Support requeueing for condvars using PI mutex. x86-64 only.

Add support for the new FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI
options of futex.

nptl/ChangeLog

@@ -1,5 +1,14 @@
 2009-07-19  Ulrich Drepper  <drepper@redhat.com>
 
+	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Define
+	FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI.
+	* sysdeps/unix/sysv/linux/x86_64/pthread_cond_broadcast.S: If mutex
+	is a PI mutex, then use FUTEX_CMP_REQUEUE_PI.
+	* sysdeps/unix/sysv/linux/x86_64/pthread_cond_signal.S: Likewise.
+	* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: If mutex
+	is a PI mutex, then use FUTEX_WAIT_REQUEUE_PI.
+	* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: Likewise.
+
 	* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S
 	(__pthread_cond_timedwait): Make more robust.
 

nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h

@@ -54,6 +54,8 @@
 #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
 

nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_broadcast.S

@@ -1,4 +1,4 @@
-/* Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007
+/* Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2009
    Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@@ -70,12 +70,14 @@ __pthread_cond_broadcast:
 8:	cmpq	$-1, %r8
 	je	9f
 
-	/* XXX: The kernel so far doesn't support requeue to PI futex.  */
-	/* XXX: The kernel only supports FUTEX_CMP_REQUEUE to the same
-	   type of futex (private resp. shared).  */
-	testl	$(PI_BIT | PS_BIT), MUTEX_KIND(%r8)
+	/* Do not use requeue for pshared condvars.  */
+	testl	$PS_BIT, MUTEX_KIND(%r8)
 	jne	9f
 
+	/* Requeue to a PI mutex if the PI bit is set.  */
+	testl	$PI_BIT, MUTEX_KIND(%r8)
+	jne	81f
+
 	/* Wake up all threads.  */
 #ifdef __ASSUME_PRIVATE_FUTEX
 	movl	$(FUTEX_CMP_REQUEUE|FUTEX_PRIVATE_FLAG), %esi
@@ -97,6 +99,20 @@ __pthread_cond_broadcast:
 10:	xorl	%eax, %eax
 	retq
 
+	/* Wake up all threads.  */
+81:	movl	$(FUTEX_CMP_REQUEUE_PI|FUTEX_PRIVATE_FLAG), %esi
+	movl	$SYS_futex, %eax
+	movl	$1, %edx
+	movl	$0x7fffffff, %r10d
+	syscall
+
+	/* For any kind of error, which mainly is EAGAIN, we try again
+	   with WAKE.  The general test also covers running on old
+	   kernels.  */
+	cmpq	$-4095, %rax
+	jb	10b
+	jmp	9f
+
 	.align	16
 	/* Unlock.  */
 4:	LOCK

nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_signal.S

@@ -1,4 +1,4 @@
-/* Copyright (C) 2002, 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
+/* Copyright (C) 2002-2005, 2007, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -21,6 +21,7 @@
 #include <shlib-compat.h>
 #include <lowlevellock.h>
 #include <lowlevelcond.h>
+#include <pthread-pi-defines.h>
 #include <kernel-features.h>
 #include <pthread-errnos.h>
 
@@ -56,19 +57,23 @@ __pthread_cond_signal:
 
 	/* Wake up one thread.  */
 	cmpq	$-1, dep_mutex(%r8)
+	movl	$FUTEX_WAKE_OP, %esi
 	movl	$1, %edx
+	movl	$SYS_futex, %eax
+	je	8f
+
+	/* Get the address of the mutex used.  */
+	movq    dep_mutex(%r8), %rcx
+	testl	$PI_BIT, MUTEX_KIND(%rcx)
+	jne	9f
+
 #ifdef __ASSUME_PRIVATE_FUTEX
-	movl	$FUTEX_WAKE_OP, %eax
 	movl	$(FUTEX_WAKE_OP|FUTEX_PRIVATE_FLAG), %esi
-	cmove	%eax, %esi
 #else
-	movl	$0, %eax
-	movl	%fs:PRIVATE_FUTEX, %esi
-	cmove	%eax, %esi
-	orl	$FUTEX_WAKE_OP, %esi
+	orl	%fs:PRIVATE_FUTEX, %esi
 #endif
-	movl	$1, %r10d
-	movl	$SYS_futex, %eax
+
+8:	movl	$1, %r10d
 #if cond_lock != 0
 	addq	$cond_lock, %r8
 #endif
@@ -85,9 +90,27 @@ __pthread_cond_signal:
 	xorl	%eax, %eax
 	retq
 
-7:	/* %esi should be either FUTEX_WAKE_OP or
-	   FUTEX_WAKE_OP|FUTEX_PRIVATE_FLAG from the previous syscall.  */
-	xorl	$(FUTEX_WAKE ^ FUTEX_WAKE_OP), %esi
+	/* Wake up one thread and requeue none in the PI Mutex case.  */
+9:	movl	$(FUTEX_CMP_REQUEUE_PI|FUTEX_PRIVATE_FLAG), %esi
+	movq	%rcx, %r8
+	xorq	%r10, %r10
+	movl	(%rdi), %r9d	// XXX Can this be right?
+	syscall
+
+	leaq	-cond_futex(%rdi), %r8
+
+	/* For any kind of error, we try again with WAKE.
+	   The general test also covers running on old kernels.  */
+	cmpq	$-4095, %rax
+	jb	4f
+
+7:
+#ifdef __ASSUME_PRIVATE_FUTEX
+	andl	$FUTEX_PRIVATE_FLAG, %esi
+#else
+	andl	%fs:PRIVATE_FUTEX, %esi
+#endif
+	orl	$FUTEX_WAKE, %esi
 	movl	$SYS_futex, %eax
 	/* %rdx should be 1 already from $FUTEX_WAKE_OP syscall.
 	movl	$1, %edx  */

nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S

@@ -21,6 +21,7 @@
 #include <shlib-compat.h>
 #include <lowlevellock.h>
 #include <lowlevelcond.h>
+#include <pthread-pi-defines.h>
 #include <pthread-errnos.h>
 
 #include <kernel-features.h>
@@ -58,6 +59,9 @@ __pthread_cond_timedwait:
 	pushq	%r14
 	cfi_adjust_cfa_offset(8)
 	cfi_rel_offset(%r14, 0)
+	pushq	%r15
+	cfi_adjust_cfa_offset(8)
+	cfi_rel_offset(%r15, 0)
 #ifdef __ASSUME_FUTEX_CLOCK_REALTIME
 # define FRAME_SIZE 32
 #else
@@ -160,9 +164,41 @@ __pthread_cond_timedwait:
 	movl	$FUTEX_WAIT_BITSET, %eax
 	movl	$(FUTEX_WAIT_BITSET|FUTEX_PRIVATE_FLAG), %esi
 	cmove	%eax, %esi
+	je	60f
+
+	movq	dep_mutex(%rdi), %r8
+	/* Requeue to a PI mutex if the PI bit is set.  */
+	testl	$PI_BIT, MUTEX_KIND(%r8)
+	je	60f
+
+	movl	$(FUTEX_WAIT_REQUEUE_PI|FUTEX_PRIVATE_FLAG), %esi
+	xorl	%eax, %eax
 	/* The following only works like this because we only support
 	   two clocks, represented using a single bit.  */
+	testl	$1, cond_nwaiters(%rdi)
+	movl	$FUTEX_CLOCK_REALTIME, %edx
+	cmove	%edx, %eax
+	orl	%eax, %esi
+	movq	%r12, %rdx
+	addq	$cond_futex, %rdi
+	movl	$SYS_futex, %eax
+	syscall
+
+	movl	$1, %r15d
+#ifdef __ASSUME_REQUEUE_PI
+	jmp	62f
+#else
+	cmpq	$-4095, %rax
+	jnae	62f
+
+	movl	$(FUTEX_WAIT_BITSET|FUTEX_PRIVATE_FLAG), %esi
+	subq	$cond_futex, %rdi
+#endif
+
+60:	xorl	%r15d, %r15d
 	xorl	%eax, %eax
+	/* The following only works like this because we only support
+	   two clocks, represented using a single bit.  */
 	testl	$1, cond_nwaiters(%rdi)
 	movl	$FUTEX_CLOCK_REALTIME, %edx
 	movl	$0xffffffff, %r9d
@@ -172,7 +208,7 @@ __pthread_cond_timedwait:
 	addq	$cond_futex, %rdi
 	movl	$SYS_futex, %eax
 	syscall
-	movq	%rax, %r14
+62:	movq	%rax, %r14
 
 	movl	(%rsp), %edi
 	callq	__pthread_disable_asynccancel
@@ -253,14 +289,23 @@ __pthread_cond_timedwait:
 #endif
 	jne	40f
 
-41:	movq	16(%rsp), %rdi
+	/* If requeue_pi is used the kernel performs the locking of the
+	   mutex. */
+41:	xorl	%eax, %eax
+	testl	%r15d, %r15d
+	jnz	63f
+
+	movq	16(%rsp), %rdi
 	callq	__pthread_mutex_cond_lock
 
-	testq	%rax, %rax
+63:	testq	%rax, %rax
 	cmoveq	%r14, %rax
 
 48:	addq	$FRAME_SIZE, %rsp
 	cfi_adjust_cfa_offset(-FRAME_SIZE)
+	popq	%r15
+	cfi_adjust_cfa_offset(-8)
+	cfi_restore(%r15)
 	popq	%r14
 	cfi_adjust_cfa_offset(-8)
 	cfi_restore(%r14)
@@ -274,10 +319,11 @@ __pthread_cond_timedwait:
 	retq
 
 	/* Initial locking failed.  */
-31:	cfi_adjust_cfa_offset(3 * 8 + FRAME_SIZE)
-	cfi_rel_offset(%r12, FRAME_SIZE + 16)
-	cfi_rel_offset(%r13, FRAME_SIZE + 8)
-	cfi_rel_offset(%r14, FRAME_SIZE)
+31:	cfi_adjust_cfa_offset(4 * 8 + FRAME_SIZE)
+	cfi_rel_offset(%r12, FRAME_SIZE + 24)
+	cfi_rel_offset(%r13, FRAME_SIZE + 16)
+	cfi_rel_offset(%r14, FRAME_SIZE + 8)
+	cfi_rel_offset(%r15, FRAME_SIZE)
 #if cond_lock != 0
 	addq	$cond_lock, %rdi
 #endif
@@ -353,6 +399,8 @@ __pthread_cond_timedwait:
 
 #ifndef __ASSUME_FUTEX_CLOCK_REALTIME
 .Lreltmo:
+	xorl	%r15d, %r15d
+
 	/* Get internal lock.  */
 	movl	$1, %esi
 	xorl	%eax, %eax
@@ -716,9 +764,10 @@ __condvar_cleanup2:
 	callq	__pthread_mutex_cond_lock
 
 	movq	24(%rsp), %rdi
-	movq	FRAME_SIZE(%rsp), %r14
-	movq	FRAME_SIZE+8(%rsp), %r13
-	movq	FRAME_SIZE+16(%rsp), %r12
+	movq	FRAME_SIZE(%rsp), %r15
+	movq	FRAME_SIZE+8(%rsp), %r14
+	movq	FRAME_SIZE+16(%rsp), %r13
+	movq	FRAME_SIZE+24(%rsp), %r12
 .LcallUR:
 	call	_Unwind_Resume@PLT
 	hlt