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, 4 deletions

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 71a56193e6..d10f4ea800 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -31,6 +31,7 @@
 #include <kernel-features.h>
 #include <exit-thread.h>
 #include <default-sched.h>
+#include <futex-internal.h>
 
 #include <shlib-compat.h>
 
@@ -269,7 +270,7 @@ START_THREAD_DEFN
 
   /* Allow setxid from now onwards.  */
   if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
-    lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
+    futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
 
 #ifdef __NR_set_robust_list
 # ifndef __ASSUME_SET_ROBUST_LIST
@@ -414,7 +415,8 @@ START_THREAD_DEFN
 	  this->__list.__next = NULL;
 
 	  atomic_or (&this->__lock, FUTEX_OWNER_DIED);
-	  lll_futex_wake (&this->__lock, 1, /* XYZ */ LLL_SHARED);
+	  futex_wake ((unsigned int *) &this->__lock, 1,
+		      /* XYZ */ FUTEX_SHARED);
 	}
       while (robust != (void *) &pd->robust_head);
     }
@@ -442,7 +444,11 @@ START_THREAD_DEFN
       /* Some other thread might call any of the setXid functions and expect
 	 us to reply.  In this case wait until we did that.  */
       do
-	lll_futex_wait (&pd->setxid_futex, 0, LLL_PRIVATE);
+	/* XXX This differs from the typical futex_wait_simple pattern in that
+	   the futex_wait condition (setxid_futex) is different from the
+	   condition used in the surrounding loop (cancelhandling).  We need
+	   to check and document why this is correct.  */
+	futex_wait_simple (&pd->setxid_futex, 0, FUTEX_PRIVATE);
       while (pd->cancelhandling & SETXID_BITMASK);
 
       /* Reset the value so that the stack can be reused.  */
@@ -683,7 +689,7 @@ __pthread_create_2_1 (newthread, attr, start_routine, arg)
 	     stillborn thread.  */
 	  if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0)
 				== -2))
-	    lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
+	    futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
 
 	  /* Free the resources.  */
 	  __deallocate_stack (pd);