On Thu, 8 Sep 2005, Jim Ramsay wrote: > More information: > > The error only occurrs during device sensing when the > srb->request_buffer is assigned as follows, by usb/storage/transport.c > in the routine usb_stor_invoke_transport: > > old_request_buffer = srb->request_buffer; > srb->request_buffer = srb->sense_buffer; > > Now, this is a problem because srb->sense_buffer is defined as follows > in the struct scsi_cmnd: > > #define SCSI_SENSE_BUFFERSIZE 96 > unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE]; > > Since it is not allocated at runtime there is NO WAY the SCSI layer > can possibly guarantee it is page- or cache-aligned and ready for DMA. > > Any suggestions on best fix for this? Is it still a SCSI-layer issue? > Or should USB step up in this case and ensure this buffer is dma-safe > itself? Aha! I've long thought that usb-storage should allocate its own transfer buffer for sense data. In the past people have said, "No, don't bother, it's not really needed." Here's a good reason for doing it. Expect a patch before long. Alan Stern - : 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
