On 04/05/12 13:58, Tomas Henzl wrote: > When the async scan is protected this way a further protection via ref. count is no more needed > so remove it > diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c > index 29c4c04..be9e6fe 100644 > --- a/drivers/scsi/scsi_scan.c > +++ b/drivers/scsi/scsi_scan.c > @@ -1743,10 +1743,9 @@ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) > > data = kmalloc(sizeof(*data), GFP_KERNEL); > if (!data) > - goto err; > - data->shost = scsi_host_get(shost); > - if (!data->shost) > - goto err; > + return NULL; > + > + data->shost = shost; > init_completion(&data->prev_finished); > > mutex_lock(&shost->scan_mutex); Maybe it's better to leave the scsi_host_get() / scsi_host_put() pair in scsi_prep_async_scan() and scsi_finish_async_scan(). Let's have a look at the following code in scsi_finish_async_scan(): spin_lock_irqsave(shost->host_lock, flags); shost->async_scan = 0; spin_unlock_irqrestore(shost->host_lock, flags); If the context that is waiting for shost->async_scan wouldn't lock shost->host_lock after having observed that shost->async_scan became zero then shost->host_lock could already have been freed before scsi_finish_async_scan() has unlocked that spin lock. Personally I prefer to avoid having such subtle dependencies between the async scanning code and the context waiting for it to finish. Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
