A new(er) mtx_enter_try().

Ok oga@, "the time is now" deraadt@.

17 files changed, 401 insertions, 18 deletions

diff --git a/sys/arch/alpha/alpha/mutex.c b/sys/arch/alpha/alpha/mutex.c
index 0be19335328..82e98c164d1 100644
--- a/sys/arch/alpha/alpha/mutex.c
+++ b/sys/arch/alpha/alpha/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.3 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.4 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -56,6 +56,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _splraise(mtx->mtx_wantipl);
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/amd64/amd64/mutex.S b/sys/arch/amd64/amd64/mutex.S
index 2a9472021a9..38a381b0aef 100644
--- a/sys/arch/amd64/amd64/mutex.S
+++ b/sys/arch/amd64/amd64/mutex.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.S,v 1.6 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.S,v 1.7 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -84,7 +84,48 @@ ENTRY(mtx_enter)
 	call	_C_LABEL(panic)
 5:	.asciz	"mtx_enter: locking against myself"
 #endif
-	
+
+ENTRY(mtx_enter_try)
+1:	movl	MTX_WANTIPL(%rdi), %eax
+	movq	CPUVAR(SELF), %rcx
+	movl	CPU_INFO_ILEVEL(%rcx), %edx	# oipl = cpl;
+	cmpl	%eax, %edx			# if (cpl < mtx->mtx_wantipl)
+	cmovge	%edx, %eax
+	movl	%eax, CPU_INFO_ILEVEL(%rcx)	#	cpl = mtx->mtx_wantipl;
+	/*
+	 * %edx - the old ipl
+	 * %rcx - curcpu()
+	 */
+	xorq	%rax, %rax
+#ifdef MULTIPROCESSOR
+	lock
+#endif
+	cmpxchgq	%rcx, MTX_OWNER(%rdi)	# test_and_set(mtx->mtx_owner)
+	jne	2f
+	movl	%edx, MTX_OLDIPL(%rdi)
+	movq	$1, %rax
+	ret
+
+	/* We failed to obtain the lock. splx and return 0. */
+2:	pushq	%rdi
+	movl	%edx, %edi
+	call	_C_LABEL(spllower)
+	popq	%rdi
+#ifdef DIAGNOSTIC
+	movq	CPUVAR(SELF), %rcx
+	cmpq	MTX_OWNER(%rdi), %rcx
+	je	3f
+#endif
+	xorq	%rax, %rax
+	ret
+
+#ifdef DIAGNOSTIC
+3:	movq	$4f, %rdi
+	call	_C_LABEL(panic)
+4:	.asciz	"mtx_enter: locking against myself"
+#endif
+
+
 ENTRY(mtx_leave)
 	movq	%rdi, %rax
 	xorq	%rcx, %rcx
diff --git a/sys/arch/arm/s3c2xx0/s3c2xx0_mutex.c b/sys/arch/arm/s3c2xx0/s3c2xx0_mutex.c
index 04c3332a1e5..e186a756ca7 100644
--- a/sys/arch/arm/s3c2xx0/s3c2xx0_mutex.c
+++ b/sys/arch/arm/s3c2xx0/s3c2xx0_mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: s3c2xx0_mutex.c,v 1.1 2008/11/26 14:39:14 drahn Exp $	*/
+/*	$OpenBSD: s3c2xx0_mutex.c,v 1.2 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -58,6 +58,18 @@ mtx_enter(struct mutex *mtx)
 }
 
 void
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _splraise(mtx->mtx_wantipl);
+
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
+void
 mtx_leave(struct mutex *mtx)
 {
 	MUTEX_ASSERT_LOCKED(mtx);
diff --git a/sys/arch/arm/xscale/i80321_mutex.c b/sys/arch/arm/xscale/i80321_mutex.c
index c19da126124..9271d29c5ad 100644
--- a/sys/arch/arm/xscale/i80321_mutex.c
+++ b/sys/arch/arm/xscale/i80321_mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: i80321_mutex.c,v 1.1 2007/05/15 05:26:44 miod Exp $	*/
+/*	$OpenBSD: i80321_mutex.c,v 1.2 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -58,6 +58,18 @@ mtx_enter(struct mutex *mtx)
 }
 
 void
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _splraise(mtx->mtx_wantipl);
+
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
+void
 mtx_leave(struct mutex *mtx)
 {
 	MUTEX_ASSERT_LOCKED(mtx);
diff --git a/sys/arch/arm/xscale/pxa2x0_mutex.c b/sys/arch/arm/xscale/pxa2x0_mutex.c
index 605f9b02b56..6952105a8d6 100644
--- a/sys/arch/arm/xscale/pxa2x0_mutex.c
+++ b/sys/arch/arm/xscale/pxa2x0_mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pxa2x0_mutex.c,v 1.1 2007/05/15 05:26:44 miod Exp $	*/
+/*	$OpenBSD: pxa2x0_mutex.c,v 1.2 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -57,6 +57,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _splraise(mtx->mtx_wantipl);
+
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/hppa/hppa/mutex.c b/sys/arch/hppa/hppa/mutex.c
index 77c6cd782d2..5a5750dd67c 100644
--- a/sys/arch/hppa/hppa/mutex.c
+++ b/sys/arch/hppa/hppa/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.4 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.5 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -56,6 +56,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = splraise(mtx->mtx_wantipl);
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/hppa64/hppa64/mutex.c b/sys/arch/hppa64/hppa64/mutex.c
index 0752b964669..8f9d5ebf9a4 100644
--- a/sys/arch/hppa64/hppa64/mutex.c
+++ b/sys/arch/hppa64/hppa64/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.3 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.4 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -54,6 +54,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = splraise(mtx->mtx_wantipl);
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/i386/i386/mutex.S b/sys/arch/i386/i386/mutex.S
index 9428e5b9e35..b82363e1779 100644
--- a/sys/arch/i386/i386/mutex.S
+++ b/sys/arch/i386/i386/mutex.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.S,v 1.6 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.S,v 1.7 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -88,6 +88,51 @@ ENTRY(mtx_enter)
 	call	_C_LABEL(panic)
 6:	.asciz	"mtx_enter: locking against myself"
 #endif
+
+ENTRY(mtx_enter_try)
+	pushl	%ebp
+	movl	%esp, %ebp	
+1:	movl	SOFF(%ebp), %ecx
+	movl	MTX_WANTIPL(%ecx), %eax
+	movl	CPL, %edx		# oipl = cpl;
+	cmpl	%edx, %eax		# if (cpl < mtx->mtx_wantipl)
+	jle	2f
+	movl	%eax, CPL		#	cpl = mtx->mtx_wantipl;
+2:	/*
+	 * %edx now contains the oldipl.
+	 * %ecx contains the mtx.
+	 */
+	movl	$1, %eax
+	xchgl	%eax, MTX_LOCK(%ecx)	# test_and_set(mtx->mtx_lock)
+	testl	%eax, %eax		# if (already held)
+	jnz	3f
+	movl	CPUVAR(SELF), %eax
+	movl	%eax, MTX_OWNER(%ecx)
+	movl	%edx, MTX_OLDIPL(%ecx)
+	movl	$1, %eax
+	leave
+	ret
+
+	/* We failed to obtain the lock. splx and return zero. */
+3:	pushl	%edx
+	call	_C_LABEL(splx)
+	movl	%ebp, %esp
+	movl	SOFF(%ebp), %ecx		# %ecx clobbered
+#ifdef DIAGNOSTIC
+	movl	CPUVAR(SELF), %edx
+	cmpl	MTX_OWNER(%ecx), %edx
+	je	4f
+#endif
+	xorl	%eax, %eax
+	leave
+	ret
+
+#ifdef DIAGNOSTIC
+4:	pushl	$5f
+	call	_C_LABEL(panic)
+5:	.asciz	"mtx_enter: locking against myself"
+#endif
+
 	
 ENTRY(mtx_leave)
 	pushl	%ebp
diff --git a/sys/arch/m68k/m68k/mutex.c b/sys/arch/m68k/m68k/mutex.c
index d15931ef804..60943202b0d 100644
--- a/sys/arch/m68k/m68k/mutex.c
+++ b/sys/arch/m68k/m68k/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.3 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.4 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -58,6 +58,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _splraise(IPLTOPSL(mtx->mtx_wantipl));
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/m88k/m88k/mutex.S b/sys/arch/m88k/m88k/mutex.S
index 630805ca1be..78c3e2b9791 100644
--- a/sys/arch/m88k/m88k/mutex.S
+++ b/sys/arch/m88k/m88k/mutex.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.S,v 1.7 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.S,v 1.8 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2005, Miodrag Vallat.
@@ -126,6 +126,90 @@ enter_panic:
 #endif	/* MULTIPROCESSOR */
 	
 /*
+ * int mtx_enter_try(struct mutex *mtx)
+ */
+ENTRY(mtx_enter_try)
+	subu	r31, r31, 8
+	st	r1,  r31, 4		/* save return address */
+
+#ifdef MULTIPROCESSOR
+
+	st	r2,  r31, 0		/* save mtx */
+enter_try_again:
+	ld	r2,  r2,  MTX_WANTIPL
+	bcnd	eq0, r2,  1f
+	bsr	_C_LABEL(raiseipl)	/* raiseipl(mtx->mtx_wantipl) */
+1:
+	ld	r4,  r31, 0
+	or	r3,  r0,  1
+	xmem	r3,  r4,  r0		/* attempt to claim the lock, old */
+	bcnd	ne0, r3,  enter_try_failed /* mtx->mtx_lock is 0 if successful*/
+
+	ldcr	r3,  CPU
+	st	r2,  r4,  MTX_OLDIPL	/* save into mtx_oldipl */
+	st	r3,  r4,  MTX_CPU	/* mtx->mtx_cpu = curcpu() */
+
+	ld	r1,  r31, 4
+	or	r2,  r0,  1		/* return nonzero */
+	jmp.n	r1
+	 addu	r31, r31, 8
+
+enter_try_failed:	/* the lock is not ours... */
+	ld	r3,  r4,  MTX_WANTIPL
+	bcnd	eq0, r3,  2f
+	bcnd	ne0, r2,  1f		/* splx(oldipl) */
+	bsr.n	_C_LABEL(spl0)
+	 addu	r1,  r1,  2f - . - 4
+1:
+	bsr	_C_LABEL(setipl)
+2:
+#ifdef DIAGNOSTIC
+	ld	r2,  r31, 0		/* restore mtx */
+	ldcr	r3,  CPU
+	ld	r4,  r2,  MTX_CPU
+	cmp	r5,  r3,  r4
+	bcnd	eq0, r5,  enter_try_panic
+#endif
+	or	r2,  r0,  r0		/* return zero */
+	jmp.n	r1
+	 addu	r31, r31, 8
+
+#ifdef DIAGNOSTIC
+enter_try_panic:
+	or.u	r2,  r0,  hi16(9f)
+	bsr.n	_C_LABEL(panic)
+	 or	r2,  r2,  lo16(9f)
+
+	data
+9:
+	string	"mtx_enter_try: humpaan itsekseni"
+#endif
+
+#else	/* MULTIPROCESSOR */
+
+	st	r2,  r31, 0		/* save mtx */
+	ld	r2,  r2,  MTX_WANTIPL
+	bcnd	eq0, r2,  1f
+	bsr	_C_LABEL(raiseipl)	/* raiseipl(mtx->mtx_wantipl) */
+1:
+	ld	r4,  r31, 0
+	ldcr	r3,  CPU
+	st	r3,  r4,  MTX_LOCK	/* locked! */
+
+	st	r2,  r4,  MTX_OLDIPL	/* save into mtx_oldipl */
+
+#ifdef DIAGNOSTIC	/* necessary for MUTEX_ASSERT_LOCKED */
+	st	r3,  r4,  MTX_CPU	/* mtx->mtx_cpu = curcpu() */
+#endif
+
+	ld	r1,  r31, 4
+	or	r2,  r0,  1		/* return nonzero */
+	jmp.n	r1
+	 addu	r31, r31, 8
+
+#endif	/* MULTIPROCESSOR */
+	
+/*
  * void mtx_leave(struct mutex *mtx)
  */
 ENTRY(mtx_leave)
diff --git a/sys/arch/powerpc/powerpc/mutex.S b/sys/arch/powerpc/powerpc/mutex.S
index 06279171751..079d50aa3b2 100644
--- a/sys/arch/powerpc/powerpc/mutex.S
+++ b/sys/arch/powerpc/powerpc/mutex.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.S,v 1.9 2009/06/09 01:12:38 deraadt Exp $	*/
+/*	$OpenBSD: mutex.S,v 1.10 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2007 Dale Rahn
@@ -83,6 +83,61 @@ ENTRY(mtx_enter)
 #endif
 
 
+ENTRY(mtx_enter_try)
+	stwu	%r1,-32(%r1)			# reserve stack
+	mflr	%r0
+	stw	%r0,36(%r1)			# save return address
+	GET_CPUINFO(%r4)
+	lwz	%r5,MTX_WANTIPL(%r3)		# load new ipl
+	lis	%r6,_C_LABEL(imask)@ha		# convert into cpl
+	slwi	%r5,%r5,2
+	addi	%r5,%r5,_C_LABEL(imask)@l
+	lwzx	%r5,%r5,%r6
+	lwz	%r7,CI_CPL(%r4)			# load current cpl
+	or	%r6,%r5,%r7			# raise	cpl
+	stw	%r6,CI_CPL(%r4)			# store new cpl
+	li	%r5,MTX_OWNER			# load offset constant
+	lwarx	%r6,%r5,%r3			# load reserve owner
+	cmpwi	0,%r6,0				# test owner == 0
+	beq+	0,.L_mutex_try_free		# if owner == 0 branch free
+.L_mutex_try_locked:
+#ifdef DIAGNOSTIC
+	cmpl	0,%r4,%r6
+	beq-	.L_mutex_try_selflocked
+#endif
+	stw	%r3,28(%r1)			# save mtx during lcsplx
+	la	%r4,28(%r1)
+	stwcx.	%r3,0,%r4			# unreserve owner
+	mr	%r3,%r7				# move old cpl to arg0
+	bl	_C_LABEL(lcsplx)		# call splx on old cpl
+
+	lwz	%r0,36(%r1)			# load return address
+	mtlr	%r0
+	addi	%r1,%r1,32			# restore stack
+	li	%r2,0				# return zero
+	blr
+
+.L_mutex_try_free:
+	stwcx.	%r4,%r5,%r3			# old owner was 0 cond store
+	bne-	.L_mutex_try_locked		# branch if reserve cancelled
+	stw	%r7,MTX_OLDCPL(%r3)		# save old ipl
+	lwz	%r0,36(%r1)			# load return address
+	mtlr	%r0
+	addi	%r1,%r1,32			# restore stack
+	li	%r2,1				# return nonzero
+	blr
+
+#ifdef DIAGNOSTIC
+.L_mutex_try_selflocked:
+	mr	%r5, %r3
+	lis	%r3,.L_panictrylocked@ha
+	la	%r3,.L_panictrylocked@l(%r3)
+	bl 	panic
+.L_panictrylocked:
+	.string "mtx_enter_try: recursed %x %x\n"
+#endif
+
+
 ENTRY(mtx_leave)
 #ifdef DIAGNOSTIC
 	lwz	%r6,MTX_OWNER(%r3)
diff --git a/sys/arch/sgi/sgi/mutex.c b/sys/arch/sgi/sgi/mutex.c
index b13f3104921..687f0cb1486 100644
--- a/sys/arch/sgi/sgi/mutex.c
+++ b/sys/arch/sgi/sgi/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.4 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.5 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -58,6 +58,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = splraise(imask[mtx->mtx_wantipl]);
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/sh/sh/mutex.c b/sys/arch/sh/sh/mutex.c
index 591b434417f..66f08391e9b 100644
--- a/sys/arch/sh/sh/mutex.c
+++ b/sys/arch/sh/sh/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.3 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.4 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -57,6 +57,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _cpu_intr_raise(mtx->mtx_wantipl);
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/sparc/sparc/mutex.c b/sys/arch/sparc/sparc/mutex.c
index 98880e1e509..33605dcf826 100644
--- a/sys/arch/sparc/sparc/mutex.c
+++ b/sys/arch/sparc/sparc/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.3 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.4 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -63,6 +63,24 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	int psr;
+
+	if (mtx->mtx_wantipl != IPL_NONE << 8) {
+		psr = getpsr();
+		mtx->mtx_oldipl = psr & PSR_PIL;
+		if (mtx->mtx_oldipl < mtx->mtx_wantipl)
+			setpsr((psr & ~PSR_PIL) | mtx->mtx_wantipl);
+	}
+
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/arch/sparc64/sparc64/mutex.S b/sys/arch/sparc64/sparc64/mutex.S
index c7d085cdced..5ae4267c361 100644
--- a/sys/arch/sparc64/sparc64/mutex.S
+++ b/sys/arch/sparc64/sparc64/mutex.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.S,v 1.5 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.S,v 1.6 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2007 Mark Kettenis
@@ -75,6 +75,33 @@ ENTRY(mtx_enter)
 	retl
 	 membar	#LoadLoad | #LoadStore
 
+ENTRY(mtx_enter_try)
+	rdpr	%pil, %g4
+	GET_CURCPU(%g1)
+1:
+	ld	[%o0 + MTX_WANTIPL], %g5
+	bge	2f
+	 nop
+	wrpr	%g5, %pil
+2:
+	mov	%g1, %g5
+/*
+ * The assembler doesn't like the next line, even if MTX_OWNER is 0.
+ */
+!	casx	[%o0 + MTX_OWNER], %g0, %g5
+	casx	[%o0], %g0, %g5
+	tst	%g5
+	be	3f
+	 nop
+	wrpr	%g4, %pil
+	retl
+	 mov	0, %o0
+3:
+	stw	%g4, [%o0 + MTX_OLDIPL]
+	membar	#LoadLoad | #LoadStore
+	retl
+	 mov	1, %o0
+
 ENTRY(mtx_leave)
 	ld	[%o0 + MTX_OLDIPL], %g1
 	membar	#StoreStore | #LoadStore
diff --git a/sys/arch/vax/vax/mutex.c b/sys/arch/vax/vax/mutex.c
index 28e30677000..4b1ba96ae0e 100644
--- a/sys/arch/vax/vax/mutex.c
+++ b/sys/arch/vax/vax/mutex.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.c,v 1.3 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.c,v 1.4 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -57,6 +57,17 @@ mtx_enter(struct mutex *mtx)
 	mtx->mtx_lock = 1;
 }
 
+int
+mtx_enter_try(struct mutex *mtx)
+{
+	if (mtx->mtx_wantipl != IPL_NONE)
+		mtx->mtx_oldipl = _splraise(mtx->mtx_wantipl);
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+
+	return 1;
+}
+
 void
 mtx_leave(struct mutex *mtx)
 {
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h
index 76f4e00f22e..227470f5d70 100644
--- a/sys/sys/mutex.h
+++ b/sys/sys/mutex.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mutex.h,v 1.6 2009/04/27 21:48:56 kettenis Exp $	*/
+/*	$OpenBSD: mutex.h,v 1.7 2009/08/13 13:24:55 weingart Exp $	*/
 
 /*
  * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
@@ -52,5 +52,6 @@ void mtx_init(struct mutex *, int);
 #endif
 void mtx_enter(struct mutex *);
 void mtx_leave(struct mutex *);
+int mtx_enter_try(struct mutex *);
 
 #endif