On Sun, 20 Mar 2011, Richard Senior wrote:
> On 19/03/11 16:57, Alan Stern wrote:
>
> > The transcripts are not complete. Please run the tests again and post
> > the entire output from the dmesg command instead of just the tail of
> > the kernel log.
> >
> > Also, for the "bad" kernel you should enable CONFIG_USB_STORAGE_DEBUG.
>
> Please find transcripts/dmesg of fresh tests.
>
> The short transcripts show the commands I ran. I've included the tail of
> dmesg at appropriate points so that you can relate plugging/enabling to
> the complete dmesg output, which was captured at the end of the session.
Well done; this pinpoints the source of the problem. The patch below
should fix things up. Let me know how it works; if it is okay then
I'll submit it for inclusion in a 2.6.38.stable release.
Alan Stern
drivers/scsi/sd.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
Index: usb-2.6/drivers/scsi/sd.c
===================================================================
--- usb-2.6.orig/drivers/scsi/sd.c
+++ usb-2.6/drivers/scsi/sd.c
@@ -1904,17 +1904,23 @@ sd_read_cache_type(struct scsi_disk *sdk
int dbd;
int modepage;
+ int first_len;
struct scsi_mode_data data;
struct scsi_sense_hdr sshdr;
int old_wce = sdkp->WCE;
int old_rcd = sdkp->RCD;
int old_dpofua = sdkp->DPOFUA;
+ first_len = 4;
if (sdp->skip_ms_page_8) {
if (sdp->type == TYPE_RBC)
goto defaults;
else {
+ if (sdp->skip_ms_page_3f)
+ goto defaults;
modepage = 0x3F;
+ if (sdp->use_192_bytes_for_3f)
+ first_len = 192;
dbd = 0;
}
} else if (sdp->type == TYPE_RBC) {
@@ -1926,13 +1932,15 @@ sd_read_cache_type(struct scsi_disk *sdk
}
/* cautiously ask */
- res = sd_do_mode_sense(sdp, dbd, modepage, buffer, 4, &data, &sshdr);
+ res = sd_do_mode_sense(sdp, dbd, modepage, buffer, first_len,
+ &data, &sshdr);
if (!scsi_status_is_good(res))
goto bad_sense;
if (!data.header_length) {
modepage = 6;
+ first_len = 0;
sd_printk(KERN_ERR, sdkp, "Missing header in MODE_SENSE response\n");
}
@@ -1952,7 +1960,9 @@ sd_read_cache_type(struct scsi_disk *sdk
}
/* Get the data */
- res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len, &data, &sshdr);
+ if (len > first_len)
+ res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len,
+ &data, &sshdr);
if (scsi_status_is_good(res)) {
int offset = data.header_length + data.block_descriptor_length;
--
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