On Mon, 21 Feb 2011, Tanya Brokhman wrote:
> Hi All
>
> I was looking at the current implementation of do_mode_sense() in
> f_mass_storage.c (v2.6.38-rc5) and saw that there is no reference to the
> ALLOCATION LENGTH value from the CDB when issuing the reply.
Right.
> It seems to me that this might be an issue. For example the UAS host driver
> issues the following MODE SENSE CDB:
>
> 0x1a 0x00 0x3f 0x00 0x04 0x00
> Meaning:
> PC = 0x00 Current values
> Page Code = 0x3f all pages
> Allocation Length = 0x04
>
> According to the code in such case the MODE SENSE data reply length should
> be 16 bytes while the host expects to receive only 4 bytes.
Right.
> Shouldn't there be some sort of a length adjustment according to the
> Allocation Length value?
Indeed yes. Have you read the code in the middle and near the end of
do_scsi_cmnd()?
case MODE_SENSE:
common->data_size_from_cmnd = common->cmnd[4];
...
if (reply >= 0 && common->data_dir == DATA_DIR_TO_HOST) {
reply = min((u32)reply, common->data_size_from_cmnd);
bh->inreq->length = reply;
Alan Stern
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