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.

sysdeps/sparc/nptl/pthread_barrier_init.c

@@ -35,10 +35,9 @@ __pthread_barrier_init (barrier, attr, count)
   struct pthread_barrierattr *iattr = (struct pthread_barrierattr *) attr;
   if (iattr != NULL)
     {
-      if (iattr->pshared != PTHREAD_PROCESS_PRIVATE
-	  && __builtin_expect (iattr->pshared != PTHREAD_PROCESS_SHARED, 0))
-	/* Invalid attribute.  */
-	return EINVAL;
+      int err = futex_supports_pshared (iattr->pshared);
+      if (err != 0)
+	return err;
     }
 
   ibarrier = (union sparc_pthread_barrier *) barrier;

sysdeps/sparc/nptl/pthread_barrier_wait.c

@@ -21,6 +21,7 @@
 #include <lowlevellock.h>
 #include <pthreadP.h>
 #include <sparc-nptl.h>
+#include <futex-internal.h>
 
 /* Wait on barrier.  */
 int
@@ -31,6 +32,7 @@ __pthread_barrier_wait (barrier)
     = (union sparc_pthread_barrier *) barrier;
   int result = 0;
   int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
+  int futex_private = ibarrier->s.pshared ? FUTEX_SHARED : FUTEX_PRIVATE;
 
   /* Make sure we are alone.  */
   lll_lock (ibarrier->b.lock, private);
@@ -46,7 +48,7 @@ __pthread_barrier_wait (barrier)
       ++ibarrier->b.curr_event;
 
       /* Wake up everybody.  */
-      lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
+      futex_wake (&ibarrier->b.curr_event, INT_MAX, futex_private);
 
       /* This is the thread which finished the serialization.  */
       result = PTHREAD_BARRIER_SERIAL_THREAD;
@@ -62,7 +64,7 @@ __pthread_barrier_wait (barrier)
 
       /* Wait for the event counter of the barrier to change.  */
       do
-	lll_futex_wait (&ibarrier->b.curr_event, event, private);
+	futex_wait_simple (&ibarrier->b.curr_event, event, futex_private);
       while (event == ibarrier->b.curr_event);
     }
 

sysdeps/sparc/sparc32/pthread_barrier_wait.c

@@ -21,6 +21,7 @@
 #include <lowlevellock.h>
 #include <pthreadP.h>
 #include <sparc-nptl.h>
+#include <futex-internal.h>
 
 /* Wait on barrier.  */
 int
@@ -31,6 +32,7 @@ __pthread_barrier_wait (barrier)
     = (union sparc_pthread_barrier *) barrier;
   int result = 0;
   int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
+  int futex_private = ibarrier->s.pshared ? FUTEX_SHARED : FUTEX_PRIVATE;
 
   /* Make sure we are alone.  */
   lll_lock (ibarrier->b.lock, private);
@@ -46,7 +48,7 @@ __pthread_barrier_wait (barrier)
       ++ibarrier->b.curr_event;
 
       /* Wake up everybody.  */
-      lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
+      futex_wake (&ibarrier->b.curr_event, INT_MAX, futex_private);
 
       /* This is the thread which finished the serialization.  */
       result = PTHREAD_BARRIER_SERIAL_THREAD;
@@ -62,7 +64,7 @@ __pthread_barrier_wait (barrier)
 
       /* Wait for the event counter of the barrier to change.  */
       do
-	lll_futex_wait (&ibarrier->b.curr_event, event, private);
+	futex_wait_simple (&ibarrier->b.curr_event, event, futex_private);
       while (event == ibarrier->b.curr_event);
     }
 

sysdeps/sparc/sparc32/sem_init.c

@@ -20,23 +20,7 @@
 #include <semaphore.h>
 #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
@@ -49,6 +33,14 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
       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;
 
@@ -57,7 +49,8 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
   isem->pad = 0;
   isem->nwaiters = 0;
 
-  isem->private = futex_private_if_supported (pshared);
+  isem->private = (pshared == PTHREAD_PROCESS_PRIVATE
+		   ? FUTEX_PRIVATE : FUTEX_SHARED);
 
   return 0;
 }

sysdeps/sparc/sparc32/sem_open.c

@@ -199,7 +199,7 @@ sem_open (const char *name, int oflag, ...)
       sem.newsem.nwaiters = 0;
 
       /* This always is a shared semaphore.  */
-      sem.newsem.private = LLL_SHARED;
+      sem.newsem.private = FUTEX_SHARED;
 
       /* Initialize the remaining bytes as well.  */
       memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',

sysdeps/sparc/sparc32/sem_post.c

@@ -23,34 +23,10 @@
 #include <lowlevellock.h>
 #include <internaltypes.h>
 #include <semaphore.h>
+#include <futex-internal.h>
 
 #include <shlib-compat.h>
 
-/* Wrapper for lll_futex_wake, with error checking.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline void
-futex_wake (unsigned int* futex, int processes_to_wake, int private)
-{
-  int res = lll_futex_wake (futex, processes_to_wake, private);
-  /* No error.  Ignore the number of woken processes.  */
-  if (res >= 0)
-    return;
-  switch (res)
-    {
-    case -EFAULT: /* Could have happened due to memory reuse.  */
-    case -EINVAL: /* Could be either due to incorrect alignment (a bug in
-		     glibc or in the application) or due to memory being
-		     reused for a PI futex.  We cannot distinguish between the
-		     two causes, and one of them is correct use, so we do not
-		     act in this case.  */
-      return;
-    case -ENOSYS: /* Must have been caused by a glibc bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      abort ();
-    }
-}
-
 
 /* See sem_wait for an explanation of the algorithm.  */
 int

sysdeps/sparc/sparc32/sem_wait.c

@@ -17,6 +17,7 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <lowlevellock.h>	/* lll_futex* used by the old code.  */
 #include "sem_waitcommon.c"
 
 int

sysdeps/sparc/sparc32/sem_waitcommon.c

@@ -19,7 +19,7 @@
 
 #include <errno.h>
 #include <sysdep.h>
-#include <lowlevellock.h>
+#include <futex-internal.h>
 #include <internaltypes.h>
 #include <semaphore.h>
 #include <sys/time.h>
@@ -28,104 +28,6 @@
 #include <shlib-compat.h>
 #include <atomic.h>
 
-/* Wrapper for lll_futex_wait with absolute timeout and error checking.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline int
-futex_abstimed_wait (unsigned int* futex, unsigned int expected,
-		     const struct timespec* abstime, int private, bool cancel)
-{
-  int err, oldtype;
-  if (abstime == NULL)
-    {
-      if (cancel)
-	oldtype = __pthread_enable_asynccancel ();
-      err = lll_futex_wait (futex, expected, private);
-      if (cancel)
-	__pthread_disable_asynccancel (oldtype);
-    }
-  else
-    {
-      struct timeval tv;
-      struct timespec rt;
-      int sec, nsec;
-
-      /* Get the current time.  */
-      __gettimeofday (&tv, NULL);
-
-      /* Compute relative timeout.  */
-      sec = abstime->tv_sec - tv.tv_sec;
-      nsec = abstime->tv_nsec - tv.tv_usec * 1000;
-      if (nsec < 0)
-        {
-          nsec += 1000000000;
-          --sec;
-        }
-
-      /* Already timed out?  */
-      if (sec < 0)
-        return ETIMEDOUT;
-
-      /* Do wait.  */
-      rt.tv_sec = sec;
-      rt.tv_nsec = nsec;
-      if (cancel)
-	oldtype = __pthread_enable_asynccancel ();
-      err = lll_futex_timed_wait (futex, expected, &rt, private);
-      if (cancel)
-	__pthread_disable_asynccancel (oldtype);
-    }
-  switch (err)
-    {
-    case 0:
-    case -EAGAIN:
-    case -EINTR:
-    case -ETIMEDOUT:
-      return -err;
-
-    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
-    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
-		     being normalized.  Must have been caused by a glibc or
-		     application bug.  */
-    case -ENOSYS: /* Must have been caused by a glibc bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      abort ();
-    }
-}
-
-/* Wrapper for lll_futex_wake, with error checking.
-   TODO Remove when cleaning up the futex API throughout glibc.  */
-static __always_inline void
-futex_wake (unsigned int* futex, int processes_to_wake, int private)
-{
-  int res = lll_futex_wake (futex, processes_to_wake, private);
-  /* No error.  Ignore the number of woken processes.  */
-  if (res >= 0)
-    return;
-  switch (res)
-    {
-    case -EFAULT: /* Could have happened due to memory reuse.  */
-    case -EINVAL: /* Could be either due to incorrect alignment (a bug in
-		     glibc or in the application) or due to memory being
-		     reused for a PI futex.  We cannot distinguish between the
-		     two causes, and one of them is correct use, so we do not
-		     act in this case.  */
-      return;
-    case -ENOSYS: /* Must have been caused by a glibc bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      abort ();
-    }
-}
-
-
-/* Set this to true if you assume that, in contrast to current Linux futex
-   documentation, lll_futex_wake can return -EINTR only if interrupted by a
-   signal, not spuriously due to some other reason.
-   TODO Discuss EINTR conditions with the Linux kernel community.  For
-   now, we set this to true to not change behavior of semaphores compared
-   to previous glibc builds.  */
-static const int sem_assume_only_signals_cause_futex_EINTR = 1;
 
 static void
 __sem_wait_32_finish (struct new_sem *sem);
@@ -149,8 +51,8 @@ do_futex_wait (struct new_sem *sem, const struct timespec *abstime)
 {
   int err;
 
-  err = futex_abstimed_wait (&sem->value, SEM_NWAITERS_MASK, abstime,
-			     sem->private, true);
+  err = futex_abstimed_wait_cancelable (&sem->value, SEM_NWAITERS_MASK,
+					abstime, sem->private);
 
   return err;
 }
@@ -202,8 +104,7 @@ __new_sem_wait_slow (struct new_sem *sem, const struct timespec *abstime)
 	  __sparc32_atomic_do_unlock24(&sem->pad);
 
 	  err = do_futex_wait(sem, abstime);
-	  if (err == ETIMEDOUT ||
-	      (err == EINTR && sem_assume_only_signals_cause_futex_EINTR))
+	  if (err == ETIMEDOUT || err == EINTR)
 	    {
 	      __set_errno (err);
 	      err = -1;