Change and clean the mutex lock interface.

mtx_enter(lock, type) becomes:

mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)

similarily, for releasing a lock, we now have:

mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.

The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.

Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:

MTX_QUIET and MTX_NOSWITCH

The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:

mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.

Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.

Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.

Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.

Finally, caught up to the interface changes in all sys code.

Contributors: jake, jhb, jasone (in no particular order)

1 files changed, 66 insertions, 23 deletions

diff --git a/sys/amd64/include/mutex.h b/sys/amd64/include/mutex.h
index 2f16de3..c4fe210 100644
--- a/sys/amd64/include/mutex.h
+++ b/sys/amd64/include/mutex.h
@@ -43,22 +43,10 @@ extern struct mtx	clock_lock;
 /*
  * Debugging
  */
-#ifdef MUTEX_DEBUG
-
-#ifdef _KERN_MUTEX_C_
-char STR_IEN[] = "fl & PSL_I";
-char STR_IDIS[] = "!(fl & PSL_I)";
-char STR_SIEN[] = "mpp->mtx_saveintr & PSL_I";
-#else	/* _KERN_MUTEX_C_ */
-extern char STR_IEN[];
-extern char STR_IDIS[];
-extern char STR_SIEN[];
-#endif	/* _KERN_MUTEX_C_ */
-#endif	/* MUTEX_DEBUG */
-
-#define	ASS_IEN		MPASS2(read_eflags() & PSL_I, STR_IEN)
-#define	ASS_IDIS	MPASS2((read_eflags() & PSL_I) == 0, STR_IDIS)
-#define ASS_SIEN(mpp)	MPASS2((mpp)->mtx_saveintr & PSL_I, STR_SIEN)
+#define	ASS_IEN		MPASS2(read_eflags() & PSL_I, "fl & PSL_I")
+#define	ASS_IDIS	MPASS2((read_eflags() & PSL_I) == 0, "!(fl & PSL_I)")
+#define ASS_SIEN(mpp)	MPASS2((mpp)->mtx_saveintr & PSL_I,		\
+			"mpp->mtx_saveintr & PSL_I")
 
 #define	mtx_legal2block()	(read_eflags() & PSL_I)
 
@@ -66,9 +54,6 @@ extern char STR_SIEN[];
  * Assembly macros (for internal use only)
  *------------------------------------------------------------------------------
  */
-
-#ifdef _KERN_MUTEX_C_
-
 #define	_V(x)	__STRING(x)
 
 #if 0
@@ -252,22 +237,80 @@ extern char STR_SIEN[];
 
 #undef _V
 
-#endif	/* _KERN_MUTEX_C_ */
-
 #endif	/* _KERNEL */
 
 #else	/* !LOCORE */
 
 /*
  * Simple assembly macros to get and release mutexes.
+ *
+ * Note: All of these macros accept a "flags" argument and are analoguous
+ *	 to the mtx_lock_flags and mtx_unlock_flags general macros. If one
+ *	 desires to not pass a flag, the value 0 may be passed as second
+ *	 argument.
+ *
+ * XXX: We only have MTX_LOCK_SPIN and MTX_UNLOCK_SPIN for now, since that's
+ *	all we use right now. We should add MTX_LOCK and MTX_UNLOCK (for sleep
+ *	locks) in the near future, however.
  */
+#define MTX_LOCK_SPIN(lck, flags)					\
+	pushl %eax ;							\
+	pushl %ecx ;							\
+	pushl %ebx ;							\
+	movl $(MTX_UNOWNED) , %eax ;					\
+	movl PCPU(CURPROC), %ebx ;					\
+	pushfl ;							\
+	popl %ecx ;							\
+	cli ;								\
+	MPLOCKED cmpxchgl %ebx, lck+MTX_LOCK ;				\
+	jz 2f ;								\
+	cmpl lck+MTX_LOCK, %ebx ;					\
+	je 3f ;								\
+	pushl $0 ;							\
+	pushl $0 ;							\
+	pushl %ecx ;							\
+	pushl $flags ;							\
+	pushl $lck ;							\
+	call _mtx_lock_spin ;						\
+	addl $0x14, %esp ;						\
+	jmp 1f ;							\
+3:	movl lck+MTX_RECURSECNT, %ebx ;					\
+	incl %ebx ;							\
+	movl %ebx, lck+MTX_RECURSECNT ;					\
+	jmp 1f ;							\
+2:	movl %ecx, lck+MTX_SAVEINTR ;					\
+1:	popl %ebx ;							\
+	popl %ecx ;							\
+	popl %eax
+
+#define MTX_UNLOCK_SPIN(lck)						\
+	pushl %edx ;							\
+	pushl %eax ;							\
+	movl lck+MTX_SAVEINTR, %edx ;					\
+	movl lck+MTX_RECURSECNT, %eax ;					\
+	testl %eax, %eax ;						\
+	jne 2f ;							\
+	movl $(MTX_UNOWNED), %eax ;					\
+	xchgl %eax, lck+MTX_LOCK ;					\
+	pushl %edx ;							\
+	popfl ;								\
+	jmp 1f ;							\
+2:	decl %eax ;							\
+	movl %eax, lck+MTX_RECURSECNT ;					\
+1:	popl %eax ;							\
+	popl %edx
 
+/*
+ * XXX: These two are broken right now and need to be made to work for
+ * XXX: sleep locks, as the above two work for spin locks. We're not in
+ * XXX: too much of a rush to do these as we do not use them right now.
+ */
 #define	MTX_ENTER(lck, type)						\
 	pushl	$0 ;				/* dummy __LINE__ */	\
 	pushl	$0 ;				/* dummy __FILE__ */	\
 	pushl	$type ;							\
 	pushl	$lck ;							\
-	call	_mtx_enter ;						\
+	call	_mtx_lock_XXX ;						\
 	addl	$16,%esp
 
 #define	MTX_EXIT(lck, type)						\
@@ -275,7 +318,7 @@ extern char STR_SIEN[];
 	pushl	$0 ;				/* dummy __FILE__ */	\
 	pushl	$type ;							\
 	pushl	$lck ;							\
-	call	_mtx_exit ;						\
+	call	_mtx_unlock_XXX ;					\
 	addl	$16,%esp
 
 #endif	/* !LOCORE */