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sr: implement ->free_disk to simplify refcounting
Simplify the refcounting and remove the need to clear disk->private_data by implementing the ->free_disk method. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20220308055200.735835-9-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
Jens Axboe
parent
9c63f7f6ff
commit
01d0c69853
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@ -109,11 +109,6 @@ static DEFINE_SPINLOCK(sr_index_lock);
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static struct lock_class_key sr_bio_compl_lkclass;
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/* This semaphore is used to mediate the 0->1 reference get in the
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* face of object destruction (i.e. we can't allow a get on an
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* object after last put) */
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static DEFINE_MUTEX(sr_ref_mutex);
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static int sr_open(struct cdrom_device_info *, int);
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static void sr_release(struct cdrom_device_info *);
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@ -143,8 +138,6 @@ static const struct cdrom_device_ops sr_dops = {
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.capability = SR_CAPABILITIES,
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};
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static void sr_kref_release(struct kref *kref);
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static inline struct scsi_cd *scsi_cd(struct gendisk *disk)
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{
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return disk->private_data;
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@ -163,38 +156,6 @@ static int sr_runtime_suspend(struct device *dev)
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return 0;
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}
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/*
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* The get and put routines for the struct scsi_cd. Note this entity
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* has a scsi_device pointer and owns a reference to this.
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*/
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static inline struct scsi_cd *scsi_cd_get(struct gendisk *disk)
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{
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struct scsi_cd *cd = NULL;
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mutex_lock(&sr_ref_mutex);
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if (disk->private_data == NULL)
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goto out;
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cd = scsi_cd(disk);
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kref_get(&cd->kref);
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if (scsi_device_get(cd->device)) {
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kref_put(&cd->kref, sr_kref_release);
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cd = NULL;
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}
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out:
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mutex_unlock(&sr_ref_mutex);
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return cd;
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}
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static void scsi_cd_put(struct scsi_cd *cd)
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{
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struct scsi_device *sdev = cd->device;
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mutex_lock(&sr_ref_mutex);
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kref_put(&cd->kref, sr_kref_release);
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scsi_device_put(sdev);
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mutex_unlock(&sr_ref_mutex);
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}
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static unsigned int sr_get_events(struct scsi_device *sdev)
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{
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u8 buf[8];
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@ -522,15 +483,13 @@ static void sr_revalidate_disk(struct scsi_cd *cd)
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static int sr_block_open(struct block_device *bdev, fmode_t mode)
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{
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struct scsi_cd *cd;
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struct scsi_device *sdev;
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struct scsi_cd *cd = cd = scsi_cd(bdev->bd_disk);
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struct scsi_device *sdev = cd->device;
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int ret = -ENXIO;
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cd = scsi_cd_get(bdev->bd_disk);
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if (!cd)
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goto out;
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if (scsi_device_get(cd->device))
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return -ENXIO;
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sdev = cd->device;
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scsi_autopm_get_device(sdev);
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if (bdev_check_media_change(bdev))
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sr_revalidate_disk(cd);
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@ -541,9 +500,7 @@ static int sr_block_open(struct block_device *bdev, fmode_t mode)
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scsi_autopm_put_device(sdev);
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if (ret)
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scsi_cd_put(cd);
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out:
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scsi_device_put(cd->device);
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return ret;
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}
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@ -555,7 +512,7 @@ static void sr_block_release(struct gendisk *disk, fmode_t mode)
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cdrom_release(&cd->cdi, mode);
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mutex_unlock(&cd->lock);
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scsi_cd_put(cd);
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scsi_device_put(cd->device);
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}
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static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
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@ -595,18 +552,24 @@ out:
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static unsigned int sr_block_check_events(struct gendisk *disk,
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unsigned int clearing)
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{
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unsigned int ret = 0;
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struct scsi_cd *cd;
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struct scsi_cd *cd = disk->private_data;
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cd = scsi_cd_get(disk);
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if (!cd)
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if (atomic_read(&cd->device->disk_events_disable_depth))
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return 0;
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return cdrom_check_events(&cd->cdi, clearing);
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}
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if (!atomic_read(&cd->device->disk_events_disable_depth))
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ret = cdrom_check_events(&cd->cdi, clearing);
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static void sr_free_disk(struct gendisk *disk)
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{
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struct scsi_cd *cd = disk->private_data;
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scsi_cd_put(cd);
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return ret;
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spin_lock(&sr_index_lock);
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clear_bit(MINOR(disk_devt(disk)), sr_index_bits);
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spin_unlock(&sr_index_lock);
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unregister_cdrom(&cd->cdi);
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mutex_destroy(&cd->lock);
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kfree(cd);
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}
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static const struct block_device_operations sr_bdops =
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@ -617,6 +580,7 @@ static const struct block_device_operations sr_bdops =
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.ioctl = sr_block_ioctl,
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.compat_ioctl = blkdev_compat_ptr_ioctl,
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.check_events = sr_block_check_events,
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.free_disk = sr_free_disk,
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};
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static int sr_open(struct cdrom_device_info *cdi, int purpose)
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@ -660,8 +624,6 @@ static int sr_probe(struct device *dev)
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if (!cd)
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goto fail;
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kref_init(&cd->kref);
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disk = __alloc_disk_node(sdev->request_queue, NUMA_NO_NODE,
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&sr_bio_compl_lkclass);
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if (!disk)
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@ -727,10 +689,8 @@ static int sr_probe(struct device *dev)
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sr_revalidate_disk(cd);
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error = device_add_disk(&sdev->sdev_gendev, disk, NULL);
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if (error) {
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kref_put(&cd->kref, sr_kref_release);
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goto fail;
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}
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if (error)
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goto unregister_cdrom;
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sdev_printk(KERN_DEBUG, sdev,
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"Attached scsi CD-ROM %s\n", cd->cdi.name);
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@ -738,6 +698,8 @@ static int sr_probe(struct device *dev)
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return 0;
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unregister_cdrom:
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unregister_cdrom(&cd->cdi);
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fail_minor:
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spin_lock(&sr_index_lock);
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clear_bit(minor, sr_index_bits);
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@ -1009,36 +971,6 @@ out_put_request:
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return ret;
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}
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/**
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* sr_kref_release - Called to free the scsi_cd structure
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* @kref: pointer to embedded kref
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*
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* sr_ref_mutex must be held entering this routine. Because it is
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* called on last put, you should always use the scsi_cd_get()
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* scsi_cd_put() helpers which manipulate the semaphore directly
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* and never do a direct kref_put().
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**/
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static void sr_kref_release(struct kref *kref)
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{
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struct scsi_cd *cd = container_of(kref, struct scsi_cd, kref);
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struct gendisk *disk = cd->disk;
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spin_lock(&sr_index_lock);
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clear_bit(MINOR(disk_devt(disk)), sr_index_bits);
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spin_unlock(&sr_index_lock);
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unregister_cdrom(&cd->cdi);
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disk->private_data = NULL;
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put_disk(disk);
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mutex_destroy(&cd->lock);
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kfree(cd);
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}
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static int sr_remove(struct device *dev)
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{
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struct scsi_cd *cd = dev_get_drvdata(dev);
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@ -1046,11 +978,7 @@ static int sr_remove(struct device *dev)
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scsi_autopm_get_device(cd->device);
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del_gendisk(cd->disk);
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dev_set_drvdata(dev, NULL);
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mutex_lock(&sr_ref_mutex);
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kref_put(&cd->kref, sr_kref_release);
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mutex_unlock(&sr_ref_mutex);
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put_disk(cd->disk);
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return 0;
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}
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@ -18,7 +18,6 @@
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#ifndef _SR_H
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#define _SR_H
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#include <linux/kref.h>
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#include <linux/mutex.h>
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#define MAX_RETRIES 3
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@ -51,9 +50,6 @@ typedef struct scsi_cd {
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struct cdrom_device_info cdi;
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struct mutex lock;
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/* We hold gendisk and scsi_device references on probe and use
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* the refs on this kref to decide when to release them */
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struct kref kref;
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struct gendisk *disk;
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} Scsi_CD;
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