| Message ID | 20220304160331.399757-5-hch@lst.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [01/14] blk-mq: do not include passthrough requests in I/O accounting | expand |
On 3/4/22 08:03, Christoph Hellwig wrote: > + /* > + * This device is mostly just used to show a bunch of attributes in a > + * weird place. In doubt don't add any new users, and most importantly > + * don't use if for any actual refcounting. > + */ > + struct device disk_dev; Isn't "weird place" subjective? How about mentioning the sysfs path explicitly (/sys/class/scsi_disk/H:C:I:L)? How about explaining why no new sysfs attributes should be added to that device instance? Thanks, Bart.
On Fri, Mar 04, 2022 at 05:03:21PM +0100, Christoph Hellwig wrote: > dev is very hard to grab for. Give the field a more descriptive name and > documents it's purpose. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > drivers/scsi/sd.c | 22 +++++++++++----------- > drivers/scsi/sd.h | 10 ++++++++-- > 2 files changed, 19 insertions(+), 13 deletions(-) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index 2a1e19e871d30..7479e7cb36b43 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -672,7 +672,7 @@ static struct scsi_disk *scsi_disk_get(struct gendisk *disk) > if (disk->private_data) { > sdkp = scsi_disk(disk); > if (scsi_device_get(sdkp->device) == 0) > - get_device(&sdkp->dev); > + get_device(&sdkp->disk_dev); > else > sdkp = NULL; > } > @@ -685,7 +685,7 @@ static void scsi_disk_put(struct scsi_disk *sdkp) > struct scsi_device *sdev = sdkp->device; > > mutex_lock(&sd_ref_mutex); > - put_device(&sdkp->dev); > + put_device(&sdkp->disk_dev); > scsi_device_put(sdev); > mutex_unlock(&sd_ref_mutex); > } > @@ -3529,14 +3529,14 @@ static int sd_probe(struct device *dev) > SD_MOD_TIMEOUT); > } > > - device_initialize(&sdkp->dev); > - sdkp->dev.parent = get_device(dev); > - sdkp->dev.class = &sd_disk_class; > - dev_set_name(&sdkp->dev, "%s", dev_name(dev)); > + device_initialize(&sdkp->disk_dev); > + sdkp->disk_dev.parent = get_device(dev); > + sdkp->disk_dev.class = &sd_disk_class; > + dev_set_name(&sdkp->disk_dev, "%s", dev_name(dev)); > > - error = device_add(&sdkp->dev); > + error = device_add(&sdkp->disk_dev); > if (error) { > - put_device(&sdkp->dev); > + put_device(&sdkp->disk_dev); > goto out; > } > > @@ -3577,7 +3577,7 @@ static int sd_probe(struct device *dev) > > error = device_add_disk(dev, gd, NULL); > if (error) { > - put_device(&sdkp->dev); > + put_device(&sdkp->disk_dev); > goto out; > } > > @@ -3628,7 +3628,7 @@ static int sd_remove(struct device *dev) > sdkp = dev_get_drvdata(dev); > scsi_autopm_get_device(sdkp->device); > > - device_del(&sdkp->dev); > + device_del(&sdkp->disk_dev); > del_gendisk(sdkp->disk); > sd_shutdown(dev); > > @@ -3636,7 +3636,7 @@ static int sd_remove(struct device *dev) > > mutex_lock(&sd_ref_mutex); > dev_set_drvdata(dev, NULL); > - put_device(&sdkp->dev); > + put_device(&sdkp->disk_dev); > mutex_unlock(&sd_ref_mutex); > > return 0; > diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h > index 303aa1c23aefb..7625a90b0fa69 100644 > --- a/drivers/scsi/sd.h > +++ b/drivers/scsi/sd.h > @@ -69,7 +69,13 @@ enum { > > struct scsi_disk { > struct scsi_device *device; > - struct device dev; > + > + /* > + * This device is mostly just used to show a bunch of attributes in a > + * weird place. In doubt don't add any new users, and most importantly > + * don't use if for any actual refcounting. > + */ The device looks partner of gendisk, I think it could just be a private data of gendisk, and the attributes can be added to gendisk. But scsi has the tradition of adding class device of scsi_host, scsi_device, scsi_disk and scsi_generic. Adding such device makes things complicated, such as refcounting in open/close disk. But looks scsi_disk isn't part of sysfs ABI, maybe it can be removed, anyway: Reviewed-by: Ming Lei <ming.lei@redhat.com> Thanks, Ming
On Sat, Mar 05, 2022 at 05:38:40PM -0800, Bart Van Assche wrote: > On 3/4/22 08:03, Christoph Hellwig wrote: >> + /* >> + * This device is mostly just used to show a bunch of attributes in a >> + * weird place. In doubt don't add any new users, and most importantly >> + * don't use if for any actual refcounting. >> + */ >> + struct device disk_dev; > > Isn't "weird place" subjective? How about mentioning the sysfs path > explicitly (/sys/class/scsi_disk/H:C:I:L)? How about explaining why no new > sysfs attributes should be added to that device instance? Well, weird place means that all normale drivers would just use attributes on the gendisk for it, but sd creates a completely pointless device under the gendisk device for it. If you have a better wording I can change it.
On Sun, Mar 06, 2022 at 11:31:33AM +0800, Ming Lei wrote: > The device looks partner of gendisk, I think it could just be a > private data of gendisk, and the attributes can be added to gendisk. Yes, that would be the normal way to do it. > > But scsi has the tradition of adding class device of scsi_host, > scsi_device, scsi_disk and scsi_generic. > > Adding such device makes things complicated, such as refcounting > in open/close disk. But looks scsi_disk isn't part of sysfs ABI, maybe it > can be removed, anyway: Unfortunatly it is in a major way: root@testvm:~# ls /sys/class/scsi_disk/0\:0\:0\:0 FUA manage_start_stop protection_mode uevent allow_restart max_medium_access_timeouts protection_type zeroing_mode app_tag_own max_retries provisioning_mode zoned_cap cache_type max_write_same_blocks subsystem device power thin_provisioning
On 3/6/22 00:40, Christoph Hellwig wrote: > On Sat, Mar 05, 2022 at 05:38:40PM -0800, Bart Van Assche wrote: >> On 3/4/22 08:03, Christoph Hellwig wrote: >>> + /* >>> + * This device is mostly just used to show a bunch of attributes in a >>> + * weird place. In doubt don't add any new users, and most importantly >>> + * don't use if for any actual refcounting. >>> + */ >>> + struct device disk_dev; >> >> Isn't "weird place" subjective? How about mentioning the sysfs path >> explicitly (/sys/class/scsi_disk/H:C:I:L)? How about explaining why no new >> sysfs attributes should be added to that device instance? > > Well, weird place means that all normale drivers would just use > attributes on the gendisk for it, but sd creates a completely pointless > device under the gendisk device for it. If you have a better wording > I can change it. It's not that important. I wish it would be possible to get rid of this struct device instance. I think this instance was introduced in 2006 by patch "[SCSI] allow displaying and setting of cache type via sysfs". Reviewed-by: Bart Van Assche <bvanassche@acm.org>
On 3/4/22 08:03, Christoph Hellwig wrote: > dev is very hard to grab for. Give the field a more descriptive name and > documents it's purpose. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- Looks good. Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Christoph, > dev is very hard to grab for. grep? > Give the field a more descriptive name and documents it's purpose. its > + > + /* > + * This device is mostly just used to show a bunch of attributes in a > + * weird place. In doubt don't add any new users, and most importantly > + * don't use if for any actual refcounting. > + */ > + struct device disk_dev; I agree with Bart that this should be more explicit about the /sys/class/scsi_disk location. Otherwise it is not clear which device the comment refers to. Otherwise OK. Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 2a1e19e871d30..7479e7cb36b43 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -672,7 +672,7 @@ static struct scsi_disk *scsi_disk_get(struct gendisk *disk) if (disk->private_data) { sdkp = scsi_disk(disk); if (scsi_device_get(sdkp->device) == 0) - get_device(&sdkp->dev); + get_device(&sdkp->disk_dev); else sdkp = NULL; } @@ -685,7 +685,7 @@ static void scsi_disk_put(struct scsi_disk *sdkp) struct scsi_device *sdev = sdkp->device; mutex_lock(&sd_ref_mutex); - put_device(&sdkp->dev); + put_device(&sdkp->disk_dev); scsi_device_put(sdev); mutex_unlock(&sd_ref_mutex); } @@ -3529,14 +3529,14 @@ static int sd_probe(struct device *dev) SD_MOD_TIMEOUT); } - device_initialize(&sdkp->dev); - sdkp->dev.parent = get_device(dev); - sdkp->dev.class = &sd_disk_class; - dev_set_name(&sdkp->dev, "%s", dev_name(dev)); + device_initialize(&sdkp->disk_dev); + sdkp->disk_dev.parent = get_device(dev); + sdkp->disk_dev.class = &sd_disk_class; + dev_set_name(&sdkp->disk_dev, "%s", dev_name(dev)); - error = device_add(&sdkp->dev); + error = device_add(&sdkp->disk_dev); if (error) { - put_device(&sdkp->dev); + put_device(&sdkp->disk_dev); goto out; } @@ -3577,7 +3577,7 @@ static int sd_probe(struct device *dev) error = device_add_disk(dev, gd, NULL); if (error) { - put_device(&sdkp->dev); + put_device(&sdkp->disk_dev); goto out; } @@ -3628,7 +3628,7 @@ static int sd_remove(struct device *dev) sdkp = dev_get_drvdata(dev); scsi_autopm_get_device(sdkp->device); - device_del(&sdkp->dev); + device_del(&sdkp->disk_dev); del_gendisk(sdkp->disk); sd_shutdown(dev); @@ -3636,7 +3636,7 @@ static int sd_remove(struct device *dev) mutex_lock(&sd_ref_mutex); dev_set_drvdata(dev, NULL); - put_device(&sdkp->dev); + put_device(&sdkp->disk_dev); mutex_unlock(&sd_ref_mutex); return 0; diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h index 303aa1c23aefb..7625a90b0fa69 100644 --- a/drivers/scsi/sd.h +++ b/drivers/scsi/sd.h @@ -69,7 +69,13 @@ enum { struct scsi_disk { struct scsi_device *device; - struct device dev; + + /* + * This device is mostly just used to show a bunch of attributes in a + * weird place. In doubt don't add any new users, and most importantly + * don't use if for any actual refcounting. + */ + struct device disk_dev; struct gendisk *disk; struct opal_dev *opal_dev; #ifdef CONFIG_BLK_DEV_ZONED @@ -126,7 +132,7 @@ struct scsi_disk { unsigned security : 1; unsigned ignore_medium_access_errors : 1; }; -#define to_scsi_disk(obj) container_of(obj,struct scsi_disk,dev) +#define to_scsi_disk(obj) container_of(obj, struct scsi_disk, disk_dev) static inline struct scsi_disk *scsi_disk(struct gendisk *disk) {
dev is very hard to grab for. Give the field a more descriptive name and documents it's purpose. Signed-off-by: Christoph Hellwig <hch@lst.de> --- drivers/scsi/sd.c | 22 +++++++++++----------- drivers/scsi/sd.h | 10 ++++++++-- 2 files changed, 19 insertions(+), 13 deletions(-)