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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Alan Stern 2005-11-04 14:44:41 -05:00 committed by James Bottomley
parent 0ee957cb7a
commit 39b7f1e25a
1 changed files with 61 additions and 36 deletions
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97
drivers/scsi/sd.c
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@ -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;
if (disk->private_data) {
sdkp = scsi_disk(disk);
if (scsi_device_get(sdkp->device) == 0)
kref_get(&sdkp->kref);
else
sdkp = NULL;
}
return sdkp;
}
static struct scsi_disk *scsi_disk_get(struct gendisk *disk)
{
struct scsi_disk *sdkp;
down(&sd_ref_sem);
if (disk->private_data == NULL)
goto out;
sdkp = scsi_disk(disk);
kref_get(&sdkp->kref);
if (scsi_device_get(sdkp->device))
goto out_put;
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->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;
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;
ret = 1;
}
scsi_disk_put(sdkp);
}
return 0;
return ret;
}
static void sd_rescan(struct device *dev)
{
struct scsi_disk *sdkp = dev_get_drvdata(dev);
sd_revalidate_disk(sdkp->disk);
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;
printk(KERN_NOTICE "Synchronizing SCSI cache for disk %s: \n",
sdkp->disk->disk_name);
sd_sync_cache(sdp);
}
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