On Sun, 7 Mar 2010, Oliver Neukum wrote:
> Hi,
>
> any ideas?
>
> Mar 7 18:51:00 vanamonde kernel: usb-storage: Issuing auto-REQUEST_SENSE
> Mar 7 18:51:00 vanamonde kernel: usb-storage: Bulk Command S 0x43425355 T 0xff L 18 F 128 Trg 0 LUN 0 CL 6
> Mar 7 18:51:00 vanamonde kernel: usb-storage: usb_stor_bulk_transfer_buf: xfer 31 bytes
> Mar 7 18:51:00 vanamonde kernel: mon_text_get_data: num_sgs == 0: src ffff880037c07000
> Mar 7 18:51:00 vanamonde kernel: usb-storage: Status code 0; transferred 31/31
> Mar 7 18:51:00 vanamonde kernel: usb-storage: -- transfer complete
> Mar 7 18:51:00 vanamonde kernel: usb-storage: Bulk command transfer result=0
> Mar 7 18:51:00 vanamonde kernel: usb-storage: usb_stor_bulk_transfer_sglist: xfer 18 bytes, 1 entries
> Mar 7 18:51:00 vanamonde kernel: mon_text_get_data: num_sgs == 1: src ffff8801351ed440, length 18, scatterlist at ffff880134051dc8, page ffffea000439ebd8
>
> static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
> int len, char ev_type, struct mon_bus *mbus)
> {
> void *src;
>
> if (len <= 0)
> return 'L';
> if (len >= DATA_MAX)
> len = DATA_MAX;
>
> if (ep->is_in) {
> if (ev_type != 'C')
> return '<';
> } else {
> if (ev_type != 'S')
> return '>';
> }
>
> if (urb->num_sgs == 0) {
> src = urb->transfer_buffer;
> printk(KERN_ERR"%s: num_sgs == 0: src %p\n", __func__, src);
> if (src == NULL)
> return 'Z'; /* '0' would be not as pretty. */
> } else {
> struct scatterlist *sg = urb->sg->sg;
>
> /* If IOMMU coalescing occurred, we cannot trust sg_page */
> if (urb->sg->nents != urb->num_sgs ||
> PageHighMem(sg_page(sg)))
> return 'D';
>
> /* For the text interface we copy only the first sg buffer */
> len = min_t(int, sg->length, len);
> src = sg_virt(sg);
> printk(KERN_ERR"%s: num_sgs == %d: src %p, length %d, scatterlist at %p, page %p\n",
> __func__, urb->num_sgs, src, len, sg, sg_page(sg));
> }
>
> memcpy(ep->data, src, len);
> return 0;
> }
len and sg_page(sg) aren't particularly useful, as far as I can see.
sg and src need to be compared with the original values when the
scatterlist was created. In invoke_transport() print out the values of
scsi_sglist(srb), srb->sense_buffer, &ses->sense_sgl, and
sg_virt(&ses->sense_sgl). Do this after the call to
scsi_eh_prep_cmnd().
Alan Stern
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