From 39b7f1e25a412b0ef31e516cfc2fa4f40235f263 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Fri, 4 Nov 2005 14:44:41 -0500 Subject: [PATCH] [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 Signed-off-by: James Bottomley --- drivers/scsi/sd.c | 99 +++++++++++++++++++++++++++++------------------ 1 file 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 -- 2.20.1