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Commit 39b7f1e2 authored by Alan Stern's avatar Alan Stern Committed by James Bottomley
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[SCSI] sd: Fix refcounting 



Currently the driver takes a reference only for requests coming by way
of the gendisk, not for requests coming by way of the struct device or
struct scsi_device.  Such requests can arrive in the rescan, flush,
and shutdown pathways.

The patch also makes the scsi_disk keep a reference to the underlying
scsi_device, and it erases the scsi_device's pointer to the scsi_disk
when the scsi_device is removed (since the pointer should no longer be
used).

This resolves Bugzilla entry #5237.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 0ee957cb

drivers/scsi/sd.c

+62 −37
Original line number Diff line number Diff line
@@ -177,24 +177,38 @@ static inline struct scsi_disk *scsi_disk(struct gendisk *disk) 
	return container_of(disk->private_data, struct scsi_disk, driver);

}



static struct scsi_disk *scsi_disk_get(struct gendisk *disk)

static struct scsi_disk *__scsi_disk_get(struct gendisk *disk)

{

	struct scsi_disk *sdkp = NULL;



	down(&sd_ref_sem);

	if (disk->private_data == NULL)

		goto out;

	if (disk->private_data) {

		sdkp = scsi_disk(disk);

		if (scsi_device_get(sdkp->device) == 0)

			kref_get(&sdkp->kref);

	if (scsi_device_get(sdkp->device))

		goto out_put;

		else

			sdkp = NULL;

	}

	return sdkp;

}



static struct scsi_disk *scsi_disk_get(struct gendisk *disk)

{

	struct scsi_disk *sdkp;



	down(&sd_ref_sem);

	sdkp = __scsi_disk_get(disk);

	up(&sd_ref_sem);

	return sdkp;

}



 out_put:

	kref_put(&sdkp->kref, scsi_disk_release);

	sdkp = NULL;

 out:

static struct scsi_disk *scsi_disk_get_from_dev(struct device *dev)

{

	struct scsi_disk *sdkp;



	down(&sd_ref_sem);

	sdkp = dev_get_drvdata(dev);

	if (sdkp)

		sdkp = __scsi_disk_get(sdkp->disk);

	up(&sd_ref_sem);

	return sdkp;

}
@@ -716,16 +730,17 @@ static int sd_sync_cache(struct scsi_device *sdp) 


static int sd_issue_flush(struct device *dev, sector_t *error_sector)

{

	int ret = 0;

	struct scsi_device *sdp = to_scsi_device(dev);

	struct scsi_disk *sdkp = dev_get_drvdata(dev);

	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);



	if (!sdkp)

               return -ENODEV;



	if (!sdkp->WCE)

		return 0;



	return sd_sync_cache(sdp);

	if (sdkp->WCE)

		ret = sd_sync_cache(sdp);

	scsi_disk_put(sdkp);

	return ret;

}



static void sd_end_flush(request_queue_t *q, struct request *flush_rq)
@@ -754,23 +769,30 @@ static void sd_end_flush(request_queue_t *q, struct request *flush_rq) 
static int sd_prepare_flush(request_queue_t *q, struct request *rq)

{

	struct scsi_device *sdev = q->queuedata;

	struct scsi_disk *sdkp = dev_get_drvdata(&sdev->sdev_gendev);

	struct scsi_disk *sdkp = scsi_disk_get_from_dev(&sdev->sdev_gendev);

	int ret = 0;



	if (sdkp) {

		if (sdkp->WCE) {

			memset(rq->cmd, 0, sizeof(rq->cmd));

			rq->flags |= REQ_BLOCK_PC | REQ_SOFTBARRIER;

			rq->timeout = SD_TIMEOUT;

			rq->cmd[0] = SYNCHRONIZE_CACHE;

		return 1;

			ret = 1;

		}



	return 0;

		scsi_disk_put(sdkp);

	}

	return ret;

}



static void sd_rescan(struct device *dev)

{

	struct scsi_disk *sdkp = dev_get_drvdata(dev);

	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);



	if (sdkp) {

		sd_revalidate_disk(sdkp->disk);

		scsi_disk_put(sdkp);

	}

}
@@ -1561,6 +1583,7 @@ static int sd_probe(struct device *dev) 
	if (error)

		goto out_put;



	get_device(&sdp->sdev_gendev);

	sdkp->device = sdp;

	sdkp->driver = &sd_template;

	sdkp->disk = gd;
@@ -1637,7 +1660,9 @@ static int sd_remove(struct device *dev) 


	del_gendisk(sdkp->disk);

	sd_shutdown(dev);



	down(&sd_ref_sem);

	dev_set_drvdata(dev, NULL);

	kref_put(&sdkp->kref, scsi_disk_release);

	up(&sd_ref_sem);
@@ -1663,8 +1688,8 @@ static void scsi_disk_release(struct kref *kref) 
	spin_unlock(&sd_index_lock);



	disk->private_data = NULL;



	put_disk(disk);

	put_device(&sdkp->device->sdev_gendev);



	kfree(sdkp);

}
@@ -1677,18 +1702,18 @@ static void scsi_disk_release(struct kref *kref) 
static void sd_shutdown(struct device *dev)

{

	struct scsi_device *sdp = to_scsi_device(dev);

	struct scsi_disk *sdkp = dev_get_drvdata(dev);

	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);



	if (!sdkp)

		return;         /* this can happen */



	if (!sdkp->WCE)

		return;



	if (sdkp->WCE) {

		printk(KERN_NOTICE "Synchronizing SCSI cache for disk %s: \n",

				sdkp->disk->disk_name);

		sd_sync_cache(sdp);

	}

	scsi_disk_put(sdkp);

}



/**

 *	init_sd - entry point for this driver (both when built in or when