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Date:      Tue, 9 Jul 2002 14:21:34 -0700 (PDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Perforce Change Reviews <perforce@freebsd.org>
Subject:   PERFORCE change 13995 for review
Message-ID:  <200207092121.g69LLYBh092119@freefall.freebsd.org>
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http://people.freebsd.org/~peter/p4db/chv.cgi?CH=13995

Change 13995 by jhb@jhb_laptop on 2002/07/09 14:21:31

	Get rid of gross mtx_owned()'s.  This still isn't pretty.
	I need to figure out a better way of handling this.

Affected files ...

.. //depot/projects/smpng/sys/i386/i386/machdep.c#40 edit
.. //depot/projects/smpng/sys/i386/i386/sys_machdep.c#20 edit
.. //depot/projects/smpng/sys/i386/i386/vm_machdep.c#22 edit
.. //depot/projects/smpng/sys/i386/include/proc.h#7 edit

Differences ...

==== //depot/projects/smpng/sys/i386/i386/machdep.c#40 (text+ko) ====

@@ -825,8 +825,11 @@
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
+	mtx_lock_spin(&sched_lock);
 	if (td->td_proc->p_md.md_ldt)
 		user_ldt_free(td);
+	else
+		mtx_unlock_spin(&sched_lock);
   
 	bzero((char *)regs, sizeof(struct trapframe));
 	regs->tf_eip = entry;

==== //depot/projects/smpng/sys/i386/i386/sys_machdep.c#20 (text+ko) ====

@@ -286,7 +286,7 @@
 #endif
 
 /*
- * Must be called with either sched_lock free or held but not recursed.
+ * Must be called with sched_lock held but not recursed.
  * If it does not return NULL, it will return with it owned.
  */
 struct proc_ldt *
@@ -294,9 +294,8 @@
 {
 	struct proc_ldt *pldt, *new_ldt;
 
-	if (mtx_owned(&sched_lock))
-		mtx_unlock_spin(&sched_lock);
-	mtx_assert(&sched_lock, MA_NOTOWNED);
+	mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
+	mtx_unlock_spin(&sched_lock);
 	MALLOC(new_ldt, struct proc_ldt *, sizeof(struct proc_ldt),
 		M_SUBPROC, M_WAITOK);
 
@@ -327,7 +326,7 @@
 }
 
 /*
- * Must be called either with sched_lock free or held but not recursed.
+ * Must be called with sched_lock held but not recursed.
  * If md_ldt is not NULL, it will return with sched_lock released.
  */
 void
@@ -339,8 +338,6 @@
 	if (pldt == NULL)
 		return;
 
-	if (!mtx_owned(&sched_lock))
-		mtx_lock_spin(&sched_lock);
 	mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
 	if (td == PCPU_GET(curthread)) {
 		lldt(_default_ldt);
@@ -407,7 +404,7 @@
 	int error = 0, i, n;
 	int largest_ld;
 	struct mdproc *mdp = &td->td_proc->p_md;
-	struct proc_ldt *pldt = mdp->md_ldt;
+	struct proc_ldt *pldt;
 	struct i386_ldt_args ua, *uap = &ua;
 	caddr_t old_ldt_base;
 	int old_ldt_len;
@@ -432,8 +429,12 @@
 		return(EINVAL);
 
 	/* allocate user ldt */
+	mtx_lock_spin(&sched_lock);
+	pldt = mdp->md_ldt;
 	if (!pldt || largest_ld >= pldt->ldt_len) {
-		struct proc_ldt *new_ldt = user_ldt_alloc(mdp, largest_ld);
+		struct proc_ldt *new_ldt;
+
+		new_ldt = user_ldt_alloc(mdp, largest_ld);
 		if (new_ldt == NULL)
 			return ENOMEM;
 		if (pldt) {
@@ -463,7 +464,8 @@
 		set_user_ldt(mdp);
 		mtx_unlock_spin(&sched_lock);
 #endif
-	}
+	} else
+		mtx_unlock_spin(&sched_lock);
 
 	/* Check descriptors for access violations */
 	for (i = 0, n = uap->start; i < uap->num; i++, n++) {

==== //depot/projects/smpng/sys/i386/i386/vm_machdep.c#22 (text+ko) ====

@@ -135,7 +135,10 @@
 		if ((flags & RFMEM) == 0) {
 			/* unshare user LDT */
 			struct mdproc *mdp1 = &p1->p_md;
-			struct proc_ldt *pldt = mdp1->md_ldt;
+			struct proc_ldt *pldt;
+
+			mtx_lock_spin(&sched_lock);
+			pltd = mdp1->md_ldt;
 			if (pldt && pldt->ldt_refcnt > 1) {
 				pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
 				if (pldt == NULL)
@@ -143,7 +146,8 @@
 				mdp1->md_ldt = pldt;
 				set_user_ldt(mdp1);
 				user_ldt_free(td1);
-			}
+			} else
+				mtx_unlock_spin(&sched_lock);
 		}
 		return;
 	}
@@ -210,7 +214,7 @@
 
         /* Copy the LDT, if necessary. */
 	mtx_lock_spin(&sched_lock);
-        if (mdp2->md_ldt != 0) {
+        if (mdp2->md_ldt != NULL) {
 		if (flags & RFMEM) {
 			mdp2->md_ldt->ldt_refcnt++;
 		} else {
@@ -271,8 +275,11 @@
 		    ctob(IOPAGES + 1));
 		pcb->pcb_ext = 0;
 	}
+	mtx_lock_spin(&sched_lock);
 	if (mdp->md_ldt)
 		user_ldt_free(td);
+	else
+		mtx_unlock_spin(&sched_lock);
         if (pcb->pcb_flags & PCB_DBREGS) {
                 /*
                  * disable all hardware breakpoints

==== //depot/projects/smpng/sys/i386/include/proc.h#7 (text+ko) ====

@@ -55,7 +55,7 @@
 };
 
 struct mdproc {
-	struct proc_ldt *md_ldt;	/* per-process ldt */
+	struct proc_ldt *md_ldt;	/* (j) per-process ldt */
 };
 
 #ifdef	_KERNEL

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