On 14/06/2022 20:33, Bart Van Assche wrote:
Hi Bart,
On 6/9/22 03:29, John Garry wrote:
+/**
+ * scsi_get_host_dev - Create a scsi_device that points to the host
adapter itself
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
What does this mean? That part of the function description is not
clear to me.
Agreed, this text is just as it was before (it was originally deleted)
but I can fix it up to make sense.
+ * @shost: Host that needs a scsi_device
^^^^^^^^^^^^^
This is not detailed enough. Consider changing "a scsi_device" into
"a scsi device for allocating reserved commands from".
+ *
+ * Lock status: None assumed.
+ *
+ * Returns: The scsi_device or NULL
+ *
+ * Notes:
+ * Attach a single scsi_device to the Scsi_Host - this should
+ * be made to look like a "pseudo-device" that points to the
+ * HA itself.
+ *
+ * Note - this device is not accessible from any high-level
+ * drivers (including generics), which is probably not
+ * optimal. We can add hooks later to attach.
The "which is probably not optimal. We can add hooks later to attach."
part probably should be moved to the patch description.
ok
+ */
+struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
+{
+ struct scsi_device *sdev = NULL;
+ struct scsi_target *starget;
+
+ mutex_lock(&shost->scan_mutex);
+ if (!scsi_host_scan_allowed(shost))
+ goto out;
+ starget = scsi_alloc_target(&shost->shost_gendev, 0,
shost->this_id);
^^^^^^^^^^^^^^^^^^
Is it guaranteed that this channel / id combination will not be used for
any other SCSI device?
Does it matter if the parent device is different?
What if shost->this_id == -1?
+ if (!starget)
+ goto out;
+
+ sdev = scsi_alloc_sdev(starget, 0, NULL);
+ if (sdev)
+ sdev->borken = 0;
+ else
+ scsi_target_reap(starget);
+ put_device(&starget->dev);
+ out:
+ mutex_unlock(&shost->scan_mutex);
+ return sdev;
+}
+EXPORT_SYMBOL(scsi_get_host_dev);
Elsewhere in the SCSI core "get..dev" means increment the reference
count of
a SCSI device. Maybe scsi_alloc_host_dev() is a better name?
I think that the intention is to only use this once for a shost, i.e.
get or allocate that scsi_device once and use it for the lifetime of the
shost. But I can rename if you think it's better.
+/*
+ * These two functions are used to allocate and free a pseudo device
+ * which will connect to the host adapter itself rather than any
+ * physical device. You must deallocate when you are done with the
+ * thing. This physical pseudo-device isn't real and won't be available
+ * from any high-level drivers.
+ */
Please keep function comments in .c files because that makes it more likely
that the comment and the implementation will remain in sync.
fine, I can relocate this.
Thanks,
John
