On Tue, Apr 20, 2021 at 09:14:12AM +0100, John Garry wrote: > On 20/04/2021 01:02, Ming Lei wrote: > > On Tue, Apr 20, 2021 at 12:06:24AM +0800, John Garry wrote: > > > Function sdev_store_queue_depth() enforces that the sdev queue depth cannot > > > exceed shost.can_queue. > > > > > > However, the LLDD may still set cmd_per_lun > can_queue, which leads to an > > > initial sdev queue depth greater than can_queue. > > > > > > Stop this happened by capping initial sdev queue depth at can_queue. > > > > > > Signed-off-by: John Garry <john.garry@xxxxxxxxxx> > > > --- > > > Topic originally discussed at: > > > https://lore.kernel.org/linux-scsi/85dec8eb-8eab-c7d6-b0fb-5622747c5499@xxxxxxxxxxxx/T/#m5663d0cac657d843b93d0c9a2374f98fc04384b9 > > > > > > Last idea there was to error/warn in scsi_add_host() for cmd_per_lun > > > > > Hi Ming, > > > No, that isn't my suggestion. > > Right, it was what I mentioned. > > > > > > can_queue. However, such a shost driver could still configure the sdev > > > queue depth to be sound value at .slave_configure callback, so now thinking > > > the orig patch better. > > > > As I mentioned last time, why can't we fix ->cmd_per_lun in > > scsi_add_host() using .can_queue? > > > > I would rather not change the values which are provided from the driver. I > would rather take the original values and try to use them in a sane way. > > I have not seen other places where driver shost config values are modified > by the core code. Wrt. .cmd_per_lun, I think it is safe to modify it into one correct depth because almost all drivers are just producer of .cmd_per_lun. And except for debug purpose, there are only three consumers of .cmd_per_lun in scsi, and all are for scsi_change_queue_depth(): process_message() scsi_alloc_sdev() virtscsi_change_queue_depth() Thanks, Ming
