PATCH: scsi-sd-last-sector-bug-flag.patch

PATCH: scsi-sd-last-sector-bug-flag.patch

[Hans de Goede]

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Hi all,

This patch adds a new scsi_device flag for devices which contain a bug where
the device crashes when the last sector is read in a larger then 1 sector read.

This is for example the case with sdcards in the HP PSC1350 printer cardreader
and in the HP PSC1610 printer cardreader.

Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>

Regards,

Hans

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This patch adds a new scsi_device flag for devices which contain a bug where
the device crashes when the last sector is read in a larger then 1 sector read.

This is for example the case with sdcards in the HP PSC1350 printer cardreader
and in the HP PSC1610 printer cardreader.

Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>
diff -up vanilla-2.6.24-rc7/include/scsi/scsi_device.h.psc1350 vanilla-2.6.24-rc7/include/scsi/scsi_device.h
--- vanilla-2.6.24-rc7/include/scsi/scsi_device.h.psc1350	2008-01-11 19:40:31.000000000 +0100
+++ vanilla-2.6.24-rc7/include/scsi/scsi_device.h	2008-01-11 19:40:48.000000000 +0100
@@ -142,6 +142,7 @@ struct scsi_device {
 	unsigned fix_capacity:1;	/* READ_CAPACITY is too high by 1 */
 	unsigned guess_capacity:1;	/* READ_CAPACITY might be too high by 1 */
 	unsigned retry_hwerror:1;	/* Retry HARDWARE_ERROR */
+	unsigned last_sector_bug:1;	/* Always read last sector in a 1 sector read */
 
 	DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
 	struct list_head event_list;	/* asserted events */
diff -up vanilla-2.6.24-rc7/drivers/scsi/sd.c.psc1350 vanilla-2.6.24-rc7/drivers/scsi/sd.c
--- vanilla-2.6.24-rc7/drivers/scsi/sd.c.psc1350	2008-01-11 19:55:43.000000000 +0100
+++ vanilla-2.6.24-rc7/drivers/scsi/sd.c	2008-01-20 10:49:17.000000000 +0100
@@ -395,6 +395,16 @@ static int sd_prep_fn(struct request_que
 		goto out;
 	}
 
+	/* 
+	 * Some devices (some sdcards for one) don't like it if the last sector
+	 * gets read in a larger then 1 sector read.
+	 */
+	if (unlikely(sdp->last_sector_bug && 
+	    rq->nr_sectors > sdp->sector_size / 512 &&
+ 	    block + this_count == get_capacity(disk))) {
+		this_count -= sdp->sector_size / 512;
+	}
+
 	SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt, "block=%llu\n",
 					(unsigned long long)block));
 

Re: PATCH: scsi-sd-last-sector-bug-flag.patch

[James Bottomley]

On Sun, 2008-01-20 at 11:12 +0100, Hans de Goede wrote:
> Hi all,
> 
> This patch adds a new scsi_device flag for devices which contain a bug where
> the device crashes when the last sector is read in a larger then 1 sector read.
> 
> This is for example the case with sdcards in the HP PSC1350 printer cardreader
> and in the HP PSC1610 printer cardreader.
> 
> Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>

This could have done with running through checkpatch.pl:

ERROR: trailing whitespace
#28: FILE: drivers/scsi/sd.c:398:
+^I/* $

ERROR: trailing whitespace
#32: FILE: drivers/scsi/sd.c:402:
+^Iif (unlikely(sdp->last_sector_bug && $

WARNING: braces {} are not necessary for single statement blocks
#32: FILE: drivers/scsi/sd.c:402:
+       if (unlikely(sdp->last_sector_bug && 
+           rq->nr_sectors > sdp->sector_size / 512 &&
+           block + this_count == get_capacity(disk))) {
+               this_count -= sdp->sector_size / 512;
+       }

ERROR: use tabs not spaces
#34: FILE: drivers/scsi/sd.c:404:
+ ^I    block + this_count == get_capacity(disk))) {$

WARNING: line over 80 characters
#49: FILE: include/scsi/scsi_device.h:142:
+       unsigned last_sector_bug:1;     /* Always read last sector in a
1 sector read */

total: 3 errors, 2 warnings, 23 lines checked

I've fixed all of these up.

James

Re: PATCH: scsi-sd-last-sector-bug-flag.patch

[Greg KH]

On Sun, Jan 20, 2008 at 11:12:26AM +0100, Hans de Goede wrote:
> Hi all,
>
> This patch adds a new scsi_device flag for devices which contain a bug 
> where
> the device crashes when the last sector is read in a larger then 1 sector 
> read.
>
> This is for example the case with sdcards in the HP PSC1350 printer 
> cardreader
> and in the HP PSC1610 printer cardreader.

Wait, we already handle this in the usb-storage driver, why are you
putting this in the scsi core now?

confused,

greg k-h

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Re: PATCH: scsi-sd-last-sector-bug-flag.patch

[Hans de Goede]

Greg KH wrote:
> On Sun, Jan 20, 2008 at 11:12:26AM +0100, Hans de Goede wrote:
>> Hi all,
>>
>> This patch adds a new scsi_device flag for devices which contain a bug 
>> where
>> the device crashes when the last sector is read in a larger then 1 sector 
>> read.
>>
>> This is for example the case with sdcards in the HP PSC1350 printer 
>> cardreader
>> and in the HP PSC1610 printer cardreader.
> 
> Wait, we already handle this in the usb-storage driver, why are you
> putting this in the scsi core now?
> 

No we don't, I've send patches for this to the usb-storage driver but they were 
refused as they modified scsi commands in flight, the consensus was that this 
should be done in the scsi layer, hence this patch.

> confused,

I've noticed, esp. with regards to your second mail to which I will reply next. 
There has been a lot of discussion about this ending in this (perfectly fine) 
patch, which is much better then my original hack if I may add that.

Regards,

Hans

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