diff options
| -rw-r--r-- | libraries/base/GHC/Event/Control.hs | 7 | ||||
| -rw-r--r-- | rts/posix/Signals.c | 17 |
2 files changed, 22 insertions, 2 deletions
diff --git a/libraries/base/GHC/Event/Control.hs b/libraries/base/GHC/Event/Control.hs index 747a416343..5dcc66e6dc 100644 --- a/libraries/base/GHC/Event/Control.hs +++ b/libraries/base/GHC/Event/Control.hs @@ -68,6 +68,7 @@ data Control = W { , wakeupReadFd :: {-# UNPACK #-} !Fd , wakeupWriteFd :: {-# UNPACK #-} !Fd #endif + , didRegisterWakeupFd :: !Bool } deriving (Show) #if defined(HAVE_EVENTFD) @@ -108,13 +109,19 @@ newControl shouldRegister = allocaArray 2 $ \fds -> do , wakeupReadFd = fromIntegral wake_rd , wakeupWriteFd = fromIntegral wake_wr #endif + , didRegisterWakeupFd = shouldRegister } -- | Close the control structure used by the IO manager thread. +-- N.B. If this Control is the Control whose wakeup file was registered with +-- the RTS, then *BEFORE* the wakeup file is closed, we must call +-- c_setIOManagerWakeupFd (-1), so that the RTS does not try to use the wakeup +-- file after it has been closed. closeControl :: Control -> IO () closeControl w = do _ <- c_close . fromIntegral . controlReadFd $ w _ <- c_close . fromIntegral . controlWriteFd $ w + when (didRegisterWakeupFd w) $ c_setIOManagerWakeupFd (-1) #if defined(HAVE_EVENTFD) _ <- c_close . fromIntegral . controlEventFd $ w #else diff --git a/rts/posix/Signals.c b/rts/posix/Signals.c index 5fbb917cf8..a2fa07f091 100644 --- a/rts/posix/Signals.c +++ b/rts/posix/Signals.c @@ -126,7 +126,7 @@ more_handlers(int sig) } // Here's the pipe into which we will send our signals -static int io_manager_wakeup_fd = -1; +static volatile int io_manager_wakeup_fd = -1; static int timer_manager_control_wr_fd = -1; #define IO_MANAGER_WAKEUP 0xff @@ -161,7 +161,20 @@ ioManagerWakeup (void) StgWord8 byte = (StgWord8)IO_MANAGER_WAKEUP; r = write(io_manager_wakeup_fd, &byte, 1); #endif - if (r == -1) { sysErrorBelch("ioManagerWakeup: write"); } + /* N.B. If the TimerManager is shutting down as we run this + * then there is a possiblity that our first read of + * io_manager_wakeup_fd is non-negative, but before we get to the + * write the file is closed. If this occurs, io_manager_wakeup_fd + * will be written into with -1 (GHC.Event.Control does this prior + * to closing), so checking this allows us to distinguish this case. + * To ensure we observe the correct ordering, we declare the + * io_manager_wakeup_fd as volatile. + * Since this is not an error condition, we do not print the error + * message in this case. + */ + if (r == -1 && io_manager_wakeup_fd >= 0) { + sysErrorBelch("ioManagerWakeup: write"); + } } } |