Hi Hannes,
在 2021/11/25 23:10, Hannes Reinecke 写道:
Add a flag 'alloc_host_dev' to the SCSI host template and allocate
a virtual scsi device if the flag is set.
This device has the SCSI id <max_id + 1>:0, so won't clash with any
devices the HBA might allocate. It's also excluded from scanning and
will not show up in sysfs.
Intention is to use this device to send internal commands to the HBA.
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/scsi/hosts.c | 8 +++++
drivers/scsi/scsi_scan.c | 67 +++++++++++++++++++++++++++++++++++++-
drivers/scsi/scsi_sysfs.c | 3 +-
include/scsi/scsi_device.h | 2 +-
include/scsi/scsi_host.h | 21 ++++++++++++
5 files changed, 98 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index f69b77cbf538..a539fa2fb221 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -290,6 +290,14 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
if (error)
goto out_del_dev;
+ if (sht->alloc_host_sdev) {
+ shost->shost_sdev = scsi_get_host_dev(shost);
+ if (!shost->shost_sdev) {
+ error = -ENOMEM;
+ goto out_del_dev;
+ }
+ }
+
scsi_proc_host_add(shost);
scsi_autopm_put_host(shost);
return error;
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 328c0e79dfe7..e2910aa02a65 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1139,6 +1139,12 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
if (!sdev)
goto out;
+ if (scsi_device_is_host_dev(sdev)) {
+ if (bflagsp)
+ *bflagsp = BLIST_NOLUN;
+ return SCSI_SCAN_LUN_PRESENT;
+ }
+
result = kmalloc(result_len, GFP_KERNEL);
if (!result)
goto out_free_sdev;
@@ -1755,6 +1761,9 @@ static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
/* If device is already visible, skip adding it to sysfs */
if (sdev->is_visible)
continue;
+ /* Host devices should never be visible in sysfs */
+ if (scsi_device_is_host_dev(sdev))
+ continue;
if (!scsi_host_scan_allowed(shost) ||
scsi_sysfs_add_sdev(sdev) != 0)
__scsi_remove_device(sdev);
@@ -1919,12 +1928,16 @@ EXPORT_SYMBOL(scsi_scan_host);
void scsi_forget_host(struct Scsi_Host *shost)
{
- struct scsi_device *sdev;
+ struct scsi_device *sdev, *host_sdev = NULL;
unsigned long flags;
restart:
spin_lock_irqsave(shost->host_lock, flags);
list_for_each_entry(sdev, &shost->__devices, siblings) {
+ if (scsi_device_is_host_dev(sdev)) {
+ host_sdev = sdev;
+ continue;
+ }
if (sdev->sdev_state == SDEV_DEL)
continue;
spin_unlock_irqrestore(shost->host_lock, flags);
@@ -1932,5 +1945,57 @@ void scsi_forget_host(struct Scsi_Host *shost)
goto restart;
}
spin_unlock_irqrestore(shost->host_lock, flags);
+ /* Remove host device last, might be needed to send commands */
+ if (host_sdev)
+ __scsi_remove_device(host_sdev);
}
+/**
+ * scsi_get_host_dev - Create a virtual scsi_device to the host adapter
+ * @shost: Host that needs a scsi_device
+ *
+ * Lock status: None assumed.
+ *
+ * Returns: The scsi_device or NULL
+ *
+ * Notes:
+ * Attach a single scsi_device to the Scsi_Host. The primary aim
+ * for this device is to serve as a container from which valid
+ * scsi commands can be allocated from. Each scsi command will carry
+ * an unused/free command tag, which then can be used by the LLDD to
+ * send internal or passthrough commands without having to find a
+ * valid command tag internally.
+ */
+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->max_id);
+ if (!starget)
+ goto out;
+
+ sdev = scsi_alloc_sdev(starget, 0, NULL);
+ if (sdev)
+ sdev->borken = 0;
+ else
+ scsi_target_reap(starget);
Currently many scsi drivers fill some interfaces such as
target_alloc()/slave_alloc() for real disks.
When allocating scsi target and scsi device for host dev, it will also
call those interfaces, and not sure whether it breaks those drivers.
From function sas_target_alloc() (common interface in libsas layer), it
seems break it as there is no sas_rphy for host dev.
