On 07/29/2014 04:57 PM, Juergen Gross wrote:
On 07/29/2014 03:53 PM, Christoph Hellwig wrote:
+ switch (op) {
+ case VSCSIFRONT_OP_ADD_LUN:
+ if (device_state == XenbusStateInitialised) {
+ sdev = scsi_device_lookup(info->host, chn, tgt,
+ lun);
+ if (sdev) {
+ dev_err(&dev->dev,
+ "Device already in use.\n");
+ scsi_device_put(sdev);
+ xenbus_printf(XBT_NIL, dev->nodename,
+ state_str, "%d",
+ XenbusStateClosed);
+ } else {
+ scsi_add_device(info->host, chn, tgt,
+ lun);
+ xenbus_printf(XBT_NIL, dev->nodename,
+ state_str, "%d",
+ XenbusStateConnected);
+ }
+ }
+ break;
scsi_add_device handles an already existing device just fine, and unlike
this construct isn't racy.
Okay. I'll change it.
Hmm, I looked into scsi_add_device(). It seems as if the caller can't
distinguish between a new created and an already existing device. Am I
missing something?
The race is not existing: scsi_add_device() (and scsi_remove_device()
as well) for this scsi_host is called in scsifront_do_lun_hotplug()
only, and this function is always called in the same thread (xenbus
watch). A comment seems to be a good idea.
Juergen
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