| Message ID | 1363687057-13580-2-git-send-email-gaowanlong@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2013-03-19 at 17:57 +0800, Wanlong Gao wrote: > From: Paolo Bonzini <pbonzini@redhat.com> > > virtio_scsi_target_state is now empty. We will find new uses for it in > the next few patches, so this patch does not drop it completely. > However, having dropped the sglist flexible array member, we can turn > the tgt array-of-pointers into a simple array. This simplifies the > allocation. > > Even simpler would be to place the virtio_scsi_target_state structs in a > flexible array member at the end of struct virtio_scsi. But we do not > do that, because we will place the virtqueues there in the next patches. I'm really sorry, but I must have been asleep at the wheel when I let code like this go in. No modern driver should have fixed arrays for target information. The way this is supposed to work is that you have entries in the host template for target_alloc and target_destroy. You hook into these and attach your struct virtio_scsi_target_state to scsi_target->hostdata, which you kmalloc in the target_alloc routine and kfree in the target_destroy routine. Now you get at it from the sdev with scsi_target(sdev)->hostdata. No messing around with fixed size arrays and bulk memory allocation and no need to pass in the maximum target size as a parameter because everything should now happen dynamically. Since you're redoing the code anyway, can you fix it to work this way? Thanks, James -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Il 19/03/2013 12:32, James Bottomley ha scritto: > On Tue, 2013-03-19 at 17:57 +0800, Wanlong Gao wrote: >> From: Paolo Bonzini <pbonzini@redhat.com> >> >> virtio_scsi_target_state is now empty. We will find new uses for it in >> the next few patches, so this patch does not drop it completely. >> However, having dropped the sglist flexible array member, we can turn >> the tgt array-of-pointers into a simple array. This simplifies the >> allocation. >> >> Even simpler would be to place the virtio_scsi_target_state structs in a >> flexible array member at the end of struct virtio_scsi. But we do not >> do that, because we will place the virtqueues there in the next patches. > > I'm really sorry, but I must have been asleep at the wheel when I let > code like this go in. No modern driver should have fixed arrays for > target information. The way this is supposed to work is that you have > entries in the host template for target_alloc and target_destroy. You > hook into these and attach your struct virtio_scsi_target_state to > scsi_target->hostdata, So that would be sc->device->sdev_target->hostdata. > which you kmalloc in the target_alloc routine and > kfree in the target_destroy routine. Now you get at it from the sdev > with scsi_target(sdev)->hostdata. No messing around with fixed size > arrays and bulk memory allocation and no need to pass in the maximum > target size as a parameter because everything should now happen > dynamically. The maximum target size is not a module parameter, it is given by the host; so the module itself is not placing arbitrary limitation. Still it is a good idea to do it like this. Thanks for the review. Paolo > Since you're redoing the code anyway, can you fix it to work this way? > > Thanks, > > James > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2013-03-19 at 12:45 +0100, Paolo Bonzini wrote: > Il 19/03/2013 12:32, James Bottomley ha scritto: > > On Tue, 2013-03-19 at 17:57 +0800, Wanlong Gao wrote: > >> From: Paolo Bonzini <pbonzini@redhat.com> > >> > >> virtio_scsi_target_state is now empty. We will find new uses for it in > >> the next few patches, so this patch does not drop it completely. > >> However, having dropped the sglist flexible array member, we can turn > >> the tgt array-of-pointers into a simple array. This simplifies the > >> allocation. > >> > >> Even simpler would be to place the virtio_scsi_target_state structs in a > >> flexible array member at the end of struct virtio_scsi. But we do not > >> do that, because we will place the virtqueues there in the next patches. > > > > I'm really sorry, but I must have been asleep at the wheel when I let > > code like this go in. No modern driver should have fixed arrays for > > target information. The way this is supposed to work is that you have > > entries in the host template for target_alloc and target_destroy. You > > hook into these and attach your struct virtio_scsi_target_state to > > scsi_target->hostdata, > > So that would be sc->device->sdev_target->hostdata. No, unfortunate name, but it's used for something else (actually, I think it *was* used by something else and is unused now). The construct is scsi_target(sc->device)->hostdata James -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index b53ba9e..3256c51 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -76,7 +76,7 @@ struct virtio_scsi { /* Get some buffers ready for event vq */ struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN]; - struct virtio_scsi_target_state *tgt[]; + struct virtio_scsi_target_state *tgt; }; static struct kmem_cache *virtscsi_cmd_cache; @@ -568,18 +568,9 @@ static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, virtscsi_vq->vq = vq; } -static struct virtio_scsi_target_state *virtscsi_alloc_tgt( - struct virtio_device *vdev) +static void virtscsi_init_tgt(struct virtio_scsi_target_state *tgt) { - struct virtio_scsi_target_state *tgt; - gfp_t gfp_mask = GFP_KERNEL; - - tgt = kmalloc(sizeof(*tgt), gfp_mask); - if (!tgt) - return NULL; - spin_lock_init(&tgt->tgt_lock); - return tgt; } static void virtscsi_scan(struct virtio_device *vdev) @@ -593,17 +584,10 @@ static void virtscsi_remove_vqs(struct virtio_device *vdev) { struct Scsi_Host *sh = virtio_scsi_host(vdev); struct virtio_scsi *vscsi = shost_priv(sh); - u32 i, num_targets; /* Stop all the virtqueues. */ vdev->config->reset(vdev); - - num_targets = sh->max_id; - for (i = 0; i < num_targets; i++) { - kfree(vscsi->tgt[i]); - vscsi->tgt[i] = NULL; - } - + kfree(vscsi->tgt); vdev->config->del_vqs(vdev); } @@ -640,13 +624,14 @@ static int virtscsi_init(struct virtio_device *vdev, if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) virtscsi_kick_event_all(vscsi); - for (i = 0; i < num_targets; i++) { - vscsi->tgt[i] = virtscsi_alloc_tgt(vdev); - if (!vscsi->tgt[i]) { - err = -ENOMEM; - goto out; - } + vscsi->tgt = kmalloc(num_targets * sizeof(vscsi->tgt[0]), GFP_KERNEL); + if (!vscsi->tgt) { + err = -ENOMEM; + goto out; } + for (i = 0; i < num_targets; i++) + virtscsi_init_tgt(&vscsi->tgt[i]); + err = 0; out: @@ -665,10 +650,7 @@ static int virtscsi_probe(struct virtio_device *vdev) /* Allocate memory and link the structs together. */ num_targets = virtscsi_config_get(vdev, max_target) + 1; - shost = scsi_host_alloc(&virtscsi_host_template, - sizeof(*vscsi) - + num_targets * sizeof(struct virtio_scsi_target_state)); - + shost = scsi_host_alloc(&virtscsi_host_template, sizeof(*vscsi)); if (!shost) return -ENOMEM;