Add and use new glibc-internal futex API.

This adds new functions for futex operations, starting with wait,
abstimed_wait, reltimed_wait, wake.  They add documentation and error
checking according to the current draft of the Linux kernel futex manpage.

Waiting with absolute or relative timeouts is split into separate functions.
This allows for removing a few cases of code duplication in pthreads code,
which uses absolute timeouts; also, it allows us to put platform-specific
code to go from an absolute to a relative timeout into the platform-specific
futex abstractions..

Futex operations that can be canceled are also split out into separate
functions suffixed by "_cancelable".

There are separate versions for both Linux and NaCl; while they currently
differ only slightly, my expectation is that the separate versions of
lowlevellock-futex.h will eventually be merged into futex-internal.h
when we get to move the lll_ functions over to the new futex API.

1 files changed, 10 insertions, 17 deletions

diff --git a/nptl/sem_init.c b/nptl/sem_init.c
index 575b661f62..bd1b592420 100644
--- a/nptl/sem_init.c
+++ b/nptl/sem_init.c
@@ -21,22 +21,7 @@
 #include <shlib-compat.h>
 #include "semaphoreP.h"
 #include <kernel-features.h>
-
-/* Returns FUTEX_PRIVATE if pshared is zero and private futexes are supported;
-   returns FUTEX_SHARED otherwise.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline int
-futex_private_if_supported (int pshared)
-{
-  if (pshared != 0)
-    return LLL_SHARED;
-#ifdef __ASSUME_PRIVATE_FUTEX
-  return LLL_PRIVATE;
-#else
-  return THREAD_GETMEM (THREAD_SELF, header.private_futex)
-      ^ FUTEX_PRIVATE_FLAG;
-#endif
-}
+#include <futex-internal.h>
 
 
 int
@@ -48,6 +33,13 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
       __set_errno (EINVAL);
       return -1;
     }
+  pshared = pshared != 0 ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
+  int err = futex_supports_pshared (pshared);
+  if (err != 0)
+    {
+      __set_errno (err);
+      return -1;
+    }
 
   /* Map to the internal type.  */
   struct new_sem *isem = (struct new_sem *) sem;
@@ -60,7 +52,8 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
   isem->nwaiters = 0;
 #endif
 
-  isem->private = futex_private_if_supported (pshared);
+  isem->private = (pshared == PTHREAD_PROCESS_PRIVATE
+		   ? FUTEX_PRIVATE : FUTEX_SHARED);
 
   return 0;
 }