Make system call modules a bit more robust:

- If we fail to register the system call during MOD_LOAD, then note that
  so that we don't try to deregister it or invoke the chained event handler
  during the subsequent MOD_UNLOAD event.  Doing the deregister when the
  register failed could result in trashing system call entries.
- Add a SI_SUB_SYSCALLS just before starting up init and use that to
  register syscall modules instead of SI_SUB_DRIVERS.  Registering system
  calls as late as possible increases the chances that any other module
  event handlers or SYSINITs in a module are executed to initialize the
  data in a kld before a syscall dependent on that data is able to be
  invoked.

MFC after:	3 days

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index 0566794..4e4f25e 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -113,7 +113,7 @@ static moduledata_t name##_mod = {                             \
        syscall_module_handler,                                 \
        &name##_syscall_mod                                     \
 };                                                             \
-DECLARE_MODULE(name, name##_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE)
+DECLARE_MODULE(name, name##_mod, SI_SUB_SYSCALLS, SI_ORDER_MIDDLE)
 
 #define SYSCALL_MODULE_HELPER(syscallname)              \
 static int syscallname##_syscall = SYS_##syscallname;   \