perhaps a simpler workaround: https://bazaar.launchpad.net/~vapier/libnih/libnih/revision/1056?start_revid=1056
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to libnih in Ubuntu. https://bugs.launchpad.net/bugs/518921 Title: unprotected check ... clear race on caught signals count in nih_signal_poll() may cause deadlocks Status in NIH Utility Library: Triaged Status in libnih package in Ubuntu: Invalid Bug description: Ubuntu lucid libnih 1.0.1-1 nih_signal_handler() increments signals_caught[signum] per signal; nih_signal_poll() is responsible for checking and resetting the count. However, a signal can arrive after nih_signal_poll() decides not to run the handler (because signals_caught[signum] is 0) but before the signals_caught counts are reset at the end of the function. (This is the classic atomicity problem when waiting for signals --- see pselect(2) for background.) The signal pipe will have been written, which does ensure that nih_main_loop() is guaranteed to wake up again on the next round, but because signals_caught[signum] remains zero for the affected signal, that instance of the signal will be silently ignored when nih_signal_handler() is next called. This can lead to a deadlock if notification of the signal is required for the program to make progress (such as waiting for SIGCHLD to arrive). The attached patch may serve as a workaround, but it's not been extensively tested. I know of no real-world deadlock caused by this bug, but I spotted it when investigating a separate deadlock issue. This bug was found while investigating the following issue, but is probably not directly related: * https://bugs.launchpad.net/ubuntu/+source/plymouth/+bug/518937 (ply_event_loop_process_pending_events can block, causing mountall to deadlock) To manage notifications about this bug go to: https://bugs.launchpad.net/libnih/+bug/518921/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
