Race-condition fix with free_waiter threads during shutdown.

When we shutdown, the main process locks the mutex, causing
all of the free_waiter functions to pile up on their lock.
Once we unlock in the main process, all of the free_waiters
start working. However the next instruction in the main proces
is to destroy the mutex. The short window is all the free_waiter
threads have to do their cleanup before they attempt to unlock
the mutex - which might have been de-allocated (and set to NULL).
End result can be a seg-fault.

This fix adds a ref-count to the mutex so that during shutdown
we spin and wait until all of the free_waiter functions
have completed and the ref-count is set to zero.

1 files changed, 1 insertions, 0 deletions

diff --git a/multipath/main.c b/multipath/main.c
index 8b38a6e..2f227d1 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -439,6 +439,7 @@ main (int argc, char *argv[])
 		condlog(3, "restart multipath configuration process");
 	
 out:
+
 	sysfs_cleanup();
 	dm_lib_release();
 	dm_lib_exit();