New pthread rwlock that is more scalable.

This replaces the pthread rwlock with a new implementation that uses a
more scalable algorithm (primarily through not using a critical section
anymore to make state changes).  The fast path for rdlock acquisition and
release is now basically a single atomic read-modify write or CAS and a few
branches.  See nptl/pthread_rwlock_common.c for details.

	* nptl/DESIGN-rwlock.txt: Remove.
	* nptl/lowlevelrwlock.sym: Remove.
	* nptl/Makefile: Add new tests.
	* nptl/pthread_rwlock_common.c: New file.  Contains the new rwlock.
	* nptl/pthreadP.h (PTHREAD_RWLOCK_PREFER_READER_P): Remove.
	(PTHREAD_RWLOCK_WRPHASE, PTHREAD_RWLOCK_WRLOCKED,
	PTHREAD_RWLOCK_RWAITING, PTHREAD_RWLOCK_READER_SHIFT,
	PTHREAD_RWLOCK_READER_OVERFLOW, PTHREAD_RWLOCK_WRHANDOVER,
	PTHREAD_RWLOCK_FUTEX_USED): New.
	* nptl/pthread_rwlock_init.c (__pthread_rwlock_init): Adapt to new
	implementation.
	* nptl/pthread_rwlock_rdlock.c (__pthread_rwlock_rdlock_slow): Remove.
	(__pthread_rwlock_rdlock): Adapt.
	* nptl/pthread_rwlock_timedrdlock.c
	(pthread_rwlock_timedrdlock): Adapt.
	* nptl/pthread_rwlock_timedwrlock.c
	(pthread_rwlock_timedwrlock): Adapt.
	* nptl/pthread_rwlock_trywrlock.c (pthread_rwlock_trywrlock): Adapt.
	* nptl/pthread_rwlock_tryrdlock.c (pthread_rwlock_tryrdlock): Adapt.
	* nptl/pthread_rwlock_unlock.c (pthread_rwlock_unlock): Adapt.
	* nptl/pthread_rwlock_wrlock.c (__pthread_rwlock_wrlock_slow): Remove.
	(__pthread_rwlock_wrlock): Adapt.
	* nptl/tst-rwlock10.c: Adapt.
	* nptl/tst-rwlock11.c: Adapt.
	* nptl/tst-rwlock17.c: New file.
	* nptl/tst-rwlock18.c: New file.
	* nptl/tst-rwlock19.c: New file.
	* nptl/tst-rwlock2b.c: New file.
	* nptl/tst-rwlock8.c: Adapt.
	* nptl/tst-rwlock9.c: Adapt.
	* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/hppa/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/sparc/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h
	(pthread_rwlock_t): Adapt.
	* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
	(pthread_rwlock_t): Adapt.
	* sysdeps/x86/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
	* nptl/nptl-printers.py (): Adapt.
	* nptl/nptl_lock_constants.pysym: Adapt.
	* nptl/test-rwlock-printers.py: Adapt.
	* nptl/test-rwlockattr-printers.c: Adapt.
	* nptl/test-rwlockattr-printers.py: Adapt.

1 files changed, 5 insertions, 101 deletions

diff --git a/nptl/pthread_rwlock_wrlock.c b/nptl/pthread_rwlock_wrlock.c
index 461ffdc06c..335fcd18cc 100644
--- a/nptl/pthread_rwlock_wrlock.c
+++ b/nptl/pthread_rwlock_wrlock.c
@@ -16,114 +16,18 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <sysdep.h>
-#include <lowlevellock.h>
-#include <futex-internal.h>
-#include <pthread.h>
-#include <pthreadP.h>
-#include <stap-probe.h>
-#include <elide.h>
-
-
-/* Acquire write lock for RWLOCK.  */
-static int __attribute__((noinline))
-__pthread_rwlock_wrlock_slow (pthread_rwlock_t *rwlock)
-{
-  int result = 0;
-  int futex_shared =
-      rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
-
-  /* Caller has taken the lock.  */
-
-  while (1)
-    {
-      /* Make sure we are not holding the rwlock as a writer.  This is
-	 a deadlock situation we recognize and report.  */
-      if (__builtin_expect (rwlock->__data.__writer
-			    == THREAD_GETMEM (THREAD_SELF, tid), 0))
-	{
-	  result = EDEADLK;
-	  break;
-	}
-
-      /* Remember that we are a writer.  */
-      if (++rwlock->__data.__nr_writers_queued == 0)
-	{
-	  /* Overflow on number of queued writers.  */
-	  --rwlock->__data.__nr_writers_queued;
-	  result = EAGAIN;
-	  break;
-	}
-
-      int waitval = rwlock->__data.__writer_wakeup;
-
-      /* Free the lock.  */
-      lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
-
-      /* Wait for the writer or reader(s) to finish.  We do not check the
-	 return value because we decide how to continue based on the state of
-	 the rwlock.  */
-      futex_wait_simple (&rwlock->__data.__writer_wakeup, waitval,
-			 futex_shared);
-
-      /* Get the lock.  */
-      lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
-
-      /* To start over again, remove the thread from the writer list.  */
-      --rwlock->__data.__nr_writers_queued;
-
-      /* Get the rwlock if there is no writer and no reader.  */
-      if (rwlock->__data.__writer == 0 && rwlock->__data.__nr_readers == 0)
-	{
-	  /* Mark self as writer.  */
-	  rwlock->__data.__writer = THREAD_GETMEM (THREAD_SELF, tid);
-
-	  LIBC_PROBE (wrlock_acquire_write, 1, rwlock);
-	  break;
-	}
-    }
-
-  /* We are done, free the lock.  */
-  lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
-
-  return result;
-}
-
-/* Fast path of acquiring write lock for RWLOCK.  */
+#include "pthread_rwlock_common.c"
 
+/* See pthread_rwlock_common.c.  */
 int
 __pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
 {
   LIBC_PROBE (wrlock_entry, 1, rwlock);
 
-  if (ELIDE_LOCK (rwlock->__data.__rwelision,
-		  rwlock->__data.__lock == 0
-		  && rwlock->__data.__writer == 0
-		  && rwlock->__data.__nr_readers == 0))
-    return 0;
-
-  /* Make sure we are alone.  */
-  lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
-
-  /* Get the rwlock if there is no writer and no reader.  */
-  if (__glibc_likely((rwlock->__data.__writer |
-	rwlock->__data.__nr_readers) == 0))
-    {
-      /* Mark self as writer.  */
-      rwlock->__data.__writer = THREAD_GETMEM (THREAD_SELF, tid);
-
-      LIBC_PROBE (wrlock_acquire_write, 1, rwlock);
-
-      /* We are done, free the lock.  */
-      lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
-
-      return 0;
-    }
-
-  return __pthread_rwlock_wrlock_slow (rwlock);
+  int result = __pthread_rwlock_wrlock_full (rwlock, NULL);
+  LIBC_PROBE (wrlock_acquire_write, 1, rwlock);
+  return result;
 }
 
-
 weak_alias (__pthread_rwlock_wrlock, pthread_rwlock_wrlock)
 hidden_def (__pthread_rwlock_wrlock)