Merged revisions 301946 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

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  r301946 | rmudgett | 2011-01-14 15:09:57 -0600 (Fri, 14 Jan 2011) | 13 lines
  
  Deadlock between dahdi_request() and pri_dchannel() processing an incomming call.
  
  The sig_pri_new_ast_channel() is called with the channel private lock held
  when pri_dchannel() calls it and no channel private lock held when
  dahdi_request() calls it.  The use of pri_grab() in
  sig_pri_new_ast_channel() could leave the channel private lock held when
  it returns if the lock was not held before calling it.
  
  Make sig_pri_new_ast_channel() just lock the PRI span lock instead of
  using pri_grab().  It is safe to do this because dahdi_request() does not
  have the channel private lock and the deadlock potential with the PRI span
  lock is only between pri_dchannel() and other threads.
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@301947 65c4cc65-6c06-0410-ace0-fbb531ad65f3