[3.12,55/82] usb-storage: enable multi-LUN scanning when needed
diff mbox series

Message ID 20140220235021.135749141@linuxfoundation.org
State New, archived
Headers show
  • 3.12.13-stable review
Related show

Commit Message

Greg Kroah-Hartman Feb. 20, 2014, 11:52 p.m. UTC
3.12-stable review patch.  If anyone has any objections, please let me know.


From: Alan Stern <stern@rowland.harvard.edu>

commit 823d12c95c666fa7ab7dad208d735f6bc6afabdc upstream.

People sometimes create their own custom-configured kernels and forget
to enable CONFIG_SCSI_MULTI_LUN.  This causes problems when they plug
in a USB storage device (such as a card reader) with more than one

Fortunately, we can tell fairly easily when a storage device claims to
have more than one LUN.  When that happens, this patch asks the SCSI
layer to probe all the LUNs automatically, regardless of the config

The patch also updates the Kconfig help text for usb-storage,
explaining that CONFIG_SCSI_MULTI_LUN may be necessary.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Thomas Raschbacher <lordvan@lordvan.com>
CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
CC: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

 drivers/usb/storage/Kconfig    |    4 +++-
 drivers/usb/storage/scsiglue.c |    6 ++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

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diff mbox series

--- a/drivers/usb/storage/Kconfig
+++ b/drivers/usb/storage/Kconfig
@@ -18,7 +18,9 @@  config USB_STORAGE
 	  This option depends on 'SCSI' support being enabled, but you
 	  probably also need 'SCSI device support: SCSI disk support'
-	  (BLK_DEV_SD) for most USB storage devices.
+	  (BLK_DEV_SD) for most USB storage devices.  Some devices also
+	  will require 'Probe all LUNs on each SCSI device'
 	  To compile this driver as a module, choose M here: the
 	  module will be called usb-storage.
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -78,6 +78,8 @@  static const char* host_info(struct Scsi
 static int slave_alloc (struct scsi_device *sdev)
+	struct us_data *us = host_to_us(sdev->host);
 	 * Set the INQUIRY transfer length to 36.  We don't use any of
 	 * the extra data and many devices choke if asked for more or
@@ -102,6 +104,10 @@  static int slave_alloc (struct scsi_devi
 	blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
+	/* Tell the SCSI layer if we know there is more than one LUN */
+	if (us->protocol == USB_PR_BULK && us->max_lun > 0)
+		sdev->sdev_bflags |= BLIST_FORCELUN;
 	return 0;