);
bool added = dcb_add_to_worker(worker.id(), m_dcb, m_events);
ss_dassert(added);
if (!added)
{
dcb_close(m_dcb);
}
}
private:
@ -3420,7 +3430,7 @@ static bool dcb_add_to_worker(int worker_id, DCB* dcb, uint32_t events)
// stored on the main thread),
if (dcb->poll.thread.id == Worker::get_current_id())
{
// we'll add it immediatelt to the list,
// we'll add it immediately to the list,
dcb_add_to_list(dcb);
}
else
@ -3552,9 +3562,12 @@ int poll_add_dcb(DCB *dcb)
{
/**
* We failed to add the DCB to a worker. Revert the state so that it
* will be treated as a DCB in the correct state.
* will be treated as a DCB in the correct state. As this will involve
* cleanup, ensure that the current thread is the owner, as otherwise
* debug asserts will be triggered.
*/
dcb->state = old_state;
dcb->poll.thread.id = Worker::get_current_id();
rc = -1;
}