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| author | Alan Stern <stern@rowland.harvard.edu> | 2008-07-29 11:58:06 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-08-13 17:32:50 -0700 |
| commit | 59f4ff2ecff4cef36378928cec891785b402e80c (patch) | |
| tree | b49428f1fd19f26c75ed3e2d6994ba72d3a3d190 /drivers/usb/storage | |
| parent | 1a21175a615ed346e8043f5e9d60a672266b84b4 (diff) | |
| download | lwn-59f4ff2ecff4cef36378928cec891785b402e80c.tar.gz lwn-59f4ff2ecff4cef36378928cec891785b402e80c.zip | |
usb-storage: automatically recognize bad residues
This patch (as1119) will help to reduce the clutter of usb-storage's
unusual_devs file by automatically detecting some devices that need
the IGNORE_RESIDUE flag. The idea is that devices should never return
a non-zero residue for an INQUIRY or a READ CAPACITY command unless
they failed to transfer all the requested data. So if one of these
commands transfers a standard amount of data but there is a positive
residue, we know that the residue is bogus and we can set the flag.
This fixes the problems reported in Bugzilla #11125.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/storage')
| -rw-r--r-- | drivers/usb/storage/transport.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c index fcbbfdb7b2b0..3523a0bfa0ff 100644 --- a/drivers/usb/storage/transport.c +++ b/drivers/usb/storage/transport.c @@ -1032,8 +1032,21 @@ int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us) /* try to compute the actual residue, based on how much data * was really transferred and what the device tells us */ - if (residue) { - if (!(us->fflags & US_FL_IGNORE_RESIDUE)) { + if (residue && !(us->fflags & US_FL_IGNORE_RESIDUE)) { + + /* Heuristically detect devices that generate bogus residues + * by seeing what happens with INQUIRY and READ CAPACITY + * commands. + */ + if (bcs->Status == US_BULK_STAT_OK && + scsi_get_resid(srb) == 0 && + ((srb->cmnd[0] == INQUIRY && + transfer_length == 36) || + (srb->cmnd[0] == READ_CAPACITY && + transfer_length == 8))) { + us->fflags |= US_FL_IGNORE_RESIDUE; + + } else { residue = min(residue, transfer_length); scsi_set_resid(srb, max(scsi_get_resid(srb), (int) residue)); |