[1/9,BZ,16892] Add linux-generic lowlevellock.h
diff mbox

Message ID E10DC0AF-A48B-4EC7-8EA4-0A3D3EF6BDD7@linaro.org
State New
Headers show

Commit Message

Bernard Ogden June 9, 2014, 8:24 p.m. UTC
Add linux-generic lowlevellock.h

Based on tile's implementation, with a few changes:

Use INTERNAL_SYSCALL_ERRNO to guarantee that error codes are
positive, then negate it and return. Only applied to the three
functions that actually inspect the error code beyond
compare-to-zero.

Prefer __glibc_unlikely to __builtin_expect, and
atomic_compare_and_exchange_bool_acq to ..._val_acq where
appropriate.

Regards,

Bernie


2014-06-09  Bernard Ogden  <bernie.ogden@linaro.org>

	[BZ #16892]
	* sysdeps/unix/sysv/linux/lowlevellock.h: New file.

Comments

Chris Metcalf June 10, 2014, 3:23 p.m. UTC | #1
On 6/9/2014 4:24 PM, Bernard Ogden wrote:
> +#define lll_futex_timed_wait(futexp, val, timespec, private) \
> +  ({									      \
> +    INTERNAL_SYSCALL_DECL (__err);					      \
> +    long int __ret;							      \
> +    __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),		      \
> +			      __lll_private_flag (FUTEX_WAIT, private),	      \
> +			      (val), (timespec));			      \
> +    if(INTERNAL_SYSCALL_ERROR_P (__ret, __err))				      \
> +      __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));			      \
> +    __ret;								      \
> +  })

Style note: space after "if".  And might as well use __glibc_unlikely().

Maybe use an abstraction like INLINE_FUTEX_SYSCALL to capture the INTERNAL_SYSCALL pieces, e.g.

#define INLINE_FUTEX_SYSCALL(name, nr, args...) \
   ({                                                                    \
     INTERNAL_SYSCALL_DECL (__err);                                      \
     long int __ret = INTERNAL_SYSCALL (name, err, nr, args);            \
     if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (__ret, __err)))     \
         __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));               \
     __ret;                                                              \
   })

Then you could use that throughout, e.g. lll_futex_timed_wait() is just a #define for INLINE_FUTEX_SYSCALL(futex, 4, (futexp), __lll_private_flag (FUTEX_WAIT, private), (val), (timespec)) and all the rest of the mechanism stays in INLINE_FUTEX_SYSCALL().

Otherwise, not tested, but both his and the tile-specific changes look OK to me.
Richard Henderson June 11, 2014, 6:47 p.m. UTC | #2
Many instances of:

> +    if(INTERNAL_SYSCALL_ERROR_P (__ret, __err))				      \

Missed space after IF.

> +      __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));			      \

Silly extra parenthesis around INTERNAL_SYSCALL_ERRNO.


r~

Patch
diff mbox

diff --git a/sysdeps/unix/sysv/linux/lowlevellock.h b/sysdeps/unix/sysv/linux/lowlevellock.h
new file mode 100644
index 0000000..32f249d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/lowlevellock.h
@@ -0,0 +1,335 @@ 
+/* Copyright (C) 2011-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _LOWLEVELLOCK_H
+#define _LOWLEVELLOCK_H	1
+
+#include <time.h>
+#include <sys/param.h>
+#include <bits/pthreadtypes.h>
+#include <atomic.h>
+#include <sysdep.h>
+#include <kernel-features.h>
+
+
+#define FUTEX_WAIT		0
+#define FUTEX_WAKE		1
+#define FUTEX_REQUEUE		3
+#define FUTEX_CMP_REQUEUE	4
+#define FUTEX_WAKE_OP		5
+#define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE	((4 << 24) | 1)
+#define FUTEX_LOCK_PI		6
+#define FUTEX_UNLOCK_PI		7
+#define FUTEX_TRYLOCK_PI	8
+#define FUTEX_WAIT_BITSET	9
+#define FUTEX_WAKE_BITSET	10
+#define FUTEX_WAIT_REQUEUE_PI	11
+#define FUTEX_CMP_REQUEUE_PI	12
+#define FUTEX_PRIVATE_FLAG	128
+#define FUTEX_CLOCK_REALTIME	256
+
+#define FUTEX_BITSET_MATCH_ANY	0xffffffff
+
+/* Values for 'private' parameter of locking macros.  Yes, the
+   definition seems to be backwards.  But it is not.  The bit will be
+   reversed before passing to the system call.  */
+#define LLL_PRIVATE	0
+#define LLL_SHARED	FUTEX_PRIVATE_FLAG
+
+
+#if !defined NOT_IN_libc || defined IS_IN_rtld
+/* In libc.so or ld.so all futexes are private.  */
+# ifdef __ASSUME_PRIVATE_FUTEX
+#  define __lll_private_flag(fl, private) \
+  ((fl) | FUTEX_PRIVATE_FLAG)
+# else
+#  define __lll_private_flag(fl, private) \
+  ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
+# endif
+#else
+# ifdef __ASSUME_PRIVATE_FUTEX
+#  define __lll_private_flag(fl, private) \
+  (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
+# else
+#  define __lll_private_flag(fl, private) \
+  (__builtin_constant_p (private)					      \
+   ? ((private) == 0							      \
+      ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))	      \
+      : (fl))								      \
+   : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG)				      \
+	      & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
+# endif
+#endif
+
+
+#define lll_futex_wait(futexp, val, private) \
+  lll_futex_timed_wait (futexp, val, NULL, private)
+
+#define lll_futex_timed_wait(futexp, val, timespec, private) \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),		      \
+			      __lll_private_flag (FUTEX_WAIT, private),	      \
+			      (val), (timespec));			      \
+    if(INTERNAL_SYSCALL_ERROR_P (__ret, __err))				      \
+      __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));			      \
+    __ret;								      \
+  })
+
+#define lll_futex_timed_wait_bitset(futexp, val, timespec, clockbit, private) \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+    int __op = FUTEX_WAIT_BITSET | clockbit;				      \
+									      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),		      \
+			      __lll_private_flag (__op, private),	      \
+			      (val), (timespec), NULL /* Unused.  */, 	      \
+			      FUTEX_BITSET_MATCH_ANY);			      \
+    if(INTERNAL_SYSCALL_ERROR_P (__ret, __err))				      \
+      __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));			      \
+    __ret;								      \
+  })
+
+#define lll_futex_wake(futexp, nr, private) \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),		      \
+			      __lll_private_flag (FUTEX_WAKE, private),	      \
+			      (nr), 0);					      \
+    if(INTERNAL_SYSCALL_ERROR_P (__ret, __err))				      \
+      __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));			      \
+    __ret;								      \
+  })
+
+#define lll_robust_dead(futexv, private) \
+  do									      \
+    {									      \
+      int *__futexp = &(futexv);					      \
+      atomic_or (__futexp, FUTEX_OWNER_DIED);				      \
+      lll_futex_wake (__futexp, 1, private);				      \
+    }									      \
+  while (0)
+
+/* Returns non-zero if error happened, zero if success.  */
+#define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),		      \
+			      __lll_private_flag (FUTEX_CMP_REQUEUE, private),\
+			      (nr_wake), (nr_move), (mutex), (val));	      \
+    INTERNAL_SYSCALL_ERROR_P (__ret, __err);				      \
+  })
+
+/* Returns non-zero if error happened, zero if success.  */
+#define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),		      \
+			      __lll_private_flag (FUTEX_WAKE_OP, private),    \
+			      (nr_wake), (nr_wake2), (futexp2),		      \
+			      FUTEX_OP_CLEAR_WAKE_IF_GT_ONE);		      \
+    INTERNAL_SYSCALL_ERROR_P (__ret, __err);				      \
+  })
+
+/* Priority Inheritance support.  */
+#define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
+  lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
+
+#define lll_futex_timed_wait_requeue_pi(futexp, val, timespec, clockbit,      \
+					mutex, private)			      \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+    int __op = FUTEX_WAIT_REQUEUE_PI | clockbit;			      \
+									      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 5, (futexp),		      \
+			      __lll_private_flag (__op, private),	      \
+			      (val), (timespec), mutex); 		      \
+    INTERNAL_SYSCALL_ERROR_P (__ret, __err);				      \
+  })
+
+#define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex, val, priv)  \
+  ({									      \
+    INTERNAL_SYSCALL_DECL (__err);					      \
+    long int __ret;							      \
+									      \
+    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),		      \
+			      __lll_private_flag (FUTEX_CMP_REQUEUE_PI, priv),\
+			      (nr_wake), (nr_move), (mutex), (val));	      \
+    INTERNAL_SYSCALL_ERROR_P (__ret, __err);				      \
+  })
+
+
+static inline int __attribute__ ((always_inline))
+__lll_trylock (int *futex)
+{
+  return atomic_compare_and_exchange_bool_acq (futex, 1, 0);
+}
+#define lll_trylock(lock)	__lll_trylock (&(lock))
+
+
+static inline int __attribute__ ((always_inline))
+__lll_cond_trylock (int *futex)
+{
+  return atomic_compare_and_exchange_bool_acq (futex, 2, 0);
+}
+#define lll_cond_trylock(lock)	__lll_cond_trylock (&(lock))
+
+
+static inline int __attribute__ ((always_inline))
+__lll_robust_trylock (int *futex, int id)
+{
+  return atomic_compare_and_exchange_bool_acq (futex, id, 0);
+}
+#define lll_robust_trylock(lock, id) \
+  __lll_robust_trylock (&(lock), id)
+
+extern void __lll_lock_wait_private (int *futex) attribute_hidden;
+extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
+extern int __lll_robust_lock_wait (int *futex, int private) attribute_hidden;
+
+static inline void __attribute__ ((always_inline))
+__lll_lock (int *futex, int private)
+{
+  if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
+    {
+      if (__builtin_constant_p (private) && private == LLL_PRIVATE)
+	__lll_lock_wait_private (futex);
+      else
+	__lll_lock_wait (futex, private);
+    }
+}
+#define lll_lock(futex, private) __lll_lock (&(futex), private)
+
+
+static inline int __attribute__ ((always_inline))
+__lll_robust_lock (int *futex, int id, int private)
+{
+  int result = 0;
+  if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
+    result = __lll_robust_lock_wait (futex, private);
+  return result;
+}
+#define lll_robust_lock(futex, id, private) \
+  __lll_robust_lock (&(futex), id, private)
+
+
+static inline void __attribute__ ((always_inline))
+__lll_cond_lock (int *futex, int private)
+{
+  if (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0)
+    __lll_lock_wait (futex, private);
+}
+#define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
+
+
+#define lll_robust_cond_lock(futex, id, private) \
+  __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)
+
+
+extern int __lll_timedlock_wait (int *futex, const struct timespec *,
+				 int private) attribute_hidden;
+extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *,
+					int private) attribute_hidden;
+
+static inline int __attribute__ ((always_inline))
+__lll_timedlock (int *futex, const struct timespec *abstime, int private)
+{
+  int result = 0;
+  if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
+    result = __lll_timedlock_wait (futex, abstime, private);
+  return result;
+}
+#define lll_timedlock(futex, abstime, private) \
+  __lll_timedlock (&(futex), abstime, private)
+
+
+static inline int __attribute__ ((always_inline))
+__lll_robust_timedlock (int *futex, const struct timespec *abstime,
+			int id, int private)
+{
+  int result = 0;
+  if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
+    result = __lll_robust_timedlock_wait (futex, abstime, private);
+  return result;
+}
+#define lll_robust_timedlock(futex, abstime, id, private) \
+  __lll_robust_timedlock (&(futex), abstime, id, private)
+
+
+#define __lll_unlock(futex, private) \
+  (void)							\
+    ({ int *__futex = (futex);					\
+       int __oldval = atomic_exchange_rel (__futex, 0);		\
+       if (__glibc_unlikely (__oldval > 1))			\
+	 lll_futex_wake (__futex, 1, private);			\
+    })
+#define lll_unlock(futex, private) __lll_unlock(&(futex), private)
+
+
+#define __lll_robust_unlock(futex, private) \
+  (void)							\
+    ({ int *__futex = (futex);					\
+       int __oldval = atomic_exchange_rel (__futex, 0);		\
+       if (__glibc_unlikely (__oldval & FUTEX_WAITERS))		\
+	 lll_futex_wake (__futex, 1, private);			\
+    })
+#define lll_robust_unlock(futex, private) \
+  __lll_robust_unlock(&(futex), private)
+
+
+#define lll_islocked(futex) \
+  (futex != 0)
+
+/* Initializers for lock.  */
+#define LLL_LOCK_INITIALIZER		(0)
+#define LLL_LOCK_INITIALIZER_LOCKED	(1)
+
+/* The states of a lock are:
+    0  -  untaken
+    1  -  taken by one user
+   >1  -  taken by more users */
+
+/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
+   wakeup when the clone terminates.  The memory location contains the
+   thread ID while the clone is running and is reset to zero
+   afterwards.	*/
+#define lll_wait_tid(tid) \
+  do {							\
+    __typeof (tid) __tid;				\
+    while ((__tid = (tid)) != 0)			\
+      lll_futex_wait (&(tid), __tid, LLL_SHARED);	\
+  } while (0)
+
+extern int __lll_timedwait_tid (int *, const struct timespec *)
+  attribute_hidden;
+
+#define lll_timedwait_tid(tid, abstime) \
+  ({							\
+    int __res = 0;					\
+    if ((tid) != 0)					\
+      __res = __lll_timedwait_tid (&(tid), (abstime));	\
+    __res;						\
+  })
+
+#endif /* lowlevellock.h */