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authorAlan Stern <stern@rowland.harvard.edu>2005-11-04 14:44:41 -0500
committerJames Bottomley <jejb@mulgrave.(none)>2005-11-05 09:52:24 -0600
commit39b7f1e25a412b0ef31e516cfc2fa4f40235f263 (patch)
treeff9d9c44b6199624d87af0d4776f2ecfd18f2635
parent0ee957cb7a8f6e4fb8c6f943dbc451957bc0c6bc (diff)
[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>
-rw-r--r--drivers/scsi/sd.c99
1 files changed, 62 insertions, 37 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 9de8e186cb69..bb5b242ac6b4 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -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);
-
- 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;
+ 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;
+ 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