Hi,
any news on this.
Matthieu CASTET
Le Tue, 22 Apr 2014 16:01:15 +0200,
Matthieu CASTET <matthieu.castet@xxxxxxxxxx> a écrit :
> Hi,
>
> while playing with suspend to ram I found a strange behavior with usb
> key.
>
> This can be easily reproduced by doing :
> - plug a usb key
> - start to read the usb key : "cat /dev/sdx > /dev/null"
> - go to suspend : "echo mem > /sys/power/state"
> - while in suspend, unplug and replug the usb key (simulate usb power
> loss for computer that keep power)
> - exit suspend
> - there is read error on the usb key
>
>
> Because the power was cut during s2ram, the usb stack reset the device
> <1>.
> When new data transfer are done, we got a UNIT_ATTENTION from the
> device <2> and IO error are returned to user space application.
>
> After some investigation it seems some (all on the 3 I tested) usb key
> report as removable, and scsi layer abort the transfer in case of
> UNIT_ATTENTION <3>.
>
> The usb storage driver call scsi_report_bus_reset after device reset,
> but because of commit dfcf7775 <4>, we don't ignore unit attention if
> "sshdr.asc == 0x28 && sshdr.ascq == 0x00" ("Not-ready to ready").
>
> If dfcf7775 is reverted there is no more Buffer I/O error.
>
> Is that possible to find a way to restore the behavior before dfcf7775
> commit (no Buffer I/O error after device reset) after a suspend to ram ?
>
>
> Matthieu CASTET
>
> PS : the same error happen if sg_reset -b /dev/sdx is used on the
> device.
>
>
> <1>
> [ 117.070255] usb 2-1.4: reset high-speed USB device number 3 using
> ehci-pci [...]
> [ 117.543922] Restarting tasks ... done.
> [ 117.548390] video LNXVIDEO:01: Restoring backlight state
> <2>
> [ 117.549179] sd 6:0:0:0: [sdb] Media Changed
> [ 117.549184] sd 6:0:0:0: [sdb]
> [ 117.549187] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
> [ 117.549189] sd 6:0:0:0: [sdb]
> [ 117.549191] Sense Key : Unit Attention [current]
> [ 117.549195] Info fld=0x0
> [ 117.549197] sd 6:0:0:0: [sdb]
> [ 117.549201] Add. Sense: Not ready to ready change, medium may have
> changed [ 117.549203] sd 6:0:0:0: [sdb] CDB:
> [ 117.549205] Read(10): 28 00 00 02 c9 00 00 00 f0 00
> [ 117.549212] end_request: I/O error, dev sdb, sector 182528
> [ 117.549218] Buffer I/O error on device sdb1, logical block 22560
> [ 117.549225] Buffer I/O error on device sdb1, logical block 22561
> [ 117.549228] Buffer I/O error on device sdb1, logical block 22562
> [ 117.549231] Buffer I/O error on device sdb1, logical block 22563
> [ 117.549233] Buffer I/O error on device sdb1, logical block 22564
> [ 117.549235] Buffer I/O error on device sdb1, logical block 22565
> [ 117.549238] Buffer I/O error on device sdb1, logical block 22566
> [ 117.549240] Buffer I/O error on device sdb1, logical block 22567
> [ 117.549243] Buffer I/O error on device sdb1, logical block 22568
> [ 117.549245] Buffer I/O error on device sdb1, logical block 22569
> [ 117.809462] sd 6:0:0:0: [sdb] No Caching mode page found
> [ 117.809470] sd 6:0:0:0: [sdb] Assuming drive cache: write through
> [ 117.812696] sd 6:0:0:0: [sdb] No Caching mode page found
> [ 117.812703] sd 6:0:0:0: [sdb] Assuming drive cache: write through
> [ 117.813688] sdb: sdb1
>
>
> <3>
> case UNIT_ATTENTION:
> if (cmd->device->removable) {
> /* Detected disc change. Set a bit
> * and quietly refuse further access.
> */
> cmd->device->changed = 1;
> description = "Media Changed";
> action = ACTION_FAIL;
> } else {
> /* Must have been a power glitch, or a
> * bus reset. Could not have been a
> * media change, so we just retry the
> * command and see what happens.
> */
> action = ACTION_RETRY;
> }
>
> <4>
> commit dfcf7775815504d13a1d273073810058caf84b9d
> Author: TARUISI Hiroaki <taruishi.hiroak@xxxxxxxxxxxxxx>
> Date: Thu Aug 11 20:25:20 2011 +0900
>
> [SCSI] Fix out of spec CD-ROM problem with media change
>
> Some CD-ROMs fail to report a media change correctly. The specific
> one for this patch simply fails to respond to commands, then gives a
> UNIT ATTENTION after being reset which returns ASC/ASCQ 28/00. This
> is out of spec behaviour, but add a check in the eat CC/UA on reset
> path to catch this case so the CD-ROM will function somewhat properly.
>
> [jejb: fixed up white space and accepted without signoff]
> Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
>
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index a4b9cdb..dc6131e 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -293,8 +293,16 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
> * so that we can deal with it there.
> */
> if (scmd->device->expecting_cc_ua) {
> - scmd->device->expecting_cc_ua = 0;
> - return NEEDS_RETRY;
> + /*
> + * Because some device does not queue unit
> + * attentions correctly, we carefully check
> + * additional sense code and qualifier so as
> + * not to squash media change unit attention.
> + */
> + if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
> + scmd->device->expecting_cc_ua = 0;
> + return NEEDS_RETRY;
> + }
> }
> /*
> * if the device is in the process of becoming ready, we
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