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Date:      Wed, 15 Sep 2010 15:33:51 +0000 (UTC)
From:      Matthew D Fleming <mdf@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org
Subject:   svn commit: r212664 - in stable/7/sys: kern sys
Message-ID:  <201009151533.o8FFXpQS040837@svn.freebsd.org>
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Author: mdf
Date: Wed Sep 15 15:33:51 2010
New Revision: 212664
URL: http://svn.freebsd.org/changeset/base/212664

Log:
  Revert r212563, which was a MFC of r209053, as it introduced an unlocked
  read/modify/write of b_vflags.  The unlocked access is fixed in CURRENT
  and stable/8 by r211213 and its MFC, r212583.
  
  Rather than MFC to stable/7, reverting the injecting code seems
  preferable.

Modified:
  stable/7/sys/kern/vfs_bio.c
  stable/7/sys/sys/buf.h
Directory Properties:
  stable/7/sys/   (props changed)
  stable/7/sys/cddl/contrib/opensolaris/   (props changed)
  stable/7/sys/contrib/dev/acpica/   (props changed)
  stable/7/sys/contrib/pf/   (props changed)

Modified: stable/7/sys/kern/vfs_bio.c
==============================================================================
--- stable/7/sys/kern/vfs_bio.c	Wed Sep 15 15:18:41 2010	(r212663)
+++ stable/7/sys/kern/vfs_bio.c	Wed Sep 15 15:33:51 2010	(r212664)
@@ -381,16 +381,10 @@ runningbufwakeup(struct buf *bp)
  */
 
 static __inline void
-bufcountwakeup(struct buf *bp) 
+bufcountwakeup(void) 
 {
-	int old;
 
-	KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
-	    ("buf %p already counted as free", bp));
-	bp->b_vflags |= BV_INFREECNT;
-	old = atomic_fetchadd_int(&numfreebuffers, 1);
-	KASSERT(old >= 0 && old < nbuf,
-	    ("numfreebuffers climbed to %d", old + 1));
+	atomic_add_int(&numfreebuffers, 1);
 	mtx_lock(&nblock);
 	if (needsbuffer) {
 		needsbuffer &= ~VFS_BIO_NEED_ANY;
@@ -593,7 +587,7 @@ bufinit(void)
 		bp->b_rcred = NOCRED;
 		bp->b_wcred = NOCRED;
 		bp->b_qindex = QUEUE_EMPTY;
-		bp->b_vflags = BV_INFREECNT;	/* buf is counted as free */
+		bp->b_vflags = 0;
 		bp->b_xflags = 0;
 		LIST_INIT(&bp->b_dep);
 		BUF_LOCKINIT(bp);
@@ -694,7 +688,6 @@ bfreekva(struct buf *bp)
 void
 bremfree(struct buf *bp)
 {
-	int old;
 
 	CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 	KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
@@ -705,13 +698,8 @@ bremfree(struct buf *bp)
 
 	bp->b_flags |= B_REMFREE;
 	/* Fixup numfreebuffers count.  */
-	if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
-		KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
-		    ("buf %p not counted in numfreebuffers", bp));
-		bp->b_vflags &= ~BV_INFREECNT;
-		old = atomic_fetchadd_int(&numfreebuffers, -1);
-		KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
-	}
+	if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
+		atomic_subtract_int(&numfreebuffers, 1);
 }
 
 /*
@@ -737,8 +725,6 @@ bremfreef(struct buf *bp)
 static void
 bremfreel(struct buf *bp)
 {
-	int old;
-
 	CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
 	    bp, bp->b_vp, bp->b_flags);
 	KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp));
@@ -761,13 +747,8 @@ bremfreel(struct buf *bp)
 	 * delayed-write, the buffer was free and we must decrement
 	 * numfreebuffers.
 	 */
-	if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
-		KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
-		    ("buf %p not counted in numfreebuffers", bp));
-		bp->b_vflags &= ~BV_INFREECNT;
-		old = atomic_fetchadd_int(&numfreebuffers, -1);
-		KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
-	}
+	if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
+		atomic_subtract_int(&numfreebuffers, 1);
 }
 
 
@@ -1471,7 +1452,7 @@ brelse(struct buf *bp)
 	 */
 
 	if (!(bp->b_flags & B_DELWRI))
-		bufcountwakeup(bp);
+		bufcountwakeup();
 
 	/*
 	 * Something we can maybe free or reuse
@@ -1561,7 +1542,7 @@ bqrelse(struct buf *bp)
 	mtx_unlock(&bqlock);
 
 	if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
-		bufcountwakeup(bp);
+		bufcountwakeup();
 
 	/*
 	 * Something we can maybe free or reuse.
@@ -1941,8 +1922,6 @@ restart:
 		bp->b_flags = 0;
 		bp->b_ioflags = 0;
 		bp->b_xflags = 0;
-		KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
-		    ("buf %p still counted as free?", bp));
 		bp->b_vflags = 0;
 		bp->b_vp = NULL;
 		bp->b_blkno = bp->b_lblkno = 0;
@@ -4104,27 +4083,4 @@ DB_SHOW_COMMAND(vnodebufs, db_show_vnode
 		db_printf("\n");
 	}
 }
-
-DB_COMMAND(countfreebufs, db_coundfreebufs)
-{
-	struct buf *bp;
-	int i, used = 0, nfree = 0;
-
-	if (have_addr) {
-		db_printf("usage: countfreebufs\n");
-		return;
-	}
-
-	for (i = 0; i < nbuf; i++) {
-		bp = &buf[i];
-		if ((bp->b_vflags & BV_INFREECNT) != 0)
-			nfree++;
-		else
-			used++;
-	}
-
-	db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
-	    nfree + used);
-	db_printf("numfreebuffers is %d\n", numfreebuffers);
-}
 #endif /* DDB */

Modified: stable/7/sys/sys/buf.h
==============================================================================
--- stable/7/sys/sys/buf.h	Wed Sep 15 15:18:41 2010	(r212663)
+++ stable/7/sys/sys/buf.h	Wed Sep 15 15:33:51 2010	(r212664)
@@ -247,7 +247,6 @@ struct buf {
 #define	BV_SCANNED	0x00000001	/* VOP_FSYNC funcs mark written bufs */
 #define	BV_BKGRDINPROG	0x00000002	/* Background write in progress */
 #define	BV_BKGRDWAIT	0x00000004	/* Background write waiting */
-#define	BV_INFREECNT	0x80000000	/* buf is counted in numfreebufs */
 
 #ifdef _KERNEL
 /*

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