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Date:      Wed, 5 Jun 2002 10:40:17 +0800
From:      "kai ouyang" <oykai@msn.com>
To:        "John Baldwin" <jhb@FreeBSD.org>, <current@FreeBSD.org>
Subject:   Please help: why bufwait() will cause the thread status change to SSLEEP?
Message-ID:  <OE41l4maEqxGGmNN79x00013818@hotmail.com>
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I do not know the thread group means what in FreeBSD5.0.
Could you give me some information?
Now, I mask the code about thread group operations.
When I want to get the RAIDFrame information(exist in the disk block).
I can call raidread_component_label(), as the following:
int raidread_component_label(dev, b_vp, clabel)
	udev_t dev;
	struct vnode *b_vp;
	RF_ComponentLabel_t *clabel;
{
		
	struct buf *bp;
	int error;
		
	/* XXX should probably ensure that we don't try to do this if
	   someone has changed rf_protected_sectors. */  
	if (b_vp == NULL) {
		/* For whatever reason, this component is not valid.
		   Don't try to read a component label from it. */
		return(EINVAL);
	}

	/* get a block of the appropriate size... */
	bp = geteblk((int)RF_COMPONENT_INFO_SIZE);
	bp->b_dev = udev2dev(dev, 0);

	/* get our ducks in a row for the read */
	bp->b_blkno = RF_COMPONENT_INFO_OFFSET / DEV_BSIZE;
	bp->b_bcount = RF_COMPONENT_INFO_SIZE;
	/*oyk add here to support FreeBSD5.0*/
	bp->b_flags |= BIO_READ;
 	bp->b_resid = RF_COMPONENT_INFO_SIZE / DEV_BSIZE;
	DEV_STRATEGY(bp, 0);
	error = bufwait(bp);
        bp->b_flags |= B_INVAL | B_AGE;
        bp->b_ioflags &= ~BIO_ERROR;
      	if (!error) {
		memcpy(clabel, bp->b_data,
		       sizeof(RF_ComponentLabel_t));

        }
	brelse(bp);  
	return(error);
}

Now, when I excute the 'error = bufwait(bp);', the system will be crash. the error information
is also thread status SSLEEP.
I do know what will cause the thread status change to SSLEEP.
The function in FreeBSD4.x as following:
int raidread_component_label(dev, b_vp, clabel)
	udev_t dev;
	struct vnode *b_vp;
	RF_ComponentLabel_t *clabel;
{
	struct buf *bp;
	int error;
		
	/* XXX should probably ensure that we don't try to do this if
	   someone has changed rf_protected_sectors. */  

	if (b_vp == NULL) {
		/* For whatever reason, this component is not valid.
		   Don't try to read a component label from it. */
		return(EINVAL);
	}

	/* get a block of the appropriate size... */
	bp = geteblk((int)RF_COMPONENT_INFO_SIZE);
	bp->b_dev = udev2dev(dev, 0);

	/* get our ducks in a row for the read */
	bp->b_blkno = RF_COMPONENT_INFO_OFFSET / DEV_BSIZE;
	bp->b_bcount = RF_COMPONENT_INFO_SIZE;
	bp->b_flags |= B_READ;
 	bp->b_resid = RF_COMPONENT_INFO_SIZE / DEV_BSIZE;

	BUF_STRATEGY(bp, 0);

	error = biowait(bp);  

	if (!error) {
		memcpy(clabel, bp->b_data,
		       sizeof(RF_ComponentLabel_t));
        }
	brelse(bp);  
	return(error);
}
 I transfer it to FreeBSD5.0 according vinum example.
help

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