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Re: [Qemu-devel] [PATCH v2 2/2] virtio-scsi: Optimize virtio_scsi_init_r
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH v2 2/2] virtio-scsi: Optimize virtio_scsi_init_req |
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Date: |
Mon, 15 Sep 2014 12:17:20 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 |
Il 15/09/2014 07:23, Fam Zheng ha scritto:
> SCSIRequest *sreq;
> size_t resp_size;
> enum SCSIXferMode mode;
> - QEMUIOVector resp_iov;
> union {
> VirtIOSCSICmdResp cmd;
> VirtIOSCSICtrlTMFResp tmf;
> @@ -68,23 +75,27 @@ static inline SCSIDevice
> *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
> static VirtIOSCSIReq *virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq)
> {
> VirtIOSCSIReq *req;
> - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
> -
> - req = g_malloc0(sizeof(*req) + vs->cdb_size);
> + VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
> + const size_t zero_skip = offsetof(VirtIOSCSIReq, elem)
> + + sizeof(VirtQueueElement);
>
> + req = g_slice_alloc(sizeof(*req) + vs->cdb_size);
Looks good, but why do you need to zero the union? You only need to
zero sreq, resp_size and mode, don't you (and at this point, memset
becomes superfluous)?
Paolo