[PATCH 03/13] nptl: Remove clockwait_tid

[Adhemerval Zanella]

It can be replaced with a __futex_abstimed_wait_cancelable64 call,
with the advantage that there is no need to further clock adjustments
to create a absolute timeout.  It allows to remove the now ununsed
futex_timed_wait_cancel64 internal function.

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 nptl/pthread_join_common.c    | 70 ++++++-----------------------------
 sysdeps/nptl/futex-internal.h | 49 ------------------------
 2 files changed, 12 insertions(+), 107 deletions(-)

diff --git a/nptl/pthread_join_common.c b/nptl/pthread_join_common.c
index 67d8e2b780..8a95c58ff3 100644
--- a/nptl/pthread_join_common.c
+++ b/nptl/pthread_join_common.c
@@ -32,55 +32,6 @@ cleanup (void *arg)
   atomic_compare_exchange_weak_acquire (&arg, &self, NULL);
 }
 
-/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
-   wake-up when the clone terminates.  The memory location contains the
-   thread ID while the clone is running and is reset to zero by the kernel
-   afterwards.  The kernel up to version 3.16.3 does not use the private futex
-   operations for futex wake-up when the clone terminates.  */
-static int
-clockwait_tid (pid_t *tidp, clockid_t clockid,
-               const struct __timespec64 *abstime)
-{
-  pid_t tid;
-  int ret;
-
-  if (! valid_nanoseconds (abstime->tv_nsec))
-    return EINVAL;
-
-  /* Repeat until thread terminated.  */
-  while ((tid = *tidp) != 0)
-    {
-      struct __timespec64 rt;
-
-      /* Get the current time. This can only fail if clockid is
-         invalid. */
-      if (__glibc_unlikely (__clock_gettime64 (clockid, &rt)))
-        return EINVAL;
-
-      /* Compute relative timeout.  */
-      rt.tv_sec = abstime->tv_sec - rt.tv_sec;
-      rt.tv_nsec = abstime->tv_nsec - rt.tv_nsec;
-      if (rt.tv_nsec < 0)
-        {
-          rt.tv_nsec += 1000000000;
-          --rt.tv_sec;
-        }
-
-      /* Already timed out?  */
-      if (rt.tv_sec < 0)
-        return ETIMEDOUT;
-
-      /* If *tidp == tid, wait until thread terminates or the wait times out.
-         The kernel up to version 3.16.3 does not use the private futex
-         operations for futex wake-up when the clone terminates.  */
-      ret = futex_timed_wait_cancel64 (tidp, tid, &rt, LLL_SHARED);
-      if (ret == -ETIMEDOUT || ret == -EOVERFLOW)
-        return -ret;
-    }
-
-  return 0;
-}
-
 int
 __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
                         clockid_t clockid,
@@ -137,15 +88,18 @@ __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
 	 un-wait-ed for again.  */
       pthread_cleanup_push (cleanup, &pd->joinid);
 
-      if (abstime != NULL)
-	result = clockwait_tid (&pd->tid, clockid, abstime);
-      else
-	{
-	  pid_t tid;
-	  /* We need acquire MO here so that we synchronize with the
-	     kernel's store to 0 when the clone terminates. (see above)  */
-	  while ((tid = atomic_load_acquire (&pd->tid)) != 0)
-	    lll_futex_wait_cancel (&pd->tid, tid, LLL_SHARED);
+     /* We need acquire MO here so that we synchronize with the
+        kernel's store to 0 when the clone terminates. (see above)  */
+      pid_t tid;
+      while ((tid = atomic_load_acquire (&pd->tid)) != 0)
+        {
+	  int ret = __futex_abstimed_wait_cancelable64 (
+	    (unsigned int *) &pd->tid, tid, clockid, abstime, LLL_SHARED);
+	  if (ret == ETIMEDOUT || ret == EOVERFLOW)
+	    {
+	      result = ret;
+	      break;
+	    }
 	}
 
       pthread_cleanup_pop (0);
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
index 96d1318091..d5f13d15fb 100644
--- a/sysdeps/nptl/futex-internal.h
+++ b/sysdeps/nptl/futex-internal.h
@@ -390,55 +390,6 @@ futex_unlock_pi (unsigned int *futex_word, int private)
     }
 }
 
-static __always_inline int
-futex_timed_wait_cancel64 (pid_t *tidp,  pid_t tid,
-                           const struct __timespec64 *timeout, int private)
-{
-  int err = INTERNAL_SYSCALL_CANCEL (futex_time64, tidp,
-                                     __lll_private_flag (FUTEX_WAIT, private),
-                                     tid, timeout);
-#ifndef __ASSUME_TIME64_SYSCALLS
-  if (err == -ENOSYS)
-    {
-      if (in_time_t_range (timeout->tv_sec))
-        {
-          struct timespec ts32 = valid_timespec64_to_timespec (*timeout);
-
-          err = INTERNAL_SYSCALL_CANCEL (futex, tidp,
-                                         __lll_private_flag (FUTEX_WAIT,
-                                                             private),
-                                         tid, &ts32);
-        }
-      else
-        err = -EOVERFLOW;
-    }
-#endif
-  switch (err)
-    {
-    case 0:
-    case -EAGAIN:
-    case -EINTR:
-    case -ETIMEDOUT:
-    case -EDEADLK:
-    case -ENOSYS:
-    case -EOVERFLOW:  /* Passed absolute timeout uses 64 bit time_t type, but
-                         underlying kernel does not support 64 bit time_t futex
-                         syscalls.  */
-    case -EPERM:  /*  The caller is not allowed to attach itself to the futex.
-		      Used to check if PI futexes are supported by the
-		      kernel.  */
-      return -err;
-
-    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 -EFAULT: /* Must have been caused by a glibc or application bug.  */
-    /* No other errors are documented at this time.  */
-    default:
-      futex_fatal_error ();
-    }
-}
-
 /* The futex_abstimed_wait_cancelable64 has been moved to a separate file
    to avoid problems with exhausting available registers on some architectures
    - e.g. on m68k architecture.  */
-- 
2.25.1