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Diffstat (limited to 'winsup/cygwin/DevNotes')
| -rw-r--r-- | winsup/cygwin/DevNotes | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/winsup/cygwin/DevNotes b/winsup/cygwin/DevNotes index 04abd99cc..01293bc50 100644 --- a/winsup/cygwin/DevNotes +++ b/winsup/cygwin/DevNotes @@ -1,3 +1,32 @@ +2012-12-28 cgf-000019 + +(I forgot to mention that cgf-000018 was reverted. Although I never saw +a hang from this, I couldn't convince myself that one wasn't possible.) + +This fix attempts to correct a deadlock where, when a true Windows +signal arrives, Windows creates a thread which "does stuff" and attempts +to exit. In the process of exiting Cygwin grabs the process lock. If +the signal thread has seen the signal and wants to exit, it can't +because the newly-created thread now holds it. But, since the new +thread is relying on the signal thread to release its process lock, +it exits and the process lock is never released. + +To fix this, I removed calls to _cygtls::signal_exit in favor of +flagging that we were exiting by setting signal_exit_code (almost forgot +to mark that NO_COPY: that would have been fun). The new function +setup_signal_exit() now handles setting things up so that ReadFile loop +in wait_sig will do the right thing when it terminates. This function +may just Sleep indefinitely if a signal is being sent from a thread +other than the signal thread. wait_sig() was changed so that it will +essentially drop into asychronous-read-mode when a signal which exits +has been detected. The ReadFile loop is exited when we know that the +process is supposed to be exiting and there is nothing else in the +signal queue. + +Although I never actually saw this happen, exit_thread() was also +changed to release the process lock and just sleep indefintely if it is +detected that we are exiting. + 2012-12-21 cgf-000018 Re: cgf-000017 |